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This paper presents an investigation conducted in a public university in central Mexico into the possible influence of learners’ perceptions of task difficulty (TD) on levels of complexity, accuracy and fluency (CAF) during the performance of three tasks (personal information, narrative and decision-making tasks). Firstly, four learner pairs performed the three tasks, and their levels of CAF were measured. Secondly, the participants were interviewed retrospectively about which tasks they perceived as difficult and their reasons for such perceived difficulty. In combining the quantitative and qualitative analyses, the data reveal that task difficulty increases when a task is perceived not to be familiar by the learner. The relationship between task difficulty and familiarity also appears to influence the levels of CAF, promoting high levels of fluency and accuracy when the task is perceived by the learner as easy and familiar. The findings of this study provide support for a cognitive approach to task-based language learning and put forward the need to include learners’ perceptions of TD as a variable to investigate the relationship between tasks and the CAF dimensions., Este artículo presenta una investigación llevada a cabo en una universidad pública en el centro de México sobre la posible influencia de las percepciones de los estudiantes sobre la dificultad de las tareas en la complejidad, precisión y fluidez (CPF) durante el desarrollo de tres tareas (tareas de información personal, narrativas y de negociación). En primer lugar, cuatro parejas de estudiantes realizaron las tres tareas y sus niveles de CPF fueron medidos. En segundo lugar, se realizaron entrevistas retrospectivas para examinar qué tareas fueron percibidas como difíciles y los factores que influyeron sobre estas percepciones. Al combinar datos cuantitativos y cualitativos, los resultados muestran que la dificultad de las tareas se incrementa cuando la tarea no es familiar para los estudiantes. La relación entre la dificultad de las tareas y la familiaridad también influye en los niveles de CPF, promoviendo niveles altos de fluidez y precisión cuando la tarea es percibida como fácil y familiar. Los resultados de este estudio apoyan el enfoque cognitivo para el aprendizaje basado en tareas y muestran la necesidad de incluir las percepciones de los estudiantes sobre la dificultad de las tareas como una variable para investigar la relación entre las tareas y las dimensiones de CPF.

This paper focuses on the analysis of Bebras Challenge tasks to find Informatics tasks that develop abstract thinking. Our study seeks to find which Bebras tasks develop abstraction and in what way. We analysed hundreds of tasks from the Czech contest to identify those tasks requiring participants to abstract directly or use abstract structures. Results show that an agreement among experts on stating which task is focused on abstraction is at a moderate level. We discovered that tasks focused on abstraction occur four to five times less frequently in sets of contest tasks than algorithmic tasks. Our findings proved that abstract tasks results compared with algorithmic ones did not differ in neither age nor gender group of contestants.

This is a preregistration of additional data collection. To test our hypotheses, we have collected the data for the three task difficulty levels, i.e. 1-back, 2-back, and 3-back. 274 individuals participated in the study (139 women and 135 men). However, the results were inconclusive. Therefore, we intend to collect additional data for an extra difficulty level - 5-back, which, as we expect, will clarify the results.

This study sets out to investigate how the magnitude of task difficulty affects challenge and hindrance appraisals and performance in a laboratory setting.

It is common to see university students studying within coffee-shops (Byung-yeul & Ji-youn, 2014). Some students may also use fans when studying; the low-hum of the fan, similar to white-noise, can help to drown out other noises or provide additional auditory stimulation when it feels too quiet (Sabine, n.d.). Lleras and collogues (2013) found that in environments where participants need to spend more executive resources to perform a task well, they will spontaneously withdraw their attentiveness from irrelevant tasks (Lleras et al., 2013). Advancing this line of research, Ralph and colleagues (2018) examined whether people modulate their level of media multitasking as a function of primary task difficulty and found most participants chose to keep a distracting video playing when performing an easy task but significantly attenuated the video during a difficult task. These results suggest that as the difficulty of people’s primary task increases, they are more likely to withdraw their receptors from task-irrelevant distractors. Modulation in response to task difficulty is relatively novel question in the attention literature, and the proposed study expands upon this past research , similarly allowing participants to modulate external ambient sounds, but also differentiated via the novel use of audial distractors in contrast to visual stimuli. The primary aim of the present study is to assess whether people will modulate the volume of background noise depending on the difficulty of the primary task (n-back) , and to what degree this modulation depends on the type of ambient noise. The second aim is to clarify how ambience will influence subjective (mind-wandering) and objective measures of attentional engagement. To address these aims, we will manipulate the difficulty of a primary task within participants and the nature of the background noise between participants. As we aim to replicate environments that participants may be familiar with, we will use sounds collected from coffee shops and fans running.

Although response to a stressor is a dynamic unfolding process, that can be captured through changes in cognitive appraisals of the stressor (Lazarus & Folkman, 1984), the overwhelming majority of organizational research treats it as a static event. This project addresses the relatively unexplored temporal aspects of the work stressor-performance relationship with the focus on the challenge and hindrance appraisals and attentional processes by conducting two studies. Specifically, we aim to examine how task performance (operationalized as concurrent performance feedback, i.e., the simultaneous display of objective feedback and upward social comparison feedback) is related to changes in challenge and hindrance appraisals and attention in a low and high difficulty cognitive task. Given that in an organizational settings individuals typically have access to both objective performance information as well as social comparison performance information simultaneously (i.e., concurrent feedback) (Klein, 2003; Zhao, 2021), and that social comparisons can have stress-relieving and/or stress-inducing effects (Greenberg et al., 2007; Mendes, Blascovich, Major, & Seery, 2001), it is relevant to explore how concurrent feedback is associated with challenge and hindrance appraisals. We investigate this topic by conducting two studies. In Study 1, we will explore how task performance (operationalized as concurrent performance feedback) is related to changes in challenge and hindrance appraisals. In Study 2, we will examine the role of attentional focus on the two elements of concurrent feedback (i.e. objective feedback and upward social comparison feedback) in these relationships with the eye-tracking technology. We will employ between-subject 2x1(task difficulty: low vs. high) x (concurrent feedback) design. The experimental paradigm employed in this study will be the n-back task (see more details under the “Condition” section of this pre-registration.

Two folders ('data' and 'scripts') contain data and scripts used for online and offline response time measurements in Chetverikov, Upravitelev (2015) Online versus offline: The Web as a medium for response time data collection.

Cognitive effort is intrinsically linked to task difficulty, intelligence, and mental toughness. Intelligence reflects an individual’s cognitive aptitude, whereas mental toughness (MT) reflects an individual’s resilience in pursuing success. Research shows that parietal alpha oscillations are associated with changes in task difficulty. Critically, it remains unclear whether parietal alpha oscillations are modulated by intelligence and MT as a personality trait. We examined event-related (de)synchronization (ERD/ERS) of alpha oscillations associated with encoding, retention, and recognition in the Sternberg task in relation to intelligence and mental toughness. Eighty participants completed the Sternberg task with 3, 4, 5 and 6 digits, Raven Standard Progressive Matrices test and an MT questionnaire. A positive dependence on difficulty was observed for all studied oscillatory effects (t = −8.497, p < 0.001; t = 2.806, p < 0.005; t = −2.103, p < 0.05). The influence of Raven intelligence was observed for encoding-related alpha ERD (t = −2.02, p = 0.049). The influence of MT was observed only for difficult conditions in recognition-related alpha ERD (t = −3.282, p < 0.005). Findings indicate that the modulation of alpha rhythm related to encoding, retention and recognition may be interpreted as correlates of cognitive effort modulation. Specifically, results suggest that effort related to encoding depends on intelligence, whereas recognition-related effort level depends on mental toughness.

