Partitioning switch costs when investigating task switching in relation to media multitasking.

The prevalence of media multitasking - the concurrent use of multiple forms of media - has motivated research on whether and how it is related to various cognitive abilities, such as the ability to switch tasks. However, previous research on the relationship between media multitasking and task-switching performance has yielded mixed results, possibly because of small sample sizes and a confound between task and cue transitions that resulted in switch costs being impure measures of task-switching ability. The authors conducted a large-sample study in which media multitasking behavior was surveyed and task-switching performance was assessed using two cues per task, thereby allowing switch costs to be partitioned into task-switching and cue-repetition effects. The main finding was no evidence of any relationship between media multitasking scores and task-switching effects (or cue-repetition effects), either in correlational analyses or in extreme group analyses of light and heavy media multitaskers. The results are discussed in the context of previous research, with implications for studying media multitasking in relation to task-switching performance.

Alertness and cognitive control: Interactions in the spatial Stroop task.

Cognitive control over information processing can be implemented by selective attention, but it is often suboptimal, as indicated by congruency effects arising from processing of irrelevant stimulus features. Research has revealed that congruency effects in some tasks are larger when subjects are more alert, and it has been suggested that this alerting-congruency interaction might be associated with spatial information processing. The author investigated the generality of the interaction by conducting a preregistered set of four experiments in which alertness was manipulated in variants of the spatial Stroop task, which involved classifying the spatial meaning of a stimulus presented at an irrelevant position. Regardless of stimulus type (arrows or words) and spatial dimension (horizontal or vertical), significant alerting-congruency interactions for response times were found in all experiments. The results are consistent with the suggestion that spatial attention and spatial information processing are important sources of the interaction, with implications for understanding how alertness is related to cognitive control.

On the Role of Attention in Working Memory for Response Selection in Task Switching.

Oberauer's (2019) analysis and related research on how working memory and attention are linked can provide insight regarding how responses are selected in task-switching situations. One mechanism for response selection-the mediated route-categorizes stimuli with respect to both tasks, then activates responses based on instructed category-response associations. The author discusses two proposals for how these associations are represented in working memory, both of which seem consistent with the idea that attention selects or prioritizes the relevant-task associations, enabling accurate response selection. A broader implication of the representation and operation of the mediated route is that nominal task switching might reflect concurrent multitasking within the cognitive system (constrained by attention in working memory), raising the issue of how task switching should be characterized.

Alertness and cognitive control: Testing the spatial grouping hypothesis.

Alertness seems to influence selective attention processes underlying cognitive control in the flanker task, as indicated by previous findings of larger congruency effects on alert trials (in which task stimuli are preceded by alerting cues) than on no-alert trials. One hypothesis for the alerting-congruency interaction is that increased alertness promotes spatial grouping of the target and distractors. In the present study, the author tested the spatial grouping hypothesis in three experiments in which the spatial alignment (collinearity) of the target and distractors was manipulated. Reliable alerting-congruency interactions were obtained, and congruency effects on response times were smaller for misaligned stimuli than for aligned stimuli in all experiments. However, the alerting-congruency interactions were not consistently modulated by alignment, contrary to a prediction derived from the spatial grouping hypothesis. The results suggest that spatial grouping is not a viable mechanism for explaining the alerting-congruency interaction in the flanker task, helping to prune the space of theoretical possibilities for linking alertness to cognitive control.

Alertness and cognitive control: Is there a spatial attention constraint?

Congruency effects in arrow flanker tasks are often larger when subjects are more alert, suggesting an unusual connection between alertness and cognitive control. Theoretical accounts of the alerting-congruency interaction differ with respect to whether and how spatial attention is involved. In the present study, the author conducted eight experiments to determine whether there is a spatial attention constraint linking alertness to cognitive control. Alertness was manipulated in color-word Stroop tasks involving stimuli that were spatially integrated (Experiments 1-3) or separated (Experiments 4 and 5), as well as in Stroop-like tasks involving spatially separated stimuli for which the irrelevant stimulus features were spatial words (Experiments 6 and 7) or arrows (Experiment 8). All experiments yielded effects of alerting and congruency, but none produced the alerting-congruency interaction typically found with arrow flanker tasks. The results suggest that there is a spatial attention constraint on the relationship between alertness and cognitive control, part of which might involve having a task goal associated with spatial information processing.

