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Purpose: Individuals with cortical visual impairment (CVI) can have difficulties with visual processing due to physical damage or atypical structures of visual pathways or visual processing centers in the brain. Many individuals with CVI have concomitant disabilities, including significant communication support needs; these individuals can benefit from augmentative and alternative communication (AAC). Because much AAC involves a visual channel, implementation of AAC must consider the unique visual processing skills and challenges in CVI. However, little is known empirically about how to best design AAC for individuals with CVI. This study examined processing of visual stimuli in four young adolescents with CVI. Method: This study used a within-subjects experimental design that sought to provide an in-depth description of the visual engagement of individuals with CVI when viewing stimuli of various levels of complexity, either with or without a social cue. Results: Participants engaged most with the simplest stimuli (relative to the size of those stimuli) and engaged more when a social cue was provided during the task. The level of engagement with more complex stimuli was related to participants' score on the CVI Range, a clinical assessment tool that characterizes level of visual functioning. Conclusions: Implications for AAC include considerations for the internal complexity of AAC symbols and the complexity of the arrays created for individuals with CVI. Clinicians working with children with CVI who use AAC should consider the unique features of their visual processing.

Neuroimaging MEG data (recogatonal_all_conditions.mat and recogmajor_all_conditions.mat) and source data for each of the four conditions (tonal 0.1 -1 Hz frequency band,tonal 2-8Hz frequency band, atonal 0.1 -1 Hz frequency band, and atonal 2-8Hz frequency band).

Why do people like images of neatly organized compositions, collected on blogs like Things Organized Neatly? (http://thingsorganizedneatly.tumblr.com/) We explored which factors might contribute to aesthetic preferences for these images of a set of objects, or parts of objects, organized in a neatly or tidy way, focusing on both stimulus and person properties related to order, complexity, and the balance between order and complexity. In a large-scale online study, 421 participants chose which of two simultaneously presented images they preferred (100 pairs) and completed some personality questionnaires. The images within each pair were selected to be very similar except for how ordered and/or complex they were on certain perceptual dimensions. In a second part of the study, 84 of these participants also rated how ordered, complex, soothing, and fascinating they found the 184 images. Images high in order and high in complexity were perceived as more fascinating, whereas images high in order but low in complexity were perceived as more soothing. Aesthetic preferences increased with increasing differences in soothingness and fascination between the two images. Subjective order and subjective complexity were both related to aesthetic appreciation, and independently so, suggesting that the balance between order and complexity involves no interaction. Participants differed in how often they preferred the more ordered, complex, soothing, and fascinating image in a pair, which could partly be attributed to age and personality. In general, stimulus and person interact in determining aesthetic appreciation, but deeper theoretical understanding of these interactions requires further investigation with more parametrically varied stimuli. ispartof: Psychology of Aesthetics, Creativity, and the Arts vol:15 issue:3 pages:484-504 status: Published online

The complexity of an environment is an important factor related to the quality of urban life, as it affects perception. Existing methods for estimating complexity from images or field visits are helpful but difficult to apply when the area of interest is large. This study identifies alternative ways of estimating the complexity of an environment, by analysing the density of Points of Interest (POI) of an area and using it as an indicator of mixed land use. Two case studies are explored, and spatial regression models are employed to test the association between POI density and complexity, and its predictors.

The capacity of visual working memory (VWM) depends on the complexity of the stimuli being processed. Emotional characteristics increase stimulus complexity and can interfere with the competition for cognitive resources. Studies involving emotional information processing are scarce and still produce contradicting results. In the present study, we investigated the capacity of VWM for faces with positive, negative, and neutral expressions. A modified change-detection task was used in two experiments, in which the number of faces and the emotional valence were manipulated. The results showed that VWM has a storage capacity of approximately two faces, which is fewer than the storage capacity identified for simpler stimuli. Our results reinforce the evidence that working memory can dynamically distribute its storage resources depending on both the amount and the emotional nature of the stimuli.

Experimental psychology 68(3), 149-164 (2021). doi:10.1027/1618-3169/a000520, Published by Hogrefe & Huber, Göttingen

Journal of cognition 3(1), 30 (2020). doi:10.5334/joc.115 special issue: "The state-of-the-art of research into human multitasking / Guest Editors: Leif Johannsen, Institute of Psychology, RWTH Aachen University, Germany; Andrea Kiesel, Institute of Psychology, Albert Ludwig University of Freiburg; Iring Koch, Institute of Psychology, RWTH Aachen University, Germany", Published by Ubiquity Press, London

The left hemisphere is known to be generally predominant in verbal processing and the right hemisphere in non-verbal processing. We studied whether verbal and non-verbal lateralization is present in haptics by comparing discrimination performance between letters and nonsense shapes. We addressed stimulus complexity by introducing lower case letters, which are verbally identical with upper case letters but have a more complex shape. The participants performed a same-different haptic discrimination task for upper and lower case letters and nonsense shapes with the left and right hand separately. We used signal detection theory to determine discriminability (d '), criterion (c) and we measured reaction times. Discrimination was better for the left hand for nonsense shapes, close to significantly better for the right hand for upper case letters and with no difference between the hands for lower case letters. For lower case letters, right hand showed a strong bias to respond "different", while the left hand showed faster reaction times. Our results are in agreement with the right lateralization for non-verbal material. Complexity of the verbal shape is important in haptics as the lower case letters seem to be processed as less verbal and more as spatial shapes than the upper case letters.

Mental rotation (MR) is the ability to imagine the appearance of an object from a different perspective. This ability is involved in many human cognitive and behavioral activities. We discuss studies that have examined MR in infants and its development across the first year after birth. Despite some conflicting findings across these studies, several conclusions can be reached. First, MR may be available to human infants as young as 3 months of age. Second, MR processes in infancy may be similar or identical to MR processes later in life. Third, there may be sex differences in MR performance, in general favoring males. Fourth, there appear to be multiple influences on infants' MR performance, including infants' motor activity, stimulus complexity, hormones, and parental attitudes. We conclude by calling for additional research to examine more carefully the causes and consequences of MR abilities early in life.

Although it is well accepted that the formation of visual working memory (VWM) representations from simple static features is a rapid and effortless process that completes within several hundred milliseconds, the storage of motion information in VWM within that time scale can be challenging due to the limited processing capacity of the visual system. Memory formation can also be demanding especially when motion stimuli are visually complex. Here, we investigated whether the formation of VWM representations of motion direction is more gradual than that of static orientation and examined the effects of stimulus complexity on that process. To address these issues, we examined how the number and the precision of stored items in VWM develop over time by using a continuous report procedure. Results showed that while a viewing duration of several seconds was required for the successful storage of multiple motion directions in VWM regardless of motion complexity, the accumulation of memory precision was much slower when the motion stimulus was visually complex (Experiments 1 & 2). Additional experiments showed that the difference in memory performance for simple and complex motion stimuli cannot be explained by differences in signal-to-noise levels of the stimulus (Experiment 3). These results demonstrate remarkable temporal limitations in the formation of VWM representations for dynamic objects, and further show how this process is affected by stimulus properties such as visual complexity and signal-to-noise levels.

Frequency following responses (FFRs) can be evoked by a wide range of auditory stimuli, but for many stimulus parameters the effect on FFR strength is not fully understood. This complicates the comparison of earlier studies and the design of new studies. Furthermore, the most optimal stimulus parameters are unknown. To help resolve this issue, we investigated the effects of four important stimulus parameters and their interactions on the FFR. FFRs were measured in 16 normal hearing subjects evoked by stimuli with four levels of stimulus complexity (amplitude modulated noise, artificial vowels, natural vowels and nonsense words), three frequencies (around 105 Hz, 185 Hz and 245 Hz), three frequency contours (upward sweeping, downward sweeping and flat) and three vowels (Flemish /a:/, /u:/, and /i:/). We found that FFRs evoked by artificial vowels were on average 4 to 6 dB SNR larger than responses evoked by the other stimulus complexities, probably because of (unnaturally) strong higher harmonics. Moreover, response amplitude decreased with stimulus frequency but response SNR did not. Thirdly, frequency variation within the stimulus did not impact FFR strength, but only when rate of change remained low (e.g. not the case for sweeping natural vowels). Finally, the vowel /i:/ appeared to evoke larger response amplitudes compared to /a:/ and /u:/, but analysis power was too small to confirm this statistically. Differences in response strength between evoking vowels have been suggested to stem from destructive interference between response components. We show how a model of the auditory periphery can simulate these interference patterns and predict response strength. Altogether, the results of this study can guide stimulus choice for future FFR research and practical applications.

The form of mental images in congenitally blind people is intensely debated by researchers. In order to get a better insight into this topic, we conducted an experiment during which the task for congenitally blind individuals was to learn 2D tactile shapes and then mentally rotate them. The control group consisted of blindfolded sighted individuals. The visuo-spatial working memory model was treated as a theoretical framework for the theoretical debate. The aim of the study was to determine whether the accuracy of mental rotation is lower in congenitally blind than in sighted individuals and whether the difference in accuracy between the groups depends on the complexity of tactile figures. We also tested if the complexity of the figure and the background (grid or frame) influences the passive and active components of visuo-spatial working memory. Results show that congenitally blind subjects learned the shapes of figures by touch and rotated them faster than sighted subjects. It was established that the learning time depends on the complexity of figures and backgrounds. Figures presented on a complex background of a grid required more time to learn then figures in a frame. Moreover, sighted individuals required more time to learn complex figures than they did to learn simple ones. This was not the case with the congenitally blind. The rotation task was performed with greater accuracy for figures presented on a plain background compared to the complex background, and faster for figures drawn in a frame than for those on a grid. The study has shown that the active component of the visuo-spatial working memory engaged during mental rotation works with at least equal efficiency in congenitally blind individuals compared to sighted ones.

Debate continues over whether visual working memory has a single, fixed capacity. Empirically, performance in working memory tasks worsens as the complexity of stimuli increases. However, there exist two explanations for this result. One proposal is that visual working memory is capable of holding fewer complex stimuli. The alternative proposal is that visual working memory can store 3–4 items, irrespective of their complexity. According to this fixed-capacity explanation, performance is worse for complex items because discrimination between complex items is more difficult than discrimination between simple items. These so-called comparison errors are more likely with complex items, and when left unaccounted for, lead to an underestimate of the capacity of working memory. Previous attempts at resolving this debate have relied on clever empirical manipulations of the similarity between stimuli. However, such approaches change the task that is given to the participant, and so may also change the way that participants use their memory. Here, we use a standard change detection task, but use a measurement model to estimate both the capacity of memory, and the probability of comparison errors. We apply the model to two change detection experiments in which we varied the complexity of the stimuli that participants must remember. Critically, we found that capacity estimates, and not comparison error estimates, varied depending upon stimulus complexity. Our results suggest that the number of items that can be stored is dependent on the complexity of the stimuli.

One of the earliest observable impairments in autism spectrum disorder (ASD) is a failure to orient to speech and other social stimuli. Auditory spatial attention, a key component of orienting to sounds in the environment, has been shown to be impaired in adults with ASD. Additionally, specific deficits in orienting to social sounds could be related to increased acoustic complexity of speech. We aimed to characterize auditory spatial attention in children with ASD and neurotypical controls, and to determine the effect of auditory stimulus complexity on spatial attention. In a spatial attention task, target and distractor sounds were played randomly in rapid succession from speakers in a free-field array. Participants attended to a central or peripheral location, and were instructed to respond to target sounds at the attended location while ignoring nearby sounds. Stimulus-specific blocks evaluated spatial attention for simple non-speech tones, speech sounds (vowels), and complex non-speech sounds matched to vowels on key acoustic properties. Children with ASD had significantly more diffuse auditory spatial attention than neurotypical children when attending front, indicated by increased responding to sounds at adjacent non-target locations. No significant differences in spatial attention emerged based on stimulus complexity. Additionally, in the ASD group, more diffuse spatial attention was associated with more severe ASD symptoms but not with general inattention symptoms. Spatial attention deficits have important implications for understanding social orienting deficits and atypical attentional processes that contribute to core deficits of ASD. Autism Res 2017, 10: 1405-1416. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Envelope following responses (EFRs) can be evoked by a wide range of auditory stimuli, but for many stimulus parameters the effect on EFR strength is not fully understood. This complicates the comparison of earlier studies and the design of new studies. Furthermore, the most optimal stimulus parameters are unknown. To help resolve this issue, we investigated the effects of four important stimulus parameters and their interactions on the EFR. Responses were measured in 16 normal hearing subjects evoked by stimuli with four levels of stimulus complexity (amplitude modulated noise, artificial vowels, natural vowels and vowel-consonant-vowel combinations), three fundamental frequencies (105 Hz, 185 Hz and 245 Hz), three fundamental frequency contours (upward sweeping, downward sweeping and flat) and three vowel identities (Flemish /a:/, /u:/, and /i:/). We found that EFRs evoked by artificial vowels were on average 4e6 dB SNR larger than responses evoked by the other stimulus complexities, probably because of (unnaturally) strong higher harmonics. Moreover, response amplitude decreased with fundamental frequency but response SNR remained largely unaffected. Thirdly, fundamental frequency variation within the stimulus did not impact EFR strength, but only when rate of change remained low (e.g. not the case for sweeping natural vowels). Finally, the vowel /i:/ appeared to evoke larger response amplitudes compared to /a:/ and /u:/, but analysis power was too small to confirm this statistically. Vowel- dependent differences in response strength have been suggested to stem from destructive interfer- ence between response components. We show how a model of the auditory periphery can simulate these interference patterns and predict response strength. Altogether, the results of this study can guide stimulus choice for future EFR research and practical applications ispartof: Hearing Research vol:393 ispartof: location:Netherlands status: published

Although the structure and function of the human visual system are determined in large part during early development, there is ample evidence for adult plasticity as well. Such plasticity has important consequences for restoring vision after cortical damage and for improving function in healthy people. Although these applications have shown promising results, they are often limited by pathological specificity: Improvements obtained through perceptual training fail to generalize beyond the trained stimulus feature or location. Efforts to reduce specificity have focused on the design of training tasks, but less is known about the effects of stimulus structure on the specificity of perceptual learning. Here, we leverage physiological findings from the dorsal visual pathway of the primate brain to explore the hypothesis that learning specificity is related to the complexity of the training stimulus. Specifically, because neurons in higher-level structures of the dorsal visual pathway exhibit little stimulus specificity, we reasoned that training with more complex stimuli would reduce the specificity of learning. We trained human observers on stimuli of varying complexity, ranging from simple sinewave gratings to complex optic flow fields. Our results show that training with more complex stimuli reduces specificity for spatial position and stimulus features. Such changes are associated with increased spatial integration. These findings were captured by a computational “reweighting” model that decoded the outputs of simulated neurons in areas MT and MST of the primate visual cortex. Our results suggest that the addition of more complex stimuli into perceptual learning paradigms provides a simple and effective way to minimize specificity in learning.

While stimulus complexity is known to affect the width of the temporal integration window (TIW), a quantitative evaluation of ecologically highly valid stimuli has not been conducted. We assumed that the degree of complexity is determined by the obviousness of the correspondence between the auditory onset and visual movement, and we evaluated the audiovisual complexity using video clips of a piano, a shakuhachi flute and human speech. In Experiment 1, a simultaneity judgment task was conducted using these three types of stimuli. The results showed that the width of TIW was wider for speech, compared with the shakuhachi and piano. Regression analysis revealed that the width of the TIW depended on the degree of complexity. In the second experiment, we investigated whether or not speech-specific factors affected the temporal integration. We used stimuli that either contained natural-speech sounds or white noise. The results revealed that the width of the TIW was wider for natural sentences, compared with white noise. Taken together, the width of the TIW might be affected by both the complexity and speech specificity.

Understanding how the human brain integrates information from the environment with ongoing, internal brain signals in order to produce individual perspective is an essential element of understanding the human mind. Brain signal complexity, measured with multiscale entropy, has been employed as a measure of information processing in the brain (Carpentier et al., 2016), and we propose that it can also be used to measure the information available from a stimulus. We can directly assess the correspondence, or functional isomorphism, between brain signal complexity and stimulus complexity as an indication of how well the brain reflects the content of the environment in an analysis that we termedcomplexity matching. Music makes an ideal stimulus input because it is a multidimensional, complex signal, and because of its emotion and reward-inducing potential. We found that electroencephalography (EEG) complexity was lower and more closely resembled the musical complexity when participants performed a perceptual task that required them to closely track the acoustics, compared to an emotional task that asked them to think about how the music made them feel. Music-derived reward scores on the Barcelona Music Reward Questionnaire (Mas-Herrero et al., 2013) correlated with worse complexity matching and higher EEG complexity. Compared to perceptual-level processing, emotional and reward responses are associated with additional internal information processes above and beyond those in the external stimulus.Significance StatementExperience of our world is combination of the input from the environment, our expectations, and individual responses. For example, the same piece of music can elict happiness in one person and sadness in another. We researched this by measuring the information in pieces of music and whether listener’s brain more closely followed that, or whether additional information was added by the brain. We noted when listener’s were reacting to how music made them feel, their brains added more information and the degree to which this occurred related to how much they find music rewarding. Thus, we were able to provide clues as to how the brain integrates incoming information, adding to it to provide a richer perceptual and emotional experience.

Two modes of internal representation, holistic and piecemeal transformation, have been reported as a means to perform mental rotation (MR) tasks. The stimulus complexity effect has been proposed as an indicator to disentangle between these two representation types. However, the complexity effect has not been fully confirmed owing to the fact that different performances could result from different types of stimuli. Moreover, whether the non-mirror foils play a role in forcing participants to encode all the information from the stimuli in MR tasks is still under debate. This study aims at testing the association between these two common types of representation with different stimuli in MR tasks. First, the numbers of segments and vertices in polygon stimuli were manipulated to test which property of the visual stimuli is more likely to influence the representation in MR tasks. Second, the role of non-mirror foils was examined by comparing the stimulus complexity effect in both with- and without-non-mirror foils conditions. The results revealed that the segment number affected the slope of the linear function relating response times to rotation angle, but the vertex number in the polygons did not. This suggests that a holistic representation was more likely to be adopted in processing integrated objects, whereas a piecemeal transformation was at play in processing multi-part objects. In addition, the stimulus complexity effect was observed in the with-non-mirror foils condition but not in the without-non-mirror foils one, providing a direct evidence to support the role of non-mirror foils in MR tasks.

Is there a fixed limit on how many objects we can hold actively in mind? Generally, researchers have found participants are worse at remembering a small number of objects if those objects are more complex, suggesting a limited resource rather than a fixed number of objects best explains working memory performance. However, some evidence has suggested that stimulus similarity better accounts for these effects and that, after accounting for such similarity, the data support a slot-based fixed item limit for working memory. Much of the evidence used to support the latter claim relies on working memory displays containing different categories of items. It has been found that, for large, across-category changes, performance does not differ for different kinds of complex stimuli. However, many of these studies fail to adequately control for the potential use of ensemble information in discriminating such large changes. Here, we sought to identify how much ensemble representations may explain performance across these tasks. In Experiment 1, we observed that, as set size increased from four to 12 items, capacity estimates for across-category changes increased linearly as well, providing evidence against the claim of a fixed capacity. In Experiment 2, we controlled for stimulus complexity and similarity but varied the utility of ensemble representations for the change-detection task. We observed significantly greater capacity when ensemble information could be used. Altogether, these results are contrary to a slot-like, fixed-object constraint on working memory capacity and consistent with object complexity and ensemble representations strongly affecting working memory performance.

Significance Whether the population activity in neuronal networks can be understood as the sum of individual activities or neurons jointly determine the state of populations is a fundamental question of neuroscience. Spike count correlations reflect coordination between pairs of neurons and therefore can be regarded as a signature of joint computations. So far, a majority of experimental and theoretical analyses considered these correlations noise and ignored stimulus-dependent aspects. Based on theoretical considerations, we argue that spike count correlations are stimulus dependent and variations in their structure can be predicted by stimulus content. Recording the activity of neurons from primary visual cortex in task-engaged monkeys, we confirm these predictions. These results provide insight into the computations performed by populations of cortical neurons., Spike count correlations (SCCs) are ubiquitous in sensory cortices, are characterized by rich structure, and arise from structured internal dynamics. However, most theories of visual perception treat contributions of neurons to the representation of stimuli independently and focus on mean responses. Here, we argue that, in a functional model of visual perception, featuring probabilistic inference over a hierarchy of features, inferences about high-level features modulate inferences about low-level features ultimately introducing structured internal dynamics and patterns in SCCs. Specifically, high-level inferences for complex stimuli establish the local context in which neurons in the primary visual cortex (V1) interpret stimuli. Since the local context differentially affects multiple neurons, this conjecture predicts specific modulations in the fine structure of SCCs as stimulus identity and, more importantly, stimulus complexity varies. We designed experiments with natural and synthetic stimuli to measure the fine structure of SCCs in V1 of awake behaving macaques and assessed their dependence on stimulus identity and stimulus statistics. We show that the fine structure of SCCs is specific to the identity of natural stimuli and changes in SCCs are independent of changes in response mean. Critically, we demonstrate that stimulus specificity of SCCs in V1 can be directly manipulated by altering the amount of high-order structure in synthetic stimuli. Finally, we show that simple phenomenological models of V1 activity cannot account for the observed SCC patterns and conclude that the stimulus dependence of SCCs is a natural consequence of structured internal dynamics in a hierarchical probabilistic model of natural images.

Contains fulltext : 202341.pdf (Publisher’s version ) (Open Access) Recently, we demonstrated complexity as a major factor for explaining individual differences in visual preferences for abstract digital art. We have shown that participants could best be separated into two groups based on their liking ratings for abstract digital art comprising geometric patterns: one group with a preference for complex visual patterns and another group with a preference for simple visual patterns. In the present study, building up on these results, we extended our investigations for complexity preferences from highly controlled visual stimuli to ecologically valid stimuli in the auditory modality. Similar to visual preferences, we showed that music preferences are highly influenced by stimulus complexity. We demonstrated this by clustering a large number of participants based on their liking ratings for song excerpts from various musical genres. Our results show that, based on their liking ratings, participants can best be separated into two groups: one group with a preference for more complex songs and another group with a preference for simpler songs. Finally, we considered various demographic and personal characteristics to explore differences between the groups, and reported that at least for the current data set age and gender to be significant factors separating the two groups. 11 p.