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This study investigated whether the interference between two tasks in dual-task processing stems from bottleneck limitations or insufficient cognitive resources due to resource sharing. Experiment 1 used tone discrimination as Task 1 and word or pseudoword classification as Task 2 to evaluate the effect of automatic versus controlled processing on dual-task interference under different SOA conditions. Experiment 2 reversed the task order. The results showed that dual-task interference persisted regardless of task type or order. Neither experiment found evidence that automatic tasks could eliminate interference. This suggests that resource limitations, rather than bottlenecks, may better explain dual-task costs. Specifically, when tasks compete for limited resources, the processing efficiency of both tasks is significantly reduced. Future research should explore how cognitive resources are dynamically allocated between tasks to better account for dual-task interference effects., (© 2024. The Psychonomic Society, Inc.)

It is well known that human information processing comprises several distinct subprocesses-namely, the perceptual, central, and motor stage. In each stage, attention plays an important role. Specifically, a type of attention-perceptual attention-operates to detect and identify a sensory input. Following this, another class of attention-central attention-is involved in working memory encoding and response selection at the central stage. While perceptual attention and central attention are known to be separate, distinct processes, some researchers reported findings that loading central attention postponed the deployment of perceptual attention needed to perform a spatial configuration search. We tested whether a similar pattern of results would emerge when a different kind of search task is used. To do so, we had participants perform a visual-search task of searching for a feature conjunction target, taxing perceptual attention while they are engaged in central processes, such as working memory encoding and response selection. The results showed that perceptual processing of conjunction search stimuli could be carried out concurrently with central processes. These results suggest that the nature of the concurrent visual search process is a determinant responsible for the dynamic relationship between perceptual attention deployed for visual search and central attention needed for working memory encoding and response selection.

Reading is a demanding task, constrained by inherent processing capacity limits. Do those capacity limits allow for multiple words to be recognized in parallel? In a recent study, we measured semantic categorization accuracy for nouns presented in pairs. The words were replaced by post-masks after an interval that was set to each subject's threshold, such that with focused attention they could categorize one word with ~80% accuracy. When subjects tried to divide attention between both words, their accuracy was so impaired that it supported a serial processing model: on each trial, subjects could categorize one word but had to guess about the other. In the experiments reported here, we investigated how our previous result generalizes across two tasks that require lexical access but vary in the depth of semantic processing (semantic categorization and lexical decision), and across different masking stimuli, word lengths, lexical frequencies and visual field positions. In all cases, the serial processing model was supported by two effects: (1) a sufficiently large accuracy deficit with divided compared to focused attention; and (2) a trial-by-trial stimulus processing tradeoff, meaning that the response to one word was more likely to be correct if the response to the other was incorrect. However, when the task was to detect colored letters, neither of those effects occurred, even though the post-masks limited accuracy in the same way. Altogether, the results are consistent with the hypothesis that visual processing of words is parallel but lexical access is serial.

Visual attention and response selection are processes that are limited by capacity. The present study focuses on whether visual attention is subject to the response selection bottleneck. This was investigated by conducting 2 dual-task experiments of the psychological refractory period (PRP) type. A visual conjunction search task was chosen as Task 2 in these experiments. Conjunction search requires the binding of the stimulus' defining features. This binding is performed in a serial search process in displays of different amounts of stimuli until the presence or absence of the target is correctly indicated. In Experiment 1, the conjunction search was combined with a 2-choice tone discrimination Task 1, and in Experiment 2 with a 2-choice color discrimination Task 1. Detailed reaction time (RT) analyses revealed concurrent performance of visual search to both tone and color in Task 1's response selection. In conclusion, visual attention is not subject to the response selection bottleneck.

Several studies of dual-task performance have demonstrated Task 2 to Task 1 response priming (backward compatibility effects), indicating some degree of parallel response computation for concurrent tasks and suggesting that the well-established response selection bottleneck (RSB) model may be incomplete. However, the RSB might be considered to remain informationally intact if this early parallel Task 2 response information does not persist across the attentional shift between tasks to contribute to overt Task 2 performance. We used an adapted psychological refractory period paradigm with an additional early transient Task 2 stimulus to examine whether response information generated for Task 2 in parallel with overt Task 1 response selection could persist across the bottleneck to influence eventual overt Task 2 performance. After controlling for potential indirect effects of Task 1 processing stage variability propagating onto Task 2 reaction time via locus of slack effects, we observed reliable and consistent effects of early Task 2 response information facilitating Task 2 reaction times. These effects were observed only when the responses to both tasks of the dual-task pair were compatible, under both univalent and bivalent response mappings across tasks. These findings may represent evidence of a variably sensitive response gating or suppression mechanism in dual-task performance and support the idea that backward response compatibility effects represent transient informational influences on central response codes, rather than later postbottleneck response execution processes.

When simultaneously performing two tasks that share response properties, interference can occur. Besides general performance decrements, performance in the first task is worse when the second task requires a spatially incompatible response, known as the backward crosstalk effect (BCE). The size of this BCE, similar to congruency effects in conflict tasks, is subject to a sequential modulation, with a smaller BCE after incompatible compared to compatible trials. In the present study, we focus on a potential bidirectional interaction between crosstalk (and its resolution) at a lower level of task performance and higher-order processes of task organization. Two questions were of particular interest: First, do participants switch task order more frequently after a conflict-prone incompatible trial than after a compatible trial? Second, does changing task order influence the efficiency of conflict resolution, as indexed by the size of the sequential modulation of the BCE. Across four experiments, we only found marginal evidence for an influence of lower-level conflict on higher-order processes of task organization, with only one experiment revealing a tendency to repeat task order following conflict. Our results thus suggest practical independence between conflict and task-order control. When separating processes of task selection and task performance, the sequential modulation was generally diminished, suggesting that conflict resolution in dual-tasks can be disrupted by a deliberate decision about task order, or, alternatively, by a longer inter-trial interval. Finally, the study found a strong bias towards repeating the same task order across trials, suggesting that task-order sets not only impact task performance but also guide task selection., (© 2024. The Author(s).)

The speed with which information from vision is transformed into working memory (WM) representations that resist interference from ongoing perception and cognition is the subject of conflicting results. Using distinct paradigms, researchers have arrived at estimates of the consolidation time course ranging from 25 ms to 1 s - a range of more than an order of magnitude. However, comparisons of consolidation duration across very different estimation paradigms rely on the implicit assumption that WM consolidation speed is a stable, structural constraint of the WM system. The extremely large variation in WM consolidation speed estimates across measurement approaches motivated the current work's goal of determining whether consolidation speed truly is a stable structural constraint of WM encoding, or instead might be under strategic control as suggested by some accounts. By manipulating the relative task priority of WM encoding and a subsequent sensorimotor decision in a dual-task paradigm, the current experiments demonstrate that the long duration of WM consolidation does not change as a result of task-specific strategies. These results allow comparison of WM consolidation across estimation approaches, are consistent with recent multi-phase WM consolidation models, and are consistent with consolidation duration being an inflexible structural limit., (© 2023. The Psychonomic Society, Inc.)

Four experiments investigated the extent to which a limited pool of resources can be shared between different tasks performed simultaneously when it is efficient to do so. The experiments used a prioritized processing paradigm, in which stimuli for both a primary task and a background task were presented in each trial. If the primary-task stimulus required a response in a trial, participants made only that response. If the primary-task stimulus did not require a response, participants responded to the background task. The main manipulation was the relative probability that a response would be required to the primary versus background task. In some blocks, the majority of trials required responses to the primary task (Experiments 1 and 2: 80%; Experiments 3 and 4: 60%), whereas in other blocks the majority required responses to the background task. Background-task responses were substantially faster in blocks where they were more likely to be required, consistent with the idea that more capacity was allocated to them in these blocks. Backward compatibility effects on primary-task responses and stimulus-onset asynchrony effects on background-task responses provided further evidence of greater capacity allocation to the background task when there was a higher probability of responding to it. The results support the view that two tasks can be processed in parallel, with resources divided between them, when it is efficient to do so.

Covert spatial attention allows us to prioritize processing at relevant locations. Perception is generally poorer when attention is distributed across multiple locations than when attention is focused on a single location. However, while divided attention typically impairs performance, recent work suggests that divided attention does not seem to impair detection of simple visual features. Here, we re-examined this possibility. In two experiments, observers detected a simple target (a vertical Gabor), and we manipulated whether attention was focused at one location (focal-cue condition) or distributed across two locations (distributed-cue condition). In Experiment 1, targets could appear independently at each location, such that observers needed to judge target presence for each location separately in the distributed-cue condition. Under these conditions, we found a robust cost of dividing attention. Next, we further probed what stage of processing gave rise to this cost. In Experiment 1, the cost of dividing attention could reflect a limit in the ability to make concurrent judgments about target presence. In Experiment 2, we simplified the task to test whether this was the case: just one target could appear on each trial, such that observers made a single judgment ("was a target present?") in both the focal-cue and distributed-cue conditions. Here, we found a marginal cost of dividing attention that was weaker than the cost in Experiment 1. Together, our results suggest that divided attention does impair detection of simple visual features, but that this cost is primarily due to a limit in post-perceptual processes., (© 2022. The Psychonomic Society, Inc.)

Mouse-tracking is regarded as a powerful technique to investigate latent cognitive and emotional states. However, drawing inferences from this manifold data source carries the risk of several pitfalls, especially when using aggregated data rather than single-trial trajectories. Researchers might reach wrong conclusions because averages lump together two distinct contributions that speak towards fundamentally different mechanisms underlying between-condition differences: influences from online-processing during action execution and influences from incomplete decision processes. Here, we propose a simple method to assess these factors, thus allowing us to probe whether process-pure interpretations are appropriate. By applying this method to data from 12 published experiments on ideomotor action control, we show that the interpretation of previous results changes when dissociating online processing from decision and initiation errors. Researchers using mouse-tracking to investigate cognition and emotion are therefore well advised to conduct detailed trial-by-trial analyses, particularly when they test for direct leakage of ongoing processing into movement trajectories., Competing Interests: Declarations. Conflicts of interest: The authors have no relevant financial or non-financial interests to disclose. Ethics approval, consent to participate, consent for publication: Based on the original authors’ publications., (© 2024. The Author(s).)

When a rhythm makes an event predictable, that event is perceived faster, and typically more accurately. However, the experiments showing this used simple tasks, and most manipulated temporal expectancy by using periodic or aperiodic precursors unrelated to stimulus and task. Three experiments tested the generality of these observations in a complex task in which rhythm was intrinsic to, rather than a precursor of, the information needed to respond: listeners averaged the laterality of a stream of noise bursts. We varied presentation rate, degree of periodicity, and average lateralisation. Decisions following a probe tone were fastest after periodic stimuli, and slowest after the most aperiodic stimuli. Without a probe tone, listeners responded sooner during periodic sequences, thus hearing less information. Periodicity did not benefit accuracy overall. This gain in speed but not accuracy for less information is not reported for simpler tasks. Neural entrainment supplemented by cognitive factors provide a tentative explanation. When the task is inherently complex and demands high attention over long durations, both expected-periodic and unexpected-aperiodic stimuli can increase response amplitude, enhancing stimulus representation, but periodicity increases confidence to respond early. Drift diffusion modelling supports this proposal: aperiodicity modulated the decision threshold, but not the drift rate or non-decision time. Together, these new data and the literature point towards task-dependent effects of temporal expectation on decision-making, showing interactions between rhythmic variance, task complexity, and sources of expectation about stimuli. We suggest the implications are worth exploring to extend understanding of rhythmicity on decision-making to everyday situations., (© 2024. The Psychonomic Society, Inc.)

Peripheral vision is limited due to several factors, such as visual resolution, crowding, and attention. When attention is not directed towards a stimulus, detection, discrimination, and identification are often compromised. Recent studies have found a new phenomenon that strongly limits peripheral vision, "redundancy masking". In redundancy masking, the number of perceived items in repeating patterns is reduced. For example, when presenting three lines in the peripheral visual field and asking participants to report the number of lines, often only two lines are reported. Here, we investigated what role attention plays in redundancy masking. If redundancy masking was due to limited attention to the target, it should be stronger when less attention is allocated to the target, and absent when attention is maximally focused on the target. Participants were presented with line arrays and reported the number of lines in three cueing conditions (i.e., single cue, double cue, and no cue). Redundancy masking was observed in all cueing conditions, with observers reporting fewer lines than presented in the single, double, and no cue conditions. These results suggest that redundancy masking is not due to limited attention. The number of lines reported was closer to the correct number of lines in the single compared to the double and the no cue conditions, suggesting that reduced attention additionally compromised stimulus discrimination, and replicating typical effects of diminished attention. Taken together, our results suggest that the extent of attention to peripherally presented stimuli modulates discrimination performance, but does not account for redundancy masking., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Psychonomic Society, Inc.)

The accurate perception of human crowds is integral to social understanding and interaction. Previous studies have shown that observers are sensitive to several crowd characteristics such as average facial expression, gender, identity, joint attention, and heading direction. In two experiments, we examined ensemble perception of crowd speed using standard point-light walkers (PLW). Participants were asked to estimate the average speed of a crowd consisting of 12 figures moving at different speeds. In Experiment 1, trials of intact PLWs alternated with trials of scrambled PLWs with a viewing duration of 3 seconds. We found that ensemble processing of crowd speed could rely on local motion alone, although a globally intact configuration enhanced performance. In Experiment 2, observers estimated the average speed of intact-PLW crowds that were displayed at reduced viewing durations across five blocks of trials (between 2500 ms and 500 ms). Estimation of fast crowds was precise and accurate regardless of viewing duration, and we estimated that three to four walkers could still be integrated at 500 ms. For slow crowds, we found a systematic deterioration in performance as viewing time reduced, and performance at 500 ms could not be distinguished from a single-walker response strategy. Overall, our results suggest that rapid and accurate ensemble perception of crowd speed is possible, although sensitive to the precise speed range examined.

The human visual system is very sensitive to the presence of faces in the environment, so much so that it can produce the perception of illusory faces in everyday objects. Growing research suggests that illusory faces and real faces are processed by similar perceptual and neural mechanisms, but whether this similarity extends to visual attention is less clear. A visual search study showed that illusory faces have a search advantage over objects when the types of objects vary to match the objects in the illusory faces (e.g., chair, pepper, clock) (Keys et al., 2021). Here, we examine whether the search advantage for illusory faces over objects remains when compared against objects that belong to a single category (flowers). In three experiments, we compared visual search of illusory faces, real faces, variable objects, and uniform objects (flowers). Search for real faces was best compared with all other types of targets. In contrast, search for illusory faces was only better than search for variable objects, not uniform objects. This result shows a limited visual search advantage for illusory faces and suggests that illusory faces may not be processed like real faces in visual attention., (© 2024. The Psychonomic Society, Inc.)

We investigated how sensitive visual processing is to spatiotemporal disruptions in ongoing visual events. Prior work has demonstrated that participants often miss spatiotemporal disruptions in videos presented in the form of scene edits or disruptions during saccades. Here, we asked whether this phenomenon generalizes to spatiotemporal disruptions that are not tied to saccades. In two flicker paradigm experiments, participants were instructed to identify spatiotemporal disruptions created when videos either jumped forward or backward in time. Participants often missed the jumps, and forward jumps were reported less frequently compared with backward jumps, demonstrating that a flicker paradigm produces effects similar to a saccade contingent disruption paradigm. These results suggest that difficulty detecting spatiotemporal disruptions is a general phenomenon that extends beyond trans-saccadic events., (© 2024. The Psychonomic Society, Inc.)

Target prevalence influences many cognitive processes during visual search, including target detection, search efficiency, and item processing. The present research investigated whether target prevalence may also impact the spread of attention during search. Relative to low-prevalence searches, high-prevalence searches typically yield higher fixation counts, particularly during target-absent trials. This may emerge because the attention spread around each fixation may be smaller for high than low prevalence searches. To test this, observers searched for targets within object arrays in Experiments 1 (free-viewing) and 2 (gaze-contingent viewing). In Experiment 3, observers searched for targets in a Rapid Serial Visual Presentation (RSVP) stream at the center of the display while simultaneously processing occasional peripheral objects. Experiment 1 used fixation patterns to estimate attentional spread, and revealed that attention was narrowed during high, relative to low, prevalence searches. This effect was weakened during gaze-contingent search (Experiment 2) but emerged again when eye movements were unnecessary in RSVP search (Experiment 3). These results suggest that, although task demands impact how attention is allocated across displays, attention may also narrow when searching for frequent targets., (© 2023. The Psychonomic Society, Inc.)

The congruency effect of a task-irrelevant distractor has been found to be modulated by task-relevant set size and display set size. The present study used a psychological refractory period (PRP) paradigm to examine the cognitive loci of the display set size effect (dilution effect) and the task-relevant set size effect (perceptual load effect) on distractor interference. A tone discrimination task (Task 1), in which a response was made to the pitch of the target tone, was followed by a letter discrimination task (Task 2) in which different types of visual target display were used. In Experiment 1, in which display set size was manipulated to examine the nature of the display set size effect on distractor interference in Task 2, the modulation of the congruency effect by display set size was observed at both short and long stimulus-onset asynchronies (SOAs), indicating that the display set size effect occurred after the target was selected for processing in the focused attention stage. In Experiment 2, in which task-relevant set size was manipulated to examine the nature of the task-relevant set size effect on distractor interference in Task 2, the effects of task-relevant set size increased with SOA, suggesting that the target selection efficiency in the preattentive stage was impaired with increasing task-relevant set size. These results suggest that display set size and task-relevant set size modulate distractor processing in different ways.

The stop-signal task (SST) is widely used for studying the speed of the latent process of response inhibition. The SST patterns are typically explained by a horse-race model (HRM) with supposed Go and Stop processes. However, HRM does not agree with the sequential-stage model of response control. As a result, the exact relationship between the response selection, the response execution stages, and the Stop process remains unclear. We propose that response selection occurs within the stop-signal delay (SSD) period, and that the competition between the Go and Stop processes occurs within the response execution period. To confirm this, we conducted two experiments. In Experiment 1, participants carried out a modified SST task with an additional stimulus category - Cued-Go. In the Cued-Go trials, cues were followed by imperative Go signals. The Cue-Go period duration was dynamically adjusted by an adaptive algorithm based on the response times reflecting the individual response selection duration. In Experiment 2, Cued-Go stimuli were followed by Stop Signals in half of the trials and response inhibition efficiency was calculated. The results of Experiment 1 indicate that SSD reflects the duration of the response selection process. The results of Experiment 2 show that this process has an independent and small effect on the effectiveness of controlled inhibition of the target response. Based on our findings, we propose a two-stage model of response inhibition in SST, with the first stage including response selection process and the second stage response inhibition following the SS presentation., (© 2023. The Psychonomic Society, Inc.)

While holding items in working memory has been shown to improve delayed long-term recall, the mechanisms underlying this relationship remain unclear. One potential mechanism is working memory consolidation, which may facilitate the formation of novel associations between items during learning and lead to improved memory search at delayed retrieval. Forming novel associations via consolidation may share mechanisms with creative ability. The present research aims to explore how an individual's creativity relates to the relationship between working memory consolidation and long-term memory. In Experiment 1, participants completed a stimulus identification task that manipulated the need for consolidation followed by a surprise delayed recognition task and measures of objective and self-reported creativity. While creativity scores were correlated with general performance on memory tasks, this effect was not related to working memory consolidation. In Experiment 2, participants were induced into either a creative or a non-creative state prior to completing the stimulus identification and delayed recognition tasks. Performance on these tasks was not significantly different between the groups and was again unrelated to working memory consolidation. The results of these two experiments suggest that creativity is not related to the mechanism underlying the effect of working memory consolidation on delayed recognition., (© 2022. The Psychonomic Society, Inc.)

Human perception of time is far from accurate and is subject to distortions. Previous research has demonstrated that any manipulation that distorts the perceived velocity of visible moving objects may shift prediction motion (PM) performance during occlusion. However, it is not clear whether motor action has the same influence during occlusion in the PM task. This work evaluated the influence of action on PM performance in two experiments. In both cases, participants performed an interruption paradigm, evaluating if an occluded object had reappeared earlier or later than expected. This task was done simultaneously with a motor action. In Experiment 1, we compared the PM performance according to the timing of the action made while the object was still visible or occluded. In Experiment 2, participants had to perform (or not) a motor action if the target was green (or red). In both experiments, our results showed that the duration of the object's occlusion was underestimated in the specific case of acting during the occlusion period. These results suggest that action and temporal perception share similar neural bases. Future research is needed to confirm this hypothesis., (© 2023. The Psychonomic Society, Inc.)

Individuals often need to make quick decisions based on incomplete or "noisy" information. This requires the coordination of attentional, perceptual, cognitive, and behavioral mechanisms. This poses a challenge for isolating the unique effects of each subprocess from behavioral data, which reflect the summation of all subprocesses combined. Sequential sampling models offer a more detailed examination of behavioral data, enabling us to separate decisional and non-decisional processes at play in a task. Participants were required to identify briefly presented shapes while perceptual (duration, size, location) and response features (location-congruent/-incongruent/-neutral) of the task were manipulated. The diffusion model (Ratcliff, 1978) was used to dissociate decisional and executive processes in the task. In Experiment 1, stimuli were presented for either 20 or 80 ms to the left or right of a central fixation while response keys were positioned horizontally. In Experiment 2, stimulus size was manipulated rather than duration. In Experiment 3, response keys were positioned vertically. Results showed a duration x response mapping interaction. Participants displayed stimulus-response (S-R) congruency biases only on short-duration trials. This effect was observed for both horizontal and vertical response key mappings. Stimulus size affected participant response speed, but did not elicit S-R congruency biases. The present findings show that when perceptual quality of evidence is poor, individuals rely more heavily on spatial-motor mechanisms when making speeded choice decisions. Furthermore, positioning response keys vertically is insufficient to eliminate S-R congruency effects. Diffusion model parameters are presented and implications of the model are discussed., (© 2023. The Psychonomic Society, Inc.)

In the present study, we tested the applicability of the computational model of the illusion of interrupted spatial extent (Bulatov, Marma, & Bulatova, Attention, Perception, & Psychophysics, 82, 2714-2727, 2020) to account for the psychophysical data collected with three-dot stimuli containing a cross-shaped contextual distractor. In different series of experiments, the illusion magnitude changes caused by the rotation of distractors with different values of the internal angle (45°, 75°, and 90°) were quantitatively determined. It was shown that the data obtained for all modifications of stimuli can be rather well approximated by model functions proportional to the sum of the absolute values of cosines. A good agreement between theoretical calculations and experimental results supports the suggestion that the perceptual displacement of the stimulus terminators, which occurs due to the processes of local integration of neural activity, may be one of the main causes of the illusion investigated., (© 2022. The Psychonomic Society, Inc.)

Cognitive decrements are typical of physiological aging. Among these age-related cognitive changes, visuo-spatial working memory (vWM) decline has a prominent role due to its effects on other cognitive functions and daily routines. To reinforce vWM in the aging population, several cognitive training interventions have been developed in the past years. Given that vWM functioning depends (at least partially) on the efficiency of attention selection of the relevant objects, in the present study we implemented a short (five sessions), online intervention that primarily trained attentive individuation of target items and tested training effects on a vWM task. Attention training effects were compared with practice (i.e., a group that repeatedly performed the same vWM task) and test-retest effects (i.e., a passive group). After the training, the results showed attention training effects of the same magnitude as practice effects, confirming that the enhancement of attentive individuation has a positive cascade influence on maintaining items in vWM. Moreover, training and practice effects were only evident in low-performing older adults. Thus, interindividual differences at baseline crucially contribute to training outcomes and are a fundamental factor to be accounted for in the implementation of cognitive training protocols., (© 2022. The Psychonomic Society, Inc.)

Usually people can estimate the correct position of a moving object even when it temporarily moves behind an occlusion. Studies have been performed on this type of occluded motion with prediction motion (PM) tasks in the laboratory. Previous publications have emphasized that people could use mental imagery or apply an oculomotor system to estimate the arrival of a moving stimulus at the target place. Nevertheless, these two ways cannot account for the performance difference under a different set of conditions. Our study tested the role of time structure in a time-to-collision (TTC) task using visual and auditory modalities. In the visual condition, the moving red bar travelled from left to right and was invisible during the entire course but flashed at the initial and the occluded points. The auditory condition and visual condition were alike, except that the flashes in the visual condition were changed to clicks at the initial and the occluded points. The results illustrated that participants' performance was better in the equal time structure condition. The comparison between the two sense modalities demonstrated a similar tendency, which suggested there could be common cognitive processes between visual and auditory modalities when participants took advantage of temporal cues to judge TTC., (© 2021. The Psychonomic Society, Inc.)

Recently, paradigms in the face recognition literature have been adopted to reveal holistic processing in word recognition. It is unknown, however, whether different measures of holistic word processing share similar underlying mechanisms, and whether fluent word reading relies on holistic word processing. We measured holistic processing effects in three paradigms (composite, configural sensitivity, part-whole) as well as in reading fluency (3DM task: reading aloud high- and low-frequency words and pseudowords). Bin scores were used to combine accuracy and response time variables in the quest for a more comprehensive, reliable, and valid measure of holistic processing. Weak correlations were found between the different holistic processing measures, with only a significant correlation between the configural sensitivity effect and part-whole effect (r = .32) and a trend of a positive correlation between the word composite effect and configural sensitivity effect (r = .21). Of the three holistic processing measures, only one (part-whole effect) correlated with a lexical access measure of 3DM (r = .23). We also performed a principal component analysis (PCA) of performance in the three lists of 3DM, with the second most probably reflecting lexical access processes. There was a tendency for a positive correlation between part-whole bin measure and Component 2 of PCA. We also found a positive correlation between composite aligned in accuracy and Component 2 of PCA.Our results show that different measures of holistic word processing reflect predominantly different mechanisms, and that differences among normal readers in word reading do not seem to depend highly on holistic processing., (© 2022. The Psychonomic Society, Inc.)

To successfully interact with objects in complex and crowded environments, we often perform visual search to detect or identify a relevant target (or targets) among distractors. Previous studies have reported a redundancy gain when two targets instead of one are presented in a simple target detection task. However, research is scant about the role of multiple targets in target discrimination tasks, especially in the context of visual search. Here, we address this question and investigate its underlying mechanisms in a pop-out search paradigm. In Experiment 1, we directly compared visual search performance for one or two targets for detection or discrimination tasks. We found that two targets led to a redundancy gain for detection, whereas it led to a redundancy cost for discrimination. To understand the basis for the redundancy cost observed in discrimination tasks for multiple targets, we further investigated the role of perceptual grouping (Experiment 2) and stimulus-response feature compatibility (Experiment 3). We determined that the strength of perceptual grouping among homogenous distractors was attenuated when two targets were present compared with one. We also found that response compatibility between two targets contributed more to the redundancy cost compared with perceptual compatibility. Taken together, our results show how pop-out search involving two targets is modulated by the level of feature processing, perceptual grouping, and compatibility of perceptual and response features., (© 2022. The Psychonomic Society, Inc.)

Recently a theory (Zhaoping, Vision Research, 136, 32-49, 2017) proposed that top-down feedback from higher to lower visual cortical areas, to aid visual recognition, is stronger in the central than in the peripheral visual fields. Since top-down feedback helps feature binding, a critical visual recognition process, this theory predicts that insufficient feedback in the periphery should make feature misbinding more likely. To test this prediction, this study assessed binding between color and motion features, or between luminance and motion features, at different visual field eccentricities. We first used color-motion stimuli containing equiluminant red and green dots moving in opposite directions, for example, red dots moved leftward while green dots moved rightward. Such stimuli were shown in both a central reference strip and a peripheral test strip; participants reported whether it was the first or second interval in a trial in which the dots of each color moved in the opposite directions between the two strips. The center of the test strip was at 4° or 15° away from the gaze fixation. Participants' performance was much worse when the test strip was more peripheral, suggesting that feature misbinding occurred more frequently there. This held even when the size and density of the dots were adjusted by eccentricity-dependent cortical magnification factors, and even when red/green dots were replaced by yellow/blue dots or black/white dots to suit the retinal input sampling peripherally. Our findings support that top-down feedback is more directed to central vision, which can resolve ambiguities in feature binding at more central visual locations., (© 2022. The Psychonomic Society, Inc.)

The present study investigated whether the asymmetry in magnitude between the wings-in and wings-out versions of the Müller-Lyer illusion can be explained by the manifestation of accompanying effects of the filled-space illusion. In psychophysical experiments, the three-dot stimuli were used, and in different series, a single set of the Müller-Lyer wings was attached to the left or to right terminating dot. To check whether the summation of illusory effects occurs, experiments with two sets of the wings forming the Judd figure were performed. To evaluate the standalone manifestation of the filled-space illusion, we conducted experiments with distracting cross (two sets of coinciding and oppositely oriented wings) centered on the lateral terminator of the stimulus. To interpret the experimental data, we used computational procedures of previously developed quantitative models of hypothetical visual mechanisms underlying the emergence of the Müller-Lyer illusion and the filled-space illusion. It was demonstrated that theoretical calculations adequately account for the illusion magnitude variations for all modifications of stimuli, which convincingly supports the suggestion that the concomitant manifestation of the filled-space illusion is powerful enough to be considered as one of the main reasons for the asymmetric properties of illusions of extent of the Müller-Lyer type., (© 2021. The Psychonomic Society, Inc.)

Previous research on emotional bias in face perception has shown inconsistent findings, proposing either angry or happy faces to be detected more efficiently. A recent study showed that the anger superiority effect (ASE), which showed in the high attentional demand condition, vanished in the low attentional demand condition. The authors thus proposed an attentional demands modulation hypothesis to interpret the inconsistent findings. The present study tested this hypothesis in a visual crowding task in which participants were instructed to determine whether the target face was happy or angry. Attentional demands were manipulated by changing the strength of crowding, including presenting stimuli in different configurations (Experiment 1), and setting different target-flanker separations and presenting stimuli in different eccentricities (Experiment 2). Experiment 1 showed an ASE when the stimulus configuration incurred a high attentional demand. Intriguingly, the ASE became weaker and then disappeared as the attentional demand became lower. Experiment 2 replicated this finding and showed that the ASE decreased as the target-flanker separation became larger. Together, these results suggest that the emergence and magnitude of ASE is modulated by attentional demands, which supports the attentional demands modulation hypothesis., (© 2021. The Psychonomic Society, Inc.)

Data compression in memory is a cognitive process allowing participants to cope with complexity to reduce information load. However, previous studies have not yet considered the hypothesis that this process could also lead to over-simplifying information due to haphazard amplification of the compression process itself. For instance, we could expect that the over-regularized features of a visual scene could produce false recognition of patterns, not because of storage capacity limits but because of an errant compression process. To prompt memory compression in our participants, we used multielement visual displays for which the underlying information varied in compressibility. The compressibility of our material could vary depending on the number of common features between the multi-dimensional objects in the displays. We measured both accuracy and response times by probing memory representations with probes that we hypothesized could modify the participants' representations. We confirm that more compressible information facilitates performance, but a more novel finding is that compression can produce both typical memory errors and lengthened response times. Our findings provide clearer evidence of the forms of compression that participants carry out., (© 2021. The Psychonomic Society, Inc.)

The distance effect is the change in the performance during numerical magnitude comparison, depending on the numerical distance between the compared numbers (Moyer & Landauer, Nature, 215[5109], 1519-1520, 1967). This effect is generally accepted as evidence for the mental number line (MNL) hypothesis, which proposes that the mental representation of the numbers align in an increasing linear (or monotone) order. The majority of studies investigating the distance effect are focused on the reaction time (RT) findings, which show slower responses for closer numbers. In the present study, we examined the distance effect by applying signal detection theory (SDT) to a magnitude comparison task. We aimed to reveal whether discrimination ability and the response bias measures were affected by the location of numbers on the MNL. To accomplish this, we developed a magnitude comparison task using a go/no-go procedure in which participants performed a magnitude comparison based on a reference number (i.e., 5). Results revealed a substantial distance effect in both sensitivity and response bias measures-a better discrimination performance for far numbers, and a larger response bias for close numbers. In addition, an RT distribution analysis revealed that the distance effect seems to originate mainly from slower responses. Based on the current data, we suggest that sensitivity and response bias measures could offer comprehensive information in the understanding of number-based decisions.

The occupancy model (OM) was proposed to explain how the spatial arrangement of dots in sparse random patterns affects their perceived numerosity. The model's central thesis maintained that each dot seemingly fills or occupies its surrounding area within a fixed radius r o and the total area collectively occupied by all the dots determines their apparent number. Because the perceptual system is not adapted for the precise estimation of area, it looks likely that the OM is just a convenient computational algorithm that does not necessarily correspond to the processes that actually take place in the perceptual system. As an alternative, the proximity model (PM) was proposed, which instead relies on a binomial function with the probability β characterizing the perceptual salience with which each element can be registered by the perceptual system. It was also assumed that the magnitude of β is proportional to the distance between a dot and its nearest neighbor. A simulation experiment demonstrated that the occupancy area computed according to the OM can almost perfectly be replicated by the mean nearest neighbor distance. It was concluded that proximity between elements is a critical factor in determining their perceived numerosity, but the exact algorithm that is used for the measure of proximities is yet to be established.

Multiple-object tracking (MOT) involves keeping track of the positions of multiple independent target items as they move among distractors. According to Pylyshyn (Cognition, 80, 127-158, 2001), the item individuation mechanism used in MOT is also used in visually guided touch. To test this, we compared single-task MOT (MOT alone) with dual-task MOT (MOT while touching items that changed colour), looking for interference: cases where single-task performance was worse than dual-task. Touching items that changed colour interfered with MOT, but effects varied depending on whether the item touched was a target or distractor in MOT. Touching distractors always reduced MOT performance more than touching targets. Touching targets during MOT did not interfere when there was only a single target to track but interfered more once there were two or more targets. We also measured interference based on latencies to touch items that changed colour, comparing single and dual-task conditions (touch alone, touch + track). MOT interfered with touch, increasing RT to touch items that changed colour, with latencies significantly higher when those items were distractors rather than targets. Overall, there was general interference (differences between single and dual-task performance), as might be expected if coordinating the two tasks required a common limited resource such as general attention or working memory. However, there was also differential interference that varied based on whether the touched item was a target or distractor in MOT. This differential interference suggests the specific mechanisms used in MOT may also play a role in visually guided touch.

The natural environment is full of redundant information that the visual system compresses into an ensemble representation by averaging features of groups of items. Ensemble perception has been shown to operate with remarkable flexibility, efficiently integrating information across a variety of visual domains. In the current set of experiments, we tested whether average size representations reflect the physical size of objects displayed on a screen or perceptual transformations due to size constancy. We induced a perceptual change by presenting sets of triangles with linear perspective cues - lines converging at the horizon. Assuming a constant size, these cues cause individual objects "in the distance" to appear larger than objects without distance cues, due to size constancy heuristics. Observers viewed sets of triangles with and without linear perspective cues and judged whether a subsequently presented test triangle was larger or smaller than the average size of the preceding set. Results revealed ensemble size representations took size constancy into account, reflecting the perceived size of the triangles rather than their absolute size. Interestingly, the amount of bias exhibited was well characterized by the summed bias associated with each of the three triangles presented individually. Other pictorial cues to depth, such as occlusion and height-in-field, did not elicit the same bias when those were the only depth cues available. Overall, our results complement and extend other work showing that average size reflects the perceptual size of individual items in a set.

Through ensemble encoding, the visual system compresses redundant statistical properties from multiple items into a single summary metric (e.g., average size). Numerous studies have shown that global summary information is extracted quickly, does not require access to single-item representations, and often interferes with reports of single items from the set. Yet a thorough understanding of ensemble processing would benefit from a more extensive investigation at the local level. Thus, the purpose of this study was to provide a more critical inspection of global-local processing in ensemble perception. Taking inspiration from Navon (Cognitive Psychology, 9(3), 353-383, 1977), we employed a novel paradigm that independently manipulates the degree of interference at the global (mean) or local (single item) level of the ensemble. Initial results were consistent with reciprocal interference between global and local ensemble processing. However, further testing revealed that local interference effects were better explained by interference from another summary statistic, the range of the set. Furthermore, participants were unable to disambiguate single items from the ensemble display from other items that were within the ensemble range but, critically, were not actually present in the ensemble. Thus, it appears that local item values are likely inferred based on their relationship to higher-order summary statistics such as the range and the mean. These results conflict with claims that local information is captured alongside global information in summary representations. In such studies, successful identification of set members was not compared with misidentification of items within the range, but which were nevertheless not presented within the set.

Ensemble statistics of a visual scene can be estimated to provide a gist of the scene without detailed analysis of all individual items. The simplest and most widely studied ensemble statistic is mean estimation, which requires averaging an ensemble of elements. Averaging is useful to estimate the mean of an ensemble and discard the variance. The source of variance can be external (i.e., variance across the physical elements) or internal (i.e., imprecisions in the estimates of the elements by the visual system). The equivalent noise paradigm is often used to measure the impact of the internal variance (i.e., the equivalent input noise). This paradigm relies on the assumption that the averaging process is equally effective independently of the main source of variance, internal or external, so any difference between the processing when the main source of variance is internal or external must be assumed not to affect the averaging efficiency. The current fMRI study compared the neural activity when the main variance is caused by the stimulus (i.e., high variance) and when it is caused by imprecisions in the estimates of the elements by the visual system (i.e., low variance). The results showed that the right superior frontal and left middle frontal gyri can be significantly more activated when the variance in the orientation of the Gabors was high than when it was low. Consequently, the use of the equivalent noise paradigm requires the assumption that such additional neural activity in high variance does not affect the averaging efficiency.

Most visual scenes contain information at different spatial scales, including the local and global, or the detail and gist. Global processes have become increasingly implicated in research examining summary statistical perception, initially as the output of ensemble coding, and more recently as a gating mechanism for selecting which information is included in the averaging process itself. Yet local and global processing are known to be rapidly integrated by the visual system, and it is plausible that global-level information, like spatial organization, may be included as an input during ensemble coding. We tested this hypothesis using an ensemble shape-perception task in which observers evaluated the mean aspect ratios of sets of ellipses. In addition to varying the aspect ratios of the individual shapes, we independently varied the spatial arrangements of the sets so that they had either flat or tall organizations at the global level. We found that observers made precise summary judgments about the average aspect ratios of the sets by integrating information from multiple shapes. More importantly, global flat and tall organizations were incorporated into ensemble judgments about the sets; summary judgments were biased in the directions of the global spatial arrangements on each trial. This global-to-local integration even occurred when the global organizations were masked. Our results demonstrate that the process of summary representation can include information from both the local and global scales. The gist is not just an output of ensemble representation - it can be included as an input to the mechanism itself.

Ensemble statistics are often thought of as a reliable impression of numerous items despite limited capacities to consciously represent each individual. However, whether all items equally contribute to ensemble summaries (e.g., mean) and whether they might be affected by known limited-capacity processes, such as focused attention, is still debated. We addressed these questions via a recently described "amplification effect," a systematic bias of perceived mean (e.g., average size) towards the more salient "tail" of a feature distribution (e.g., larger items). In our experiments, observers adjusted the mean orientation of sets of items varying in set size. We made some of the items more salient or less salient by changing their size. While the whole orientation distribution was fixed, the more salient subset could be shifted relative to the set mean or differ in range. We measured the bias away from the set mean and the standard deviation (SD) of errors, as it is known to reflect the physical range from which ensemble information is sampled. We found that bias and SD changes followed the shifts and range changes in salient subsets, providing evidence for amplification. However, these changes were weaker than those expected from sampling only salient items, suggesting that less salient items were also sampled. Importantly, the SD decreased as a function of set size, which is only possible if the number of sampled elements increased with set size. Overall, we conclude that orientation summary statistics are sampled from an entire ensemble and modulated by the amplification effect of attention.