Previous studies have demonstrated that cognitive load (Luna, Barttfeld et al., 2022) and perceptual difficulty (Ortiz et al., 2021) when independently manipulated modulate the executive vigilance decrement as measured with the ANTI-Vea. The present study aims at investigating how the combination of different levels of cognitive load (single, dual, and triple task) and perceptual difficulty (easy/medium/hard) modulate the vigilance decrement in a repeated-measures design study. We expect the present study would contribute to the vigilance literature by testing the predictions of some of the traditional and alternative theories of the vigilance decrement phenomenon (i.e., resources depletion, mind-wandering, and resources control).

The suitability of touchscreens for human–computer interaction in manned/unmanned aerial vehicle cooperative missions remains uncertain, especially in situations that are time-sensitive with variations in difficulty levels. The purpose of this study is to determine the feasibility of touchscreen applications in manned/unmanned aerial vehicle cooperative missions and the magnitude of the effects of time pressure and task difficulty. In contrast to previous studies, a combination of performance and perceptual load measures was used to divide errors into disposition errors, undetected errors, and miscalculation errors to explore specific error mechanisms, set up typical manned/unmanned aerial vehicle cooperative human–computer interaction tasks, and set up antecedent features for potential factors. Thirty subjects participated in an experiment that required the use of touchscreens or keyboards to perform a human–computer interaction task in a simulated manned/unmanned aerial vehicle cooperative mission. Experiments were set at three task difficulties: low, medium, and high, and were matched to a set time pressure or no time pressure for two seconds for low difficulty, three seconds for medium difficulty, and four seconds for high difficulty. The results showed that the touchscreens improved the participants’ response speed at a time pressure of 2 s or less compared with the use of a general input device; however, the task error rate also increased significantly. The higher the task difficulty was, the worse the performance was and the greater the perceived workload of the participants. The application of touchscreens in dynamic environments subjected the participants to greater physical demands. The performance of participants using a keyboard was no better than that when touchscreens were used during the experiment. Moreover, touchscreens did not significantly improve participant performance. The results support the possibility of using touchscreens in manned/unmanned aerial vehicle cooperative missions.

This paper draws on affective load theory to explore the characteristics of users' affective load in collaborative searching. In this experimental study, a total of 32 participants were recruited and divided into 16 pair-groups. Each pair-group collaboratively completed three search tasks in the Coagmento system. Users reported more irritation than anxiety, frustration, and rage. Moreover, the greater a task's perceived difficulty, the higher the irritation, anxiety and frustration felt by users. Users' affective load was higher when they spent more time on a search than they expected to. Conversely, their sense of retrieval success, self-motivation to search contributed to reducing users' perceived affective load, but not as much as satisfaction with collaborative search results, and satisfaction with collaborative task outcomes did. Refereed/Peer-reviewed

Although a general age-related decline in neural plasticity is evident, the effects of age on neural plasticity after motor practice are inconclusive. Inconsistencies in the literature may be related to between-study differences in task difficulty. Therefore, we aimed to determine the effects of age and task difficulty on motor learning and associated brain activity. We used task-related electroencephalography (EEG) power in the alpha (8–12 Hz) and beta (13–30 Hz) frequency bands to assess neural plasticity before, immediately after, and 24-h after practice of a mirror star tracing task at one of three difficulty levels in healthy younger (19–24 yr) and older (65–86 yr) adults. Results showed an age-related deterioration in motor performance that was more pronounced with increasing task difficulty and was accompanied by a more bilateral activity pattern for older vs. younger adults. Task difficulty affected motor skill retention and neural plasticity specifically in older adults. Older adults that practiced at the low or medium, but not the high, difficulty levels were able to maintain improvements in accuracy at retention and showed modulation of alpha TR-Power after practice. Together, these data indicate that both age and task difficulty affect motor learning, as well as the associated neural plasticity.

Modern consumers face a dramatic rise in web-based technological advancements and have trouble making rational and proper decisions when they shop online. When they try to make decisions about products and services, they also feel pressured against time when sorting among all of the unnecessary items in the flood of information available on the web. In this sense, they need to use consumer decision-making creativity (CDMC) to make rational decisions. However, unexplored research questions on this subject remain. First, in what ways do task difficulty and time constraints affect visual attention on exploitative and exploratory activities differently? Second, how does the location of the reference (i.e., hints) influence the level of visual attention to exploitative and exploratory activities depending on affordance theory? Third, how do exploratory and exploitative activities affect CDMC? Eye-tracking experiments were conducted with 70 participants to obtain relevant metrics such as total fixation duration (TFD), fixation count (FC), and visit count (VC) to answer these research questions. Our findings suggest that task difficulty influences exploitative activity, whereas time constraint is related to the exploratory activity. The result of the location of hints aligns with the affordance theory for the exploitative activity. Besides, exploratory activity positively affected CDMC, but exploitative activity did not show any effect.

The auditory pathway consists of multiple recurrent loops of afferent and efferent connections that extend from the cochlea up to the prefrontal cortex. The early‐filter theory proposes that these loops allow top‐down filtering of early and middle latency auditory responses. Furthermore, the adaptive filtering model suggests that the filtering of irrelevant auditory stimuli should start lower in the pathway during more demanding tasks. If so, the 40‐Hz auditory steady‐state responses (ASSRs) to irrelevant sounds should be affected by top‐down crossmodal attention to a visual task, and effects should vary with the load of the visual task. Because few studies have examined this possibility, we conducted two preregistered studies that manipulated visual load (Study 1: N = 43, Study 2: N = 45). Study 1 used two levels (low and high), and Study 2 used four levels (no, low, high, and very high). Subjects were asked to ignore a 500‐Hz task‐irrelevant tone that was amplitude‐modulated to evoke 40‐Hz ASSRs. Results from Bayesian analyses provided moderate to extreme support for no effect of load (or of a task) on ASSRs. Results also supported no interaction with time (i.e., over blocks, over minutes, or with changes in ASSRs that were synchronized with the onset of the visual stimuli). Further, results provided moderate support for no correlation between the effects of load and working memory capacity. Because the present findings support the robustness of ASSRs against manipulations of crossmodal attention, they are not consistent with the adaptive filtering model., The adaptive filtering model suggests that the filtering of irrelevant auditory stimuli should start lower in the auditory pathway during more demanding tasks. Two preregistered studies (N = 43, N = 45) examined the effects of visual perceptual load (from no to very high) on the 40‐Hz auditory steady‐state response (ASSR) to a task‐irrelevant tone. Bayesian analyses provided evidence for no effect of load. This robustness of ASSR against manipulations of crossmodal attention is not consistent with the adaptive filter model.