Alertness and cognitive control: Toward a spatial grouping hypothesis.

A puzzling interaction involving alertness and cognitive control is indicated by the finding of faster performance but larger congruency effects on alert trials (on which alerting cues are presented before the task stimuli) than on no-alert trials in selective attention tasks. In the present study, the author conducted four experiments to test hypotheses about the interaction. Manipulation of stimulus spacing revealed a difference in congruency effects between alert and no-alert trials for narrowly spaced stimuli but not for widely spaced stimuli, inconsistent with the hypothesis that increased alertness is associated with more diffuse attention. Manipulation of color grouping revealed similar differences in congruency effects between alert and no-alert trials for same-color and different-color groupings of targets and distractors, inconsistent with the general hypothesis that increased alertness is associated with more perceptual grouping. To explain the results, the author proposes that increased alertness is associated specifically with more spatial grouping of stimuli, possibly by modulating the threshold for parsing stimulus displays into distinct objects.

Hick's law for choice reaction time: A review.

In 1952, W. E. Hick published an article in the Quarterly Journal of Experimental Psychology, "On the rate of gain of information." It played a seminal role in the cognitive revolution and established one of the few widely acknowledged laws in psychology, relating choice reaction time to the number of stimulus-response alternatives (or amount of uncertainty) in a task. We review the historical context in which Hick conducted his study and describe his experiments and theoretical analyses. We discuss the article's immediate impact on researchers, as well as challenges to and shortcomings of Hick's law and his analysis, including effects of stimulus-response compatibility, practice, very large set sizes and sequential dependencies. Contemporary modeling developments are also described in detail. Perhaps most impressive about Hick's law is that it continues to spawn research efforts to the present and that it is regarded as a fundamental law of interface design for human-computer interaction using technologies that did not exist at the time of Hick's research.

Categorization difficulty modulates the mediated route for response selection in task switching.

Conflict during response selection in task switching is indicated by the response congruency effect: worse performance for incongruent targets (requiring different responses across tasks) than for congruent targets (requiring the same response). The effect can be explained by dual-task processing in a mediated route for response selection, whereby targets are categorized with respect to both tasks. In the present study, the author tested predictions for the modulation of response congruency effects by categorization difficulty derived from a relative-speed-of-processing hypothesis. Categorization difficulty was manipulated for the relevant and irrelevant task dimensions in a novel spatial task-switching paradigm that involved judging the locations of target dots in a grid, without repetition of dot configurations. Response congruency effects were observed and they varied systematically with categorization difficulty (e.g., being larger when irrelevant categorization was easy than when it was hard). These results are consistent with the relative-speed-of-processing hypothesis and suggest that task-switching models that implement variations of the mediated route for response selection need to address the time course of categorization.

Alertness and cognitive control: Testing the early onset hypothesis.

Previous research has revealed a peculiar interaction between alertness and cognitive control in selective-attention tasks: Congruency effects are larger on alert trials (on which an alerting cue is presented briefly in advance of the imperative stimulus) than on no-alert trials, despite shorter response times (RTs) on alert trials. One explanation for this finding is the early onset hypothesis, which is based on the assumptions that increased alertness shortens stimulus-encoding time and that cognitive control involves gradually focusing attention during a trial. The author tested the hypothesis in 3 experiments by manipulating alertness and stimulus quality (which were intended to shorten and lengthen stimulus-encoding time, respectively) in an arrow-based flanker task involving congruent and incongruent stimuli. Replicating past findings, the alerting manipulation led to shorter RTs but larger congruency effects on alert trials than on no-alert trials. The stimulus-quality manipulation led to longer RTs and larger congruency effects for degraded stimuli than for intact stimuli. These results provide mixed support for the early onset hypothesis, but the author discusses how data and theory might be reconciled if stimulus quality affects stimulus-encoding time and the rate of evidence accumulation in the decision process. (PsycINFO Database Record

Visual selective attention with virtual barriers.