Early in his career C.W. Eriksen published in Psychological Review what turned out to be a highly impactful critique on methods and findings on the topic of unconscious influences on discrimination and awareness. His incisive commentary on extant methodology employed at that time - especially the heavy dependence on subjective reports - clearly was heard by others moving forward, as evidenced by the subsequent, lively discussions within the literature concerning the very definition of the notion of unconscious processing. Of equal importance, Eriksen's paper provided an impetus for the development of more refined techniques for manipulating perceptual awareness and for measuring the consequences of those manipulations. My purpose in this essay is to ensure that Eriksen's seminal contributions concerning unconscious phenomena remain within the awareness of the many current investigators working on this popular topic.

Timing can be processed explicitly or implicitly. Temporal orienting is a typical implicit timing through which we can anticipate and prepare an optimized response to forthcoming events. It is, however, not yet clear whether mechanisms such as temporal-pulse accumulation and attentional gating (more attention, more accumulated temporal pulses) underly the internal representations of temporal orienting, as in explicit timing. To clarify this, a dual-task paradigm, consisting of a temporal orienting and an interference task, was adopted. Consistent with the temporal-pulse-accumulation and attentional-gating model, reaction times to the target detection of temporal orienting increased as the interference stimuli were temporally closer to the target, i.e., a location effect for temporal orienting. This effect is likely due to attention being diverted away from temporal orienting to monitor the occurrence of the interference stimuli for a longer time, resulting in greater temporal pulse loss and less accurate temporal orienting for conditions with later interference stimuli. The temporal-pulse-accumulation aspect in temporal orienting received further support by taking an explicit duration reproduction (containing a second temporal-pulse accumulation) as the interference task. On the one hand, temporal orienting became less accurate with increased temporal-pulse-accumulation overlaps between the dual tasks; on the other hand, two-way (one for temporal orienting and the other for duration reproduction), rather than one-way, location effects were observed, implying processing conflicts between the two temporal-pulse accumulations. Taken together, these results suggest that implicit and explicit timing may share common mechanisms upon internal temporal representations.

A core assumption of ideomotor theory is that learned bidirectional associations between actions and their effects enable agents to select and initiate actions by anticipating their sensory consequences. Although the acquisition of bidirectional action-effect (A-E) associations built on the experience of one's own movements has received considerable empirical support, the available evidence for A-E learning through the observation of others' actions and their effects remains limited. In two experiments, we tested whether A-E associations could be acquired through social learning in an experimental setup involving observation of virtual actions. In an acquisition phase, participants repeatedly observed finger movements on a screen, and each movement was consistently followed by a specific effect tone. In the subsequent test phase, tones were presented as imperative stimuli in a reaction-time task. In both experiments, reaction times were shorter when tones required the same response with which they had been linked in the preceding observation phase, compared with when they required a different response, revealing the impact of A-E associations acquired through observation. Similar results were obtained whether the movements observed during the acquisition phase were spatially aligned (Experiment 1) or not (Experiment 2) with participants' responses in the test phase, ruling out the possibility that the results merely reflect spatial compatibility effects. Our findings add new evidence for an acquisition of A-E associations through observation. Importantly, we generalize this acquisition process to the observation of virtual actions. These findings further confirm effect-based action control, as proposed by ideomotor theory.

People's parallel-processing ability is limited, as demonstrated by the psychological refractory period (PRP) effect: The reaction time to the second stimulus (RT2) increases as the stimulus onset asynchrony (SOA) between two stimuli decreases. Most theoretical models of PRP are independent of modalities. Previous research on PRP mainly focused on vision and audition as input modalities; tactile stimuli have not been fully explored. Research using other paradigms and involving tactile stimuli, however, found that dual-task performance depended on input modalities. This study explored PRP with all the combinations of input modalities. Thirty participants judged the magnitude (small or large) of two stimuli presented in different modalities with an SOA of 75-1,200 ms. PRP effect was observed, i.e., RT2 increased with a decreasing SOA, in all the modalities. Only in the auditory-tactile condition did the accuracy of Task 2 decrease with a decreasing SOA. In the auditory-tactile and tactile-visual conditions, RT to the first stimulus also increased with a decreasing SOA. Current models could only explain part of the results, and modality characteristics help to explain the overall data pattern better. Limitations and directions for future studies regarding reaction time, task difficulty, and response modalities are discussed.

When two overlapping tasks are processed, they hit a bottleneck at a central processing stage that prevents simultaneous processing of the two tasks. Thus far, however, the factors determining the processing order of the tasks at the bottleneck are unknown. The present study was designed to (re)investigate whether the arrival times of the two tasks at the central bottleneck are a key determinant of the processing order (cf. Sigman & Dehaene, 2006). To this end, we implemented a visual-auditory dual task with a random stimulus order, in which we manipulated arrival time by prolonging the initial, perceptual processing stage (stimulus analysis) of the visual task and compared the effects of this manipulation with those of one impacting the central bottleneck stage of the visual task. Additionally, we implemented two instruction conditions: Participants were told to respond either in the order of stimulus presentation or in the order they preferred. The manipulation of the visual perception stage led to an increase in task response reversals (i.e., the response order was different from the order of stimulus presentation), whereas there was no such increase when the bottleneck stage was manipulated. This pattern provides conclusive evidence that the processing order at the bottleneck is (at least in part) determined by the arrival times of the tasks at that point. Reaction time differences between the two instruction conditions indicated that additional control processes are engaged in determining task processing order when the participants are expressly told to respond in the order of stimulus presentation.

Recent results from our laboratory showed that, in fixed-target parallel search tasks, reaction times increase in a logarithmic fashion with set size, and the slope of this logarithmic function is modulated by lure-target similarity. These results were interpreted as being consistent with a processing architecture where early vision (stage one) processes elements in the display in exhaustive fashion with unlimited capacity and with a limitation in resolution. Here, we evaluate the contribution of crowding to our recent logarithmic search slope findings, considering the possibility that peripheral pooling of features (as observed in crowding) may be responsible for logarithmic efficiency. Factors known to affect the strength of crowding were varied, specifically: item spacing and similarity. The results from three experiments converge on the same pattern of results: reaction times increased logarithmically with set size and were modulated by lure-target similarity even when crowding was minimized within displays through an inter-item spacing manipulation. Furthermore, we found logarithmic search efficiencies were overall improved in displays where crowding was minimized compared to displays where crowding was possible. The findings from these three experiments suggest logarithmic efficiency in efficient search is not the result peripheral pooling of features. That said, the presence of crowding does tend to reduce search efficiency, even in "pop-out" search situations.

To keep track of dynamically changing objects in one's environment, it is necessary to individuate them from other objects, both temporally and spatially. Spatially, objects can be selected from nearby distractors using selective attention. Temporally, object updating processes incorporate new information into existing representations over time. Both of these processes have been implicated in a type of visual masking called object-substitution masking (OSM). Previous studies have found that the number of distractors (impacting selective attention) interacts with the strength of OSM. However, it has been suggested that this interaction is an artifact of ceiling performance at low set sizes, rather than necessitating a failure of attention during masking. Using event-related potentials (ERPs), we examined whether set size and masking interact as measured by markers of selective attention (N2pc) and visual working memory consolidation/maintenance (SPCN). Set size was found to affect the N2pc (200-350 ms) and late SPCN (500-650 ms), reflecting increased demands on selective attention and unnecessary storage respectively. An early window of the SPCN (350-500 ms) was affected by masking, suggesting that OSM influences object consolidation processes in this window, independent of the number of distractors. Overall, it was found that selective attention and visual awareness are dissociable neural processes in OSM, and that they are independently affected by set size and masking manipulations. Moreover, we found that the early SPCN may reflect disruptions to object consolidation, potentially revealing a neural mechanism supporting an object individuation-through-updating account of OSM.

In many dual-task situations, responses to the second of two tasks are slowed when the time between tasks is short. The response-selection bottleneck model of dual-task performance accounts for this phenomenon by assuming that central processing of the second task is blocked by a bottleneck until central processing of Task 1 is complete. This assumption could be called into question if it could be demonstrated that the response to Task 2 affected the central processing of Task 1, a backward response compatibility effect. Such effects are well-established in younger adults. Backward compatibility effects in older (as well as younger) adults were explored in two experiments. The first experiment found clear backward response compatibility effects for younger adults but no evidence of them for older adults. The second experiment explored backward stimulus compatibility and found similar effects in both younger and older adults. Evidence possibly consistent with some pre-bottleneck processing of Task 2 central stages also was found in the second experiment in both age groups. For younger adults, the results provide further evidence falsifying the claim of an immutable response selection bottleneck. For older adults, the evidence suggested that Task 2 affects Task 1 when there is stimulus compatibility but not when there is response compatibility.

When reading, the visual system is confronted with many words simultaneously. How much of that information can a reader process at once? Previous studies demonstrated that low-level visual features of multiple words are processed in parallel, but lexical attributes are processed serially, for one word at a time. This implies that an internal bottleneck lies somewhere between early visual and lexical analysis. We used a dual-task behavioral paradigm to investigate whether this bottleneck lies at the stage of letter recognition or phonological decoding. On each trial, two letter strings were flashed briefly, one above and one below fixation, and then masked. In the letter identification experiment, participants indicated whether a vowel was present in a particular letter string. In the phonological decoding experiment, participants indicated whether the letter string was pronounceable. We compared accuracy in a focused attention condition, in which participants judged only one of the two strings, with accuracy in a divided attention condition, in which participants judged both strings independently. In both experiments, the cost of dividing attention was so large that it supported a serial model: participants were able to process only one letter string per trial. Furthermore, we found a stimulus processing trade-off that is characteristic of serial processing: When participants judged one string correctly, they were less likely to judge the other string correctly. Therefore, the bottleneck that constrains word recognition under these conditions arises at a sub-lexical level, perhaps due to a limit on the efficiency of letter recognition., (© 2024. The Author(s).)

Executive function, or cognitive control, describes the ability to guide information processing in line with internal goals, but the nature of-and relationship between-the component processes supporting this ability remains poorly understood. Two key components of cognitive control are thought to be the regulation of the declarative contents of working memory (WM) and the selection of task sets, or procedural rules that determine how declarative items are employed. Factor-analytic studies have suggested that updating the items held in WM and updating task sets are cognitively distinct, but interrelated, core domains of executive function. However, the precise relationship between these processes remains unknown, since they have rarely been tested simultaneously in a single task. In the present study, we devised a novel method of independently manipulating declarative item-updating and procedural task-updating processes in WM. Across two experiments, we found that the updating of declarative and procedural WM representations interacted subadditively, suggesting they are not constrained by a common processing bottleneck. Moreover, in a third experiment, we found that updating two declarative items in WM simultaneously did not incur a behavioral cost in response time above and beyond the cost of one item alone. Taken together, our results provide new evidence that the updating of information in declarative and procedural WM is mutually facilitative, such that opening the gate for updating declarative content reduces the time needed to update procedural content, and vice versa.

How do people automatize their dual-task performance through bottleneck bypassing (i.e., accomplish parallel processing of the central stages of two tasks)? In the present work we addressed this question, evaluating the impact of sensory-motor modality compatibility-the similarity in modality between the stimulus and the consequences of the response. We hypothesized that incompatible sensory-motor modalities (e.g., visual-vocal) create conflicts within modality-specific working memory subsystems, and therefore predicted that tasks producing such conflicts would be performed less automatically after practice. To probe for automaticity, we used a transfer psychological refractory period (PRP) procedure: Participants were first trained on a visual task (Exp. 1) or an auditory task (Exp. 2) by itself, which was later presented as Task 2, along with an unpracticed Task 1. The Task 1-Task 2 sensory-motor modality pairings were either compatible (visual-manual and auditory-vocal) or incompatible (visual-vocal and auditory-manual). In both experiments we found converging indicators of bottleneck bypassing (small dual-task interference and a high rate of response reversals) for compatible sensory-motor modalities, but indicators of bottlenecking (large dual-task interference and few response reversals) for incompatible sensory-motor modalities. Relatedly, the proportion of individuals able to bypass the bottleneck was high for compatible modalities but very low for incompatible modalities. We propose that dual-task automatization is within reach when the tasks rely on codes that do not compete within a working memory subsystem.

In this study we used the method of constant stimuli to investigate introspective reaction times in the psychological refractory period (PRP) paradigm under different temporal contexts. Previous introspective PRP studies have mostly used visual analogue scales to assess introspective reaction times and found that participants were largely unaware of the typical dual-task costs that arise in this paradigm (PRP effect). This apparent limitation of introspection has been taken as evidence for a serial processing bottleneck that encompasses response selection as well as conscious perception. In our study, in each trial participants first performed the PRP task and were then presented with a comparison interval that they had to compare with their reaction time to the second task (RT2). Across three experiments, we observed that the subjective estimates of RT2 (i.e., the points of subjective equality) did not reflect the objective pattern but were almost completely biased toward the center of the comparison intervals (asymmetry effect). In a control experiment in which participants discriminated RT2s of other participants without performing the PRP task, this bias was largely reduced. We interpret these results as indicating that in dual-task performance participants acquire only poor temporal representations of their own reaction times, and the apparent unawareness of the PRP effect may reflect disturbed timing abilities rather than a conscious perception bottleneck.