El diseño de tareas es un tema crucial dentro del análisis didáctico de las matemáticas en educación secundaria. Dentro de este diseño un papel importante lo toma ladificultad de estas tareas. Lograr adaptar una tarea a un nivel lo suficientemente desafiante como para que los alumnos avancen en su conocimiento de la materia a la vez que son lo suficientemente asequibles como para que no se frustren en su realización y abandonen. Esto requiere de un análisis profundo por parte del profesor tanto de su clase como del contexto que la rodea. Se indaga en el diseño de tareas y dentro de él en las diferentes maneras de clasificar la dificultad de una tarea, cómo esta se define en la literatura educativa matemática general con el objetivo de preparar tareas que permitan el desarrollo adecuada de los alumnos. Para justificar este interés por la complejidad de las tareas se expone de manera general varias teorías de lamotivación en el alumnado, dónde la dificultad que posean las tareas es un factor fundamental para que nuestros alumnos tengan un desarrollo adecuado de la asignatura y despierte su interés por las matemáticas, en lugar de perpetuar una opinión generalque coloca a las matemáticas como una asignatura muy complicada. Todo esto se aplica en el diseño de tareas específicas para un curso de 1º ESO con los contenidos de ecuaciones de primer grado. Este tema es especialmente interesante por implicar en el alumnado el paso de una mentalidad aritmética a una nueva mentalidad algebraica. Provocando dificultades de comprensión que han sido investigadas. También se describen varios estudios centrados en el tema. Abstract: Task design is a crucial topic within the didactic analysis of mathematics in secondary school. Within this design, an important role is taken by the difficulty of these tasks, adapting a task to a level that is challenging enough for students to advance their knowledge of the subject while being affordable enough so that students don’t fall in frustration in their accomplishment. This requires a deep analysis by the teacher of both his class and the context that surrounds it. The design of tasks is investigated and within it in the different ways of classifying the difficulty of a task, how it is defined in the general mathematical educational literature with the aim of preparing tasks that allow the adequate development of the students. To justify this interest in the complexity of the tasks, several theories of motivation in students are generally exposed, where thedifficulty of the tasks is a fundamental factor for our students to have an adequate development of the subject and arouse their interest on maths, instead of perpetuating a general opinion that places mathematics as a very complicated subject. All this is applied in the design of specific tasks for a 1st ESO course with the contents of first grade equations. This topic is especially interesting for involving students in the transition from an arithmeticmindset to a new algebraic mindset. Provoking comprehension difficulties that have been investigated. Several studies focusing on the topic are also described.

Construct specification equations (CSEs), providing a comprehensive understanding of the construct purported to be measured and how a collection of items works together causally, are candidate ‘recipes for certified reference materials’ (CRM). Analogous to the role of CRMs in areas such as chemistry and material properties, CSEs appear to provide metrological traceability in the human sciences. In this work we illustrate how memory test items, Rasch Measurement Theory (RMT) and CSEs can be brought together to help ‘tell a clearer story’ about memory decline that links language- and cultural-free items (blocks, digits) to more complex word recall. Combining different test items to form novel cognitive metrics, done carefully so not jeopardize validity and to enhance coherence in item design and purpose, is guided by entropy-based equivalence criteria identified in the CSEs. The novel NeuroMET Memory Metric may enable better-informed high stakes decision-making and more efficient and valid cognitive assessment.

[EN] The stupefying success of Artificial Intelligence (AI) for specific problems, from recommender systems to self-driving cars, has not yet been matched with a similar progress in general AI systems, coping with a variety of problems. This dissertation deals with the long-standing problem of creating more general AI systems, through the analysis of their development and the evaluation of their cognitive abilities.Firstly, this thesis contributes with a general-purpose learning system that meets several desirable characteristics in terms of expressiveness, comprehensibility and versatility. The system works with approaches that are inherently general: inductive programming and reinforcement learning. The system does not rely on a fixed library of learning operators, but can be endowed with new ones, so being able to operate in a wide variety of contexts. This flexibility, jointly with its declarative character, makes it possible to use the system as an instrument for better understanding the role (and difficulty) of the constructs that each task requires. The learning process is also overhauled with a new developmental and lifelong approach for knowledge acquisition, consolidation and forgetting, which is necessary when bounded resources (memory and time) are considered.Secondly, this thesis analyses whether the use of intelligence tests for AI evaluation is a much better alternative to most task-oriented evaluation approaches in AI. Accordingly, we make a review of what has been done when AI systems have been confronted against tasks taken from intelligence tests. In this regard, we scrutinise what intelligence tests measure in machines, whether they are useful to evaluate AI systems, whether they are really challenging problems, and whether they are useful to understand (human) intelligence. Finally, the analysis of the concepts of development and incremental learning in AI systems is done at the conceptual level but also through several of these intelligence tests, providing further insight for the understanding and construction of general-purpose developing AI systems., [ES] El éxito abrumador de la Inteligencia Artificial (IA) en la resolución de tareas específicas (desde sistemas de recomendación hasta vehículos de conducción autónoma) no ha sido aún igualado con un avance similar en sistemas de IA de carácter más general enfocados en la resolución de una mayor variedad de tareas. Esta tesis aborda la creación de sistemas de IA de propósito general así como el análisis y evaluación tanto de su desarrollo como de sus capacidades cognitivas. En primer lugar, esta tesis contribuye con un sistema de aprendizaje de propósito general que reúne distintas ventajas como expresividad, comprensibilidad y versatilidad. El sistema está basado en aproximaciones de carácter inherentemente general: programación inductiva y aprendizaje por refuerzo. Además, dicho sistema se basa en una biblioteca dinámica de operadores de aprendizaje por lo que es capaz de operar en una amplia variedad de contextos. Esta flexibilidad, junto con su carácter declarativo, hace que sea posible utilizar el sistema de forma instrumental con el objetivo de facilitar la comprensión de las distintas construcciones que cada tarea requiere para ser resuelta. Por último, el proceso de aprendizaje también se revisa por medio de un enfoque evolutivo e incremental de adquisición, consolidación y olvido de conocimiento, necesario cuando se trabaja con recursos limitados (memoria y tiempo).En segundo lugar, esta tesis analiza el uso de tests de inteligencia humana para la evaluación de sistemas de IA y plantea si su uso puede constituir una alternativa válida a los enfoques actuales de evaluación de IA (más orientados a tareas). Para ello se realiza una exhaustiva revisión bibliográfica de aquellos sistemas de IA que han sido utilizados para la resolución de este tipo de problemas. Esto ha permitido analizar qué miden realmente los tests de inteligencia en los sistemas de IA, si son significativos para su evaluación, si realmente constituyen problemas complejos y, por último, si son útiles para entender la inteligencia (humana). Finalmente se analizan los conceptos de desarrollo cognitivo y aprendizaje incremental en sistemas de IA no solo a nivel conceptual, sino también por medio de estos problemas mejorando por tanto la comprensión y construcción de sistemas de propósito general evolutivos., [CAT] L'èxit aclaparant de la Intel·ligència Artificial (IA) en la resolució de tasques específiques (des de sistemes de recomanació fins a vehicles de conducció autònoma) no ha sigut encara igualat amb un avanç similar en sistemes de IA de caràcter més general enfocats en la resolució d'una major varietat de tasques. Aquesta tesi aborda la creació de sistemes de IA de propòsit generalaixí com l'anàlisi i avaluació tant del seu desenvolupament com de les seues capacitats cognitives.En primer lloc, aquesta tesi contribueix amb un sistema d'aprenentatge de propòsit general que reuneix diferents avantatges com ara expressivitat, comprensibilitat i versatilitat. El sistema està basat en aproximacions de caràcter inherentment general: programació inductiva i aprenentatge per reforç. A més, el sistema utilitza una biblioteca dinàmica d'operadors d'aprenentatge pel que és capaç d'operar en una àmplia varietat de contextos. Aquesta flexibilitat, juntament amb el seu caràcter declaratiu, fa que siga possible utilitzar el sistema de forma instrumental amb l'objectiu de facilitar la comprensió de les diferents construccions que cada tasca requereix per a ser resolta. Finalment, el procés d'aprenentatge també és revisat mitjançant un enfocament evolutiu i incremental d'adquisició, consolidació i oblit de coneixement, necessari quan es treballa amb recursos limitats (memòria i temps).En segon lloc, aquesta tesi analitza l'ús de tests d'intel·ligència humana per a l'avaluació de sistemes de IA i planteja si el seu ús pot constituir una alternativa vàlida als enfocaments actuals d'avaluació de IA (més orientats a tasques). Amb aquesta finalitat, es realitza una exhaustiva revisió bibliogràfica d'aquells sistemes de IA que han sigut utilitzats per a la resolució d'aquest tipus de problemes. Açò ha permès analitzar què mesuren realment els tests d'intel·ligència en els sistemes de IA, si són significatius per a la seua avaluació, si realment constitueixen problemes complexos i, finalment, si són útils per a entendre la intel·ligència (humana). Finalment s'analitzen els conceptes de desenvolupament cognitiu i aprenentatge incremental en sistemes de IA no solament a nivell conceptual, sinó també per mitjà d'aquests problemes millorant per tant la comprensió i construcció de sistemes de propòsit general evolutius., Martínez Plumed, F. (2016). Incremental and developmental perspectives for general-purpose learning systems [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/67269., TESIS

Objective: P300-speller is the most commonly used brain-computer interface (BCI) for providing a means of communication to patients with amyotrophic lateral sclerosis. However, the performance of the P300-speller BCI is still inadequate. We investigated whether the performance of P300-speller can be further improved by increasing the mental effort required of the user.Methods: We designed two active mental tasks for a P300-speller based on a differently colored smiling cartoon-face paradigm. The tasks were based on color distinction, and their difficulty was modulated. One of the active mental tasks (DC task) required participants to focus on and distinguish the color of a target, while the other task (CN + DC task) required participants to simultaneously count the number of times a target flashed and distinguish its color.Results: The amplitudes of the event-related potentials (ERPs) in both DC and CN + DC tasks were higher than that in the CN task. The significant difference in the amplitudes between the DC and CN tasks was observed around the parietal-central area from 440 to 800 ms (late positive component, LPC), and that between the CN + DC and CN tasks was observed around the left-frontal and right-frontal areas from 320 to 480 ms (P3a) and the parietal-central area from 480 to 800 ms (P3b and LPC). The latency of the P300 potential in the CN + DC task was significantly longer than that in the CN task at F3, Fz, F4, C4, Pz, and P4 (P < 0.05). Offline (P < 0.05 at superposing once, twice, and thrice) and online (P < 0.001) classification results showed that the average accuracies in the CN + DC task were significantly greater than that in the CN task. Similar results were found for online information transfer rates (ITRs; P < 0.001). In addition, we found that the average online accuracies in the DC task were greater than those in the CN task, although the difference was not statistically significant (P = 0.051).Significance: The active mental task based on task difficulty modulation can significantly improve the performance of the P300-speller, and that based on color distinction shows a trend of improved performance.

Inhibition of return (IOR) refers to slower responses to targets that occur at a previously attended location than to those at control locations. Previous studies on the impact of task difficulty on IOR have shown conflicting results. However, these studies failed to match low-level characteristics of stimuli (e.g., size, color, and luminance) across difficulty levels, and so might have confounded the effect of task difficulty with that of stimulus characteristics. Hence, whether and how task difficulty modulates IOR remain largely unknown. This study utilized the event-related potentials (ERPs) technique in combination with a cue-target paradigm to tackle this question. Task difficulty was manipulated by changing the position of a gap in a rectangle stimulus, while stimulus size, color, and luminance were precisely matched. IOR was observed in reaction times across all difficulty levels but was found in accuracy at the medium level only. The modulation effect of task difficulty on IOR was also evident in the N1 and P2 ERP components, which showed significantly weaker IOR effects at the medium difficulty level than at the easy and hard levels. It is suggested that the modulation of IOR by task difficulty involves both perceptual and post-perceptual processes.

In specific dosages, the N-methyl-D-aspartate receptor (NMDA) antagonist ketamine can be used to model transient psychotic symptoms in healthy individuals that resemble those of schizophrenia. Ketamine administration also temporarily impairs cognitive functions, which can be studied by event-related potentials (ERPs). ERPs also allow dissecting what stages of information processing are affected by ketamine and what stages remain functional. For tasks requiring the differentiation of targets and non-targets, it has repeatedly been shown that ketamine administration in healthy individuals leads to decreased amplitudes of the ERP component P3b in response to target stimuli. However, it could be argued that this ketamine-induced P3b reduction is the consequence of an increased difficulty to differentiate targets from non-targets, primarily mediated by ketamine's psychotomimetic rather than pharmacological effects. The current review of ERP studies seeks to clarify the issue whether P3b effects of ketamine may indeed be explained as the consequence of an experienced increase in task difficulty or whether alternative mechanisms are perhaps more plausible. The review first summarizes the effects of task difficulty on ERP components related to intentional stimulus categorization (P3b), involuntary attention switches to distractors (P3a), as well as sensory processing (P1, N1). Secondly, the ERP effects of task difficulty are contrasted with those observed in ketamine studies in healthy individuals. Findings show that P3b amplitudes are consistently diminished by an increased task difficulty, as well as after ketamine administration. In contrast and as most important difference, increased task difficulty leads to increased P3a amplitudes to distractors presented in same modality as targets, whereas ketamine leads to reduced P3a amplitudes for such distractors. This dissociation indicates that the decreased P3b amplitudes after ketamine cannot be explained by a drug-induced increase in task difficulty. The conjoint reductions of P3a and P3b amplitudes instead suggest that working memory operations, in particular working memory updating are impaired after ketamine, which is in line with previous behavioral findings.

Two types of number magnitude processing - semantic and spatial - are significantly correlated with children's arithmetic performance. However, it remains unclear whether these abilities are independent predictors of symbolic approximate arithmetic performance. The current study addressed this question by assessing 86 kindergartners (mean age of 5 years and 7 months) on semantic number processing (number comparison task), spatial number processing (number line estimation task), and symbolic approximate arithmetic performance with different levels of difficulty. The results showed that performance on both tasks of number magnitude processing was significantly correlated with symbolic approximate arithmetic performance, but the strength of these correlations was moderated by the difficulty level of the arithmetic task. The simple symbolic approximate arithmetic task was equally related to both tasks. In contrast, for more difficult symbolic approximate arithmetic tasks, the contribution of number comparison ability was smaller than that of the number line estimation ability. These results indicate that the strength of contribution of the different types of numerical processing depends on the difficulty of the symbolic approximate arithmetic task.

Background Difficult cognitive tasks are often associated with negative feelings. This can be already the case for the mere anticipation of having to do a difficult task. For the case of difficult math tasks, it was recently suggested that such a negative emotional response may be exclusive to highly math-anxious individuals. However, it is also conceivable that negative emotional responses simply reflect that math is perceived as difficult. Here we investigated whether non-math-anxious individuals also experience negative emotional responses when anticipating to do difficult math tasks. Methods We compared brain activation following the presentation of a numerical cue indicating either difficult or easy upcoming proportion magnitude comparison tasks. Results Comparable to previous results for highly math-anxious individuals we observed a network associated with negative emotions to be activated in non-math-anxious individuals when facing cues indicating a difficult upcoming task. Importantly, however, math anxiety scores did not predict the neural response. Furthermore, we observed activation in areas associated with processes of cognitive control areas such as anterior cingulate cortex, which were suggested to play a key role in emotion regulation. Conclusion Activation in the emotion processing network was observed when anticipating an upcoming difficult (math) task. However, this activation was not predicted by individual’ degree of math anxiety. Therefore, we suggest that negative emotional responses to difficult math tasks might be a rather common reaction not specific to math-anxious individuals. Whether or not this initial negative response impairs math performance, however, might depend on the ability to regulate those emotions effectively. Electronic supplementary material The online version of this article (10.1186/s12993-019-0155-1) contains supplementary material, which is available to authorized users.

Social cognition (SC) and neurocognition appear to predict different aspects of functional outcome in people with schizophrenia. However, the correlations between performance on these domains have not been tested extensively and compared cross-diagnostically with healthy controls. Further, some social cognitive measures appeared to have potential ceiling effects, particularly for healthy people, in previous research, so increasing their difficulty is of interest. In this paper we report on two studies wherein we examined the correlations between neurocognitive ability and performance on SC tests. In the first study the correlations between measures of social perception, emotion processing, and theory of mind and performance on a brief neuropsychological (NP) assessment were examined in 179 schizophrenia (SCZ) patients and 104 healthy controls (HC). In the second study, we instructed participants to perform a subset of the tasks as rapidly as possible in order to increase task difficulty, and we examined the effects of those instructions on task difficulty, task psychometrics, and correlations between SC and NP tests in 218 SCZ patients and 154 HC. In the first study, both HC and SCZ manifested a domain specific pattern of correlation between NP and SC test performance. Controlling for group differences in NP performance did not eliminate SC performance differences between the groups. In the second study, no differences in task performance, intercorrelations other SC tests, or test-retest stability were induced by the difficulty manipulation in the samples who performed the tasks with speed demands compared to the performance of the previous sample. These data suggest that simple manipulations aimed at increasing task difficulty may not have the desired effect and that despite consistent correlations between SC and NP test performance, impairments in social cognitive functioning are not fully explained by NP performance deficits.

The aim was to determine whether there are differences between groups in jumping to conclusions and the number of beads required to make a decision based on task difficulty. An assessment was made of 19 patients with non-affective psychosis, 19 with obsessive–compulsive disorder (OCD), and 19 healthy controls. The Beads Task scale was used in its two versions. Patients with non-affective psychosis jumped to conclusions. There was significant interaction between group and task difficulty. Increased difficulty of the task did not affect the number of beads patients with non-affective psychosis or OCD needed to make their decision. However, healthy controls needed to see more beads before they could make a decision in the hard test than in the easy one. Patients with non-affective psychosis jump to conclusions, but neither this group nor the OCD patients benefit from the changes in task difficulty when making their decisions.

ResumoA teoria do ajuste regulatório estabelece que os consumidores se baseiam no seu foco motivacional (prevenção vs. promoção) para fazer avaliações de consumo e tomar decisões. Normalmente, os consumidores preferem produtos apresentados com o mesmo foco motivacional que o seu. Estudos anteriores mostram que esse padrão de preferência ocorre quando não somos motivados a processar informações. Porém, este estudo propõe que em situações que exigem maior esforço cognitivo, nas quais o consumidor precisa de mais informações para decidir, dada a dificuldade da tarefa, as mensagens que apresentem foco regulatório motivacional contrário ao do consumidor serão mais persuasivas. Dessa forma, os consumidores mostrarão maior intenção de comprar produtos apresentados em foco de não ajuste regulatório quando forem previamente expostos a tarefas difíceis, que exigem maior esforço cognitivo. O experimento 1 (n=257) mostra evidências da moderação da dificuldade da tarefa sobre a persuasão de mensagens de anúncios, enquanto o experimento 2 (n=144) apresenta este efeito em intenções de compra. Assim, nem sempre as informações compatíveis com o foco motivacional do consumidor são as mais bem avaliadas. Quando maior esforço cognitivo é requerido, mensagens de não ajuste com o foco regulatório motivacional poderão ser mais persuasivas. AbstractThe regulatory focus theory suggests that consumers rely on their motivational focus (prevention vs. promotion) for their evaluations and decisions. Usually consumers prefer products that match their personal motivational focus. Previous studies show that this pattern preferably occurs when we are not motivated to process information. However, this study suggests that situations that require greater cognitive effort, in which the consumer needs more information to decide because of the difficulty of the task, messages that have an opposing motivational regulatory focus will be more persuasive. When consumers have not been previously exposed to difficult tasks which require more cognitive effort, their willingness to buy products presented in ways that match their regulatory fit will increase. Experiment 1 (n=257) showed evidence that task difficulty has a moderating role in ad-message persuasiveness. Experiment 2 (n=144) presents the same moderating effect of task difficulty on the regulatory fit (vs unfit) phenomenon for willingness to buy. Therefore, not all information compatible with consumer motivational focus is well evaluated. When greater cognitive effort is required, unfit messages may be more persuasive.

In this article, we outline our view of how concentration shields against distraction. We argue that higher levels of concentration make people less susceptible to distraction for two reasons. One reason is that the undesired processing of the background environment is reduced. For example, when people play a difficult video game, as opposed to an easy game, they are less likely to notice what people in the background are saying. The other reason is that the locus of attention becomes more steadfast. For example, when people are watching an entertaining episode of their favorite television series, as opposed to a less absorbing show, attention is less likely to be diverted away from the screen by a ringing telephone. The theoretical underpinnings of this perspective, and potential implications for applied settings, are addressed.

Many aspects of the complex relationship between working memory (WM) and long-term memory (LTM) remain unclear. Here, we manipulated task demands on a brief delayed-recognition paradigm to reveal behavioral and neural dissociations between these systems. Variations from a Baseline task included 3 challenges: increased delay duration, distraction during maintenance, and more closely matched memory probes, which were presented in behavioral experiments and during functional magnetic resonance imaging. Each of the challenges resulted in a significant decline in WM accuracy, and interestingly, a concurrent improvement in incidental LTM. Neural data revealed that, in task blocks, when participants anticipated, and then experienced, increased demands, they engaged medial temporal lobe (MTL) regions more during both the encoding and delay periods. Overall, these results indicate that distinct memory systems are recruited based on anticipated demands of a memory task, and MTL involvement underlies the observed dissociation between WM and LTM performance.

In adults, the disrupting effect of irrelevant background sounds with distinct temporalspectral variations (changing-state sounds) on short-term memory performance was found to be robust. In the present study, a verbal serial recognition task was used to investigate this so-called Irrelevant Sound Effect (ISE) in adults and 8- to 10-year-old children. An essential part of the short-term memory impairment during changing-state speech is due to interference processes (changing-state effect) which can be differentiated from the deviation effect of auditory distraction. In line with recent findings (Hughes et al., 2013), our study demonstrates that the changing-state effect is not modulated by task difficulty. Moreover, our results show that the changing-state effect remains stable for children and adults. This suggests that the differences in the magnitude of the ISE as reported by Elliott (2002) and Klatte et al. (2010) are most likely related to the increase in attentional control during childhood.

Musicians are highly trained to discriminate fine pitch changes but the neural bases of this ability are poorly understood. It is unclear whether such training-dependent differences in pitch processing arise already in the subcortical auditory system or are linked to more central stages. To address this question, we combined psychoacoustic testing with functional MRI to measure cortical and subcortical responses in musicians and non-musicians during a pitch-discrimination task. First, we estimated behavioral pitch-discrimination thresholds for complex tones with harmonic components that were either resolved or unresolved in the auditory system. Musicians outperformed non-musicians, showing lower pitch-discrimination thresholds in both conditions. The same participants underwent task-related functional MRI, while they performed a similar pitch-discrimination task. To account for the between-group differences in pitch-discrimination, task difficulty was adjusted to each individual's pitch-discrimination ability. Relative to non-musicians, musicians showed increased neural responses to complex tones with either resolved or unresolved harmonics especially in right-hemispheric areas, comprising the right superior temporal gyrus, Heschl's gyrus, insular cortex, inferior frontal gyrus, and in the inferior colliculus. Both subcortical and cortical neural responses predicted the individual pitch-discrimination performance. However, functional activity in the inferior colliculus correlated with differences in pitch discrimination across all participants, but not within the musicians group alone. Only neural activity in the right auditory cortex scaled with the fine pitch-discrimination thresholds within the musicians. These findings suggest two levels of neuroplasticity in musicians, whereby training-dependent changes in pitch processing arise at the collicular level and are preserved and further enhanced in the right auditory cortex.

We investigated whether the late posterior negativity (LPN) is a component linked to stimulus retrieval or rather to complex, higher-order stimulus evaluation processes or response preparation processes. Participants performed three separate tasks across separate sessions: an encoding task, a memory recognition task, and a visual discrimination task. In the visual discrimination task, the difficulty of stimulus evaluation was manipulated via stimuli varying in complexity (easy vs. moderately difficult) and duration of stimulus presentation (short vs. long). Three indices of the LPN peak were examined: amplitude, latency, and width. The LPN was present in all three tasks, with maximum amplitudes at occipital sites. Results of the visual discrimination task showed that the LPN amplitude is modulated by task difficulty. No latency differences were observed between short and long presentations, suggesting that the LPN is not related to response preparation. Consequently, we compared the LPN associated with short presentations of easy and difficult stimuli with the LPN of the encoding and memory task. The LPN amplitude was more negative in the memory task compared to the other tasks. Latency and width of the LPN were modulated by stimulus complexity, with increased latency and width in the encoding and memory task relative to the visual discrimination task. Overall, these findings suggest that the LPN is not a component linked to stimulus retrieval and response preparation, but rather to complex, higher-order stimulus evaluation processes, which are modulated by task difficulty.

Previous research has shown a wide array of age-related declines in vision. The current study examined the effects of perceptual learning (PL), external noise, and task difficulty in fine orientation discrimination with older individuals (mean age 71.73, range 65–91). Thirty-two older subjects participated in seven 1.5-h sessions conducted on separate days over a three-week period. A two-alternative forced choice procedure was used in discriminating the orientation of Gabor patches. Four training groups were examined in which the standard orientations for training were either easy or difficult and included either external noise (additive Gaussian noise) or no external noise. In addition, the transfer to an untrained orientation and noise levels were examined. An analysis of the four groups prior to training indicated no significant differences between the groups. An analysis of the change in performance post-training indicated that the degree of learning was related to task difficulty and the presence of external noise during training. In addition, measurements of pupil diameter indicated that changes in orientation discrimination were not associated with changes in retinal illuminance. These results suggest that task difficulty and training in noise are factors important for optimizing the effects of training among older individuals.

In this paper, we apply the basic idea of a trade-off between the level of concentration and distractibility to test whether a manipulation of task difficulty can shield against distraction. Participants read, either in quiet or with a speech noise background, texts that were displayed either in an easy-to-read or a hard-to-read font. Background speech impaired prose recall, but only when the text was displayed in the easy-to-read font. Most importantly, recall was better in the background speech condition for hard-to-read than for easy-to-read texts. Moreover, individual differences in working memory capacity were related to the magnitude of disruption, but only in the easy-to-read condition. Making a task more difficult can sometimes facilitate selective attention in noisy work environments by promoting focal-task engagement. © 2014 The Authors.

Background: Visual search declines with aging, dementia, and brain injury and is linked to limitations in everyday activities. Recent studies suggest that visual search can be improved with practice using computerized visual search tasks and puzzle video games. For practical use, it is important that visual search ability can be assessed and practiced in a controlled and adaptive way. However, commercial puzzle video games make it hard to control task difficulty, and there are little means to collect performance data. Objective: The aim of this study was to develop and initially validate the search and match task (SMT) that combines an enjoyable tile-matching match-3 puzzle video game with features of the visual search paradigm (taskified game). The SMT was designed as a single-target visual search task that allows control over task difficulty variables and collection of performance data. Methods: The SMT is played on a grid-based (width × height) puzzle board, filled with different types of colored polygons. A wide range of difficulty levels was generated by combinations of 3 task variables over a range from 4 to 8 including height and width of the puzzle board (set size) and the numbers of tile types (distractor heterogeneity). For each difficulty level, large numbers of playable trials were pregenerated using Python. Each trial consists of 4 consecutive puzzle boards, where the goal of the task is to find a target tile configuration (search) on the puzzle board and swap 2 adjacent tiles to create a line of 3 identical tiles (match). For each puzzle board, there is exactly 1 possible match (single target search). In a user study with 28 young adults (aged 18 to 31 years), 13 older (aged 64 to 79 years) and 11 oldest (aged 86 to 98 years) adults played the long (young and older adults) or short version (oldest adults) of the difficulty levels of the SMT. Participants rated their perception and the usability of the task and completed neuropsychological tests that measure cognitive domains engaged by the puzzle game. Results: Results from the user study indicate that the target search time is associated with set size, distractor heterogeneity, and age. Results further indicate that search performance is associated with general cognitive ability, selective and divided attention, visual search, and visuospatial and pattern recognition ability. Conclusions: Overall, this study shows that an everyday puzzle game–based task can be experimentally controlled, is enjoyable and user-friendly, and permits data collection to assess visual search and cognitive abilities. Further research is needed to evaluate the potential of the SMT game to assess and practice visual search ability in an enjoyable and adaptive way. A PsychoPy version of the SMT is freely available for researchers.

Proficiency in arithmetic learning can be achieved by using a multitude of strategies, the most salient of which are procedural learning (applying a certain set of computations) and rote learning (direct retrieval from long-term memory). Here we investigated the effect of transcranial random noise stimulation (tRNS), a non-invasive brain stimulation method previously shown to enhance cognitive training, on both types of learning in a 5-day sham-controlled training study, under two conditions of task difficulty, defined in terms of item repetition. On the basis of previous research implicating the prefrontal and posterior parietal cortex in early and late stages of arithmetic learning, respectively, sham-controlled tRNS was applied to bilateral prefrontal cortex for the first 3 days and to the posterior parietal cortex for the last 2 days of a 5-day training phase. The training involved learning to solve arithmetic problems by applying a calculation algorithm; both trained and untrained problems were used in a brief testing phase at the end of the training phase. Task difficulty was manipulated between subjects by using either a large (“easy” condition) or a small (“difficult” condition) number of repetition of problems during training. Measures of attention and working memory were acquired before and after the training phase. As compared to sham, participants in the tRNS condition displayed faster reaction times and increased learning rate during the training phase; as well as faster reaction times for both trained and untrained (new) problems, which indicated a transfer effect after the end of training. All stimulation effects reached significance only in the “difficult” condition when number of repetition was lower. There were no transfer effects of tRNS on attention or working memory. The results support the view that tRNS can produce specific facilitative effects on numerical cognition – specifically, on arithmetic learning. They also highlight the importance of task difficulty in the neuromodulation of learning, which in the current study due to the manipulation of item repetition might have being mediated by the memory system., Highlights • tRNS was previously shown to enhance cognitive training in an arithmetical task. • 5-day training on Calculation and Drill arithmetic was accompanied by tRNS to PFC&PPC. • Task difficulty was manipulated by including fewer or more problems in training. • tRNS improved Calculation training performance & led to transfer in testing phase. • tRNS effects were seen only in the difficult task condition.

In visual conflict tasks (e.g., Stroop or flanker), response times (RTs) are generally longer on incongruent trials relative to congruent ones. Two event-related-potential (ERP) components classically associated with the processing of stimulus conflict are the fronto-central, incongruency-related negativity (Ninc) and the posterior late-positive complex (LPC), which are derived from the ERP difference waves for incongruent minus congruent trials. It has been questioned, however, whether these effects, or other neural measures of incongruency (e.g., fMRI responses in the anterior cingulate), reflect true conflict processing, or whether such effects derive mainly from differential time-on-task. To address this question, we leveraged high-temporal-resolution ERP measures of brain activity during two behavioral tasks. The first task, a modified Erikson flanker paradigm (with congruent and incongruent trials), was used to evoke the classic RT and ERP effects associated with conflict. The second was a non-conflict control task in which, participants visually discriminated a single stimulus (with easy and hard discrimination conditions). Behaviorally, the parameters were titrated to yield similar RT effects of conflict and difficulty (27 ms). Neurally, both within-task contrasts showed an initial fronto-central negative-polarity wave (N2-latency effect), but they then diverged. In the difficulty difference wave, the initial negativity led directly into the posterior LPC, whereas in the incongruency contrast the initial negativity was followed a by a second fronto-central negative peak (Ninc), which was then followed by a considerably longer-latency LPC. These results provide clear evidence that the longer processing for incongruent stimulus inputs do not just reflect time-on-task or difficulty, but include a true conflict-processing component.

International audience; The present study tested the hypothesis of an additive interaction between intrinsic, extraneous and germane cognitive load, by manipulating factors of mental workload assumed to have a specific effect on either type of cognitive load. The study of cognitive load factors and their interaction is essential if we are to improve workers' wellbeing and safety at work. High cognitive load requires the individual to allocate extra resources to entering information. It is thought that this demand for extra resources may reduce processing efficiency and performance. The present study tested the effects of three factors thought to act on either cognitive load type, i.e. task difficulty, time pressure and alertness in a working memory task. Results revealed additive effects of task difficulty and time pressure, and a modulation by alertness on behavioral, subjective and psychophysiological workload measures. Mental overload can be the result of a combination of task-related components, but its occurrence may also depend on subject-related characteristics, including alertness. Solutions designed to reduce incidents and accidents at work should consider work organization in addition to task constraints in so far that both these factors may interfere with mental workload.

No theory of driver behaviour has yet managed to achieve widespread acceptance and use in the field of Traffic Psychology, partly due to the difficulty in testing many of the theories. However, one class of theories, the motivational theories, can be usefully split into two groups and the differences between them can then be examined. One group posits the constant monitoring and targeting of a certain subjective variable, often risk, as the controlling factor in driving. The other group however states that subjective variables such as risk are only relevant once a certain threshold has been passed.In this study we aimed to examine this difference by manipulating both speed of travel and the amount of cognitive load participants were under. Participants were asked to initially drive at their preferred speed for 1 min in a driving simulator. Participant's speed was then automatically increased or decreased by 10, 20 30 km/h or left unchanged. Participants were then required to maintain the new speed for 1 min. After this 1 min the speed was again automatically changed and had to be maintained for one more minute, but this time participants also carried out a secondary mental arithmetic task. Finally participants were asked to again drive for another 1 min at their preferred speed. This procedure was repeated seven times, once for each speed manipulation; -30, -20, -10, +0, +10, +20 and +30 km/h. After each 1 min interval verbal ratings of task difficulty, effort, feeling of risk and the typicality of the speed were collected.The results show a threshold effect in ratings of task difficulty, effort and feeling of risk, with no significant difference given between the ratings during the baseline period and the experimentally decreased speed periods until after participant's preferred speed of travel had been exceeded. Furthermore, even when under cognitive load the threshold relationship was still apparent, if diminished. Finally it appears that when under cognitive load drivers have difficulty maintaining a travelling speed which is lower than the speed at which they would prefer to drive. However, driving at a speed in excess of their preferred speed appears to be easier to maintain, at least in the short term. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract. Although it is often assumed that the left and right cerebral hemispheres are specialized for local and global processing, respectively, recent studies show that this difference mainly occurs if the responses to the two levels of a stimulus are conflicting. In the present study we examined whether the favorable effect of response conflicts is caused by the increased task difficulty in this situation. To this end, the response selection for nonconflicting stimuli was complicated by frequently changing the stimulus-response mappings. As a result, the reactions to nonconflicting stimuli were as slow as those to conflicting ones. Nevertheless, hemispheric differences were again restricted to the latter situation. This shows that increased task difficulty can not explain the modulating effect of response conflicts. The results support the alternative hypothesis that different representations are needed for the response selection for nonconflicting and conflicting stimuli, and that the hemispheres differ only with respect to the latter.

This paper presents a method for analyzing users' computer mouse interaction data with the aim to implicitly identify task completion difficulty while interacting with a system. Computer mouse motion streams and users' skin conductance signals, acquired via an in-house developed computer mouse, and users' feedback were investigated as reactions to task difficulty raising events. A classification algorithm was developed, producing real-time user models of user hesitation states. Preliminary results of a study in progress with seven older adults at work (age 56+) provide initial indications about links between mouse triggering states of user hesitation and task completion difficulty. Copyright is held by the author/owner(s). 18 1019 1024 Sponsors: ACM Special Interest Group on Computer-Human Interaction (ACM SIGCHI) Conference code: 116996 Cited By :4

Pri inteligentnih tutorskih sistemih je pomembno, da sistem razume, kako težak je določen problem za učenca. Kako samodejno oceniti tovrstno težavnost, ostaja odprto vprašanje. Namen raziskave je razviti algoritmičen pristop k ugotavljanju težavnosti, ki bi ga lahko uporabljali pri avtomatiziranem ocenjevanju težavnosti problemov za človeka. Osredotočili se bomo na ocenjevanje težavnosti problemov, pri katerih težavnost izvira iz kombinatorične kompleksnosti in kjer je potrebno preiskovanje med alternativami. Pristop temelji na uporabi hevrističnega računalniškega preiskovanja za gradnjo preiskovalnih dreves, ki so ``smiselna'' z vidika osebe, ki problem rešuje. Pokazali bomo, da je s pomočjo analize lastnosti tovrstnih ``smiselnih'' dreves računalniški program sposoben napovedati, kako težak za reševanje je določen problem. Naš program je bil sposoben z visoko stopnjo natančnosti ločevati med enostavnimi in težkimi šahovskimi taktičnimi problemi. In intelligent tutoring systems, it is important for the system to understand how difficult a problem is for the student. However, it is an open question how to automatically assess such difficulty. The aim of our research is to find formalized measures of difficulty that could be used in automated assessment of the difficulty of a mental task for a human. We present a computational approach to estimating the difficulty of problems in which the difficulty arises from the combinatorial complexity of problems where a search among alternatives is required. Our approach is based on a computer heuristic search for building search trees that are “meaningful” from a human's point of view. We demonstrate that by analyzing properties of such trees, the program is capable to predict how difficult it would be for a human to solve the problem. In the experiments with chess tactical problems our program was able to differentiate between easy and difficult problems with a high level of accuracy.

The residual consciousness of unconscious patients can be detected by studying the P300, a wave among event-related potentials. Previous studies have applied tones, the subject's name and other names as stimuli. However, the results were not satisfactory. In this study, we changed the constituent order of subjects' two-character names to create derived names. The subject's derived names, together with tones and their own names, were used as auditory stimuli in event-related potential experiments. Healthy controls and unconscious patients were included in this study and made to listen to these auditory stimuli. In the two paradigms, a sine tone followed by the subject's own name and the subject's derived name followed by the subject's own name were used as standard and deviant stimuli, respectively. The results showed that all healthy controls had the P300 using both paradigms, and that the P300 in the second paradigm had a longer latency and two peaks. All minimally conscious state patients had the P300 in the first paradigm and the majority of them had the P300 in the second paradigm. Most vegetative state patients had no P300. Patients who showed the P300 in the two paradigms had more residual consciousness, and patients with the two-peak P300 had a higher probability of awakening within a short time. Our experimental findings suggest that the P300 event-related potential could reflect the conscious state of unconscious patients.

The present research experiment, which mostly used undergrad university students as subjects, was aimed to investigate how instant rewards / no rewards affect task performance on easy and difficult memorization tasks. A list with easy and a list with complicated words were created as audio files, and participants had to listen to either one, then recall and write down as many as they could. One condition received chocolate eggs as reward for each correct word, the other condition did not. After collecting data from 40 subjects (with 10 in each correlational design group: easy/reward, easy/no reward, difficult/reward, difficult/no reward), an ANOVA done with SPSS revealed that there was a significant main effect of rewards, F (1, 36) = 8.42, p < .05, as well as due to difficulty, F (1, 36) = 21.55, p < .05. No interactions were found. The assumption is that the results came to be due to the nature of the rewards and the kind of task. Opinions, ideas and future proposed research on the topic are further discussed in the Discussion section of this research report.

Previous studies of the Stroop task propose two key mediators: the prefrontal and cingulate cortices but hints exist of functional specialization within these regions. This study aimed to examine the effect of task modality upon the prefrontal and cingulate response by examining the response to colour, number, and shape Stroop tasks whilst BOLD fMRI images were acquired on a Siemens 3 T MRI scanner. Behavioural analyses indicated facilitation and interference effects and a noticeable effect of task difficulty. Some modular effects of modality were observed in the prefrontal cortex that survived exclusion of task difficulty related activations. No effect of task-relevant information was observed in the anterior cingulate. Future comparisons of the mediation of selective attention need to consider the effects of task context and task difficulty.

Motion repulsion involves interaction between two directions of motion. Since attention is known to bias interactions among different stimuli, we investigated the effect of attentional tasks on motion repulsion. We used two overlapping sets of random dots moving in different directions. When subjects had to detect a small speed-change or luminance change for dots along one direction, the repulsive influence from the other direction was significantly reduced compared with the control case without attentional tasks. However, when the speed-change could occur to either direction such that subjects had to attend both directions to detect the change, motion repulsion was not different from the control. A further experiment showed that decreasing the difficulty of the attentional task resulted in the disappearance of the attentional effect in the case of attention to one direction. Finally, over a wide range of contrasts for the unattended direction, attention reduced repulsion measured with the attended direction. These results are consistent with the physiological finding that strong attention to one direction of motion reduces inhibitory effects from the other direction.

We studied perceptual learning in motion discrimination when the brain's middle temporal area (MT/V5) was functionally suppressed. This was achieved by using the “paired-dots” motion stimulus where the two dots in a pair always move in counter-phase over a short distance [J. Neurosci. 14 (1994) 7357]. The motion directional signal of the stimulus is therefore always 0 on average. As a result, this stimulus activates MT in Rhesus monkeys no more than flicker noise does [J. Neurosci. 14 (1994) 7367]. We added a new manipulation to eliminate the Glass pattern in the original stimulus that would have otherwise provided a static orientation cue. Two such new motion stimuli were presented sequentially, in a 2AFC task. Subjects decided if the global motion-axis of the stimuli changed clockwise or counter-clockwise. When the task difficulty was set at 60% correct, none of the subjects could learn with feedback, even though their performance was well above chance. However, when the task difficulty was set instead at 70% correct, a new group of subjects was able to learn. Hence, learning motion discrimination was possible when MT was presumably eliminated.

Directing attention to a specific feature of an object has been linked to different forms of attentional modulation. Object-based attention theory founds on the finding that even task-irrelevant features at the selected object are subject to attentional modulation, while feature-based attention theory proposes a global processing benefit for the selected feature even at other objects. Most studies investigated either the one or the other form of attention, leaving open the possibility that both object- and feature-specific attentional effects do occur at the same time and may just represent two sides of a single attention system. We here investigate this issue by testing attentional spreading within and across objects, using reaction time (RT) measurements to changes of attended and unattended features on both attended and unattended objects. We asked subjects to report color and speed changes occurring on one of two overlapping random dot patterns (RDPs), presented at the center of gaze. The key property of the stimulation was that only one of the features (e.g., motion direction) was unique for each object, whereas the other feature (e.g., color) was shared by both. The results of two experiments show that co-selection of unattended features even occurs when those features have no means for selecting the object. At the same time, they demonstrate that this processing benefit is not restricted to the selected object but spreads to the task-irrelevant one. We conceptualize these findings by a 3-step model of attention that assumes a task-dependent top-down gain, object-specific feature selection based on task- and binding characteristics, and a global feature-specific processing enhancement. The model allows for the unification of a vast amount of experimental results into a single model, and makes various experimentally testable predictions for the interaction of object- and feature-specific processes.

The present study was designed to measure the effects of task difficulty and reward opportunity on motivation. The participants, 20 undergraduate students, were randomly assigned to one of four experimental conditions: reward opportunity-hard proofreading task, reward opportunity-easy proofreading task, no reward opportunity-hard proofreading task, or no reward opportunity-easy proofreading task. It was hypothesized that the participants offered an opportunity for reward would perform better than those not offered an opportunity for reward by indicating and correcting more spelling and grammatical errors. Also, it was hypothesized that participants offered an opportunity for reward would return the completed proofreading task quicker than participants not offered an opportunity for reward. Two, 2 x 2 ANOVAs were carried out with the results showing no main effects of task difficulty or opportunity for reward on number of errors corrected or time of return (in days), indicating no change in motivation. As the original hypothesis was not supported, issues with the study and areas for further research were discussed.

In this study we examined whether effects of perceptual load on the attentional selectivity are modulated by degradation of the visual input. According to the perceptual load theory, increasing task difficulty via degradation of stimulus visibility should not alter the typical effect of perceptual load. In previous studies only the target was degraded, resulting in increased distractor saliency. Here we combined manipulation of perceptual load with a more systematic degradation of visual information. Experiment 1 included five conditions. Three conditions involved low perceptual load + contrast reduction of: a) only the target; b) only the distractor; c) both target and distractor. The other two conditions included non-degraded stimuli with low or high perceptual load. In Experiment 2 visibility degradation was established via manipulation of exposure duration. It included two exposure durations – 100 ms and 150 ms – for each load level (low vs. high). The results of both experiments demonstrated reliable distractor interference of a similar magnitude with both degraded and non-degraded stimuli. This finding suggests that task difficulty, when manipulated via degradation of stimulus visibility, does not play a critical role in determining the efficiency of the attentional selectivity. However, contrary to the predictions of the perceptual load theory, in both experiments distractor interference emerged under the high load condition. In Experiment 2 the high-load interference was of the same magnitude as that of the low load condition. This high-load interference is not due to the presence of a mask (Experiment 3) or a mixed design (Experiment 4). These findings suggest that perceptual load may also play a lesser role in attentional selectivity than that assigned to it by the perceptual load theory.