Previous studies have shown that interference effects in the flanker task are reduced when physical barriers (e.g., hands) are placed around rather than below a target flanked by distractors. One explanation of this finding is the referential coding hypothesis, whereby the barriers serve as reference objects for allocating attention. In five experiments, the generality of the referential coding hypothesis was tested by investigating whether interference effects are modulated by the placement of virtual barriers (e.g., parentheses). Modulation of flanker interference was found only when target and distractors differed in size and the virtual barriers were beveled wood-grain objects. Under these conditions and those of previous studies, the author conjectures that an impression of depth was produced when the barriers were around the target, such that the target was perceived to be on a different depth plane than the distractors. Perception of depth in the stimulus display might have led to referential coding of the stimuli in three-dimensional (3-D) space, influencing the allocation of attention beyond the horizontal and vertical dimensions. This 3-D referential coding hypothesis is consistent with research on selective attention in 3-D space that shows flanker interference is reduced when target and distractors are separated in depth.

Phasic alertness and residual switch costs in task switching.

Residual switch costs are deficits in task-switching performance that occur despite considerable time to prepare for a task switch. In the present study, the author investigated whether increased phasic alertness modulates residual switch costs. In 2 experiments involving the task-cuing procedure, subjects performed numerical categorization tasks on target digits, with and without an alerting stimulus presented shortly before the target (alert and no-alert trials, respectively). Switch costs were obtained that decreased with a longer cue-target interval, indicating subjects engaged in preparation, but large residual switch costs remained. Alerting effects were obtained in the form of faster overall performance on alert than on no-alert trials, indicating the alerting stimuli increased phasic alertness. Critically, residual switch costs were similar on alert and no-alert trials in both experiments, unaffected by manipulations of alert type, alert availability, and alert-target interval. Implications of the results for understanding the relationship between phasic alertness and cognitive control in task switching are discussed. (PsycINFO Database Record

Investigating a method for reducing residual switch costs in cued task switching.

Residual switch costs in cued task switching are performance decrements that occur despite a long cue-target interval (CTI) to prepare for a task switch. Verbruggen, Liefooghe, Vandierendonck, and Demanet (Journal of Experimental Psychology: Learning, Memory, and Cognition, 33; 342-356, 2007) showed that briefly presenting the cue during the CTI and leaving it absent after target onset yielded smaller residual switch costs than those obtained when the cue was available for the full CTI and remained present after target onset. The potential effects of cue availability during the CTI (full or partial) and cue status after target onset (present or absent) on residual switch costs were investigated in the present study. In Experiments 1 and 2, cue status was manipulated while holding cue availability constant. In Experiments 3 and 4, cue status and cue availability were manipulated factorially. Residual switch costs were obtained, but they were not modulated consistently by cue status or cue availability across experiments. In Experiment 5, a direct replication of one of Verbruggen and colleagues' experiments yielded divergent results. Implications for understanding task switching are discussed.

Perceptual and conceptual priming of cue encoding in task switching.

Transition effects in task-cuing experiments can be partitioned into task switching and cue repetition effects by using multiple cues per task. In the present study, the author shows that cue repetition effects can be partitioned into perceptual and conceptual priming effects. In 2 experiments, letters or numbers in their uppercase/lowercase or word/numeral forms, respectively, served as cues for perceptual categorization tasks (e.g., the letters B, b, E, and e were cues for a color judgment and the letters D, d, G, and g were cues for a shape judgment). Some cues represented the same concept but had different percepts, allowing nominal repetitions to occur across trials (e.g., d followed by D). Conceptual priming effects were measured by comparing relational repetitions (e.g., G followed by D) with nominal repetitions, whereas perceptual priming effects were measured by comparing nominal repetitions with physical repetitions (e.g., D followed by D). Large conceptual and perceptual priming effects on response time were observed. Implications of the results for understanding cue encoding in task switching situations are discussed. (PsycINFO Database Record

Attentional control of response selection in task switching.

Modulation of cognitive control was investigated by using a proportion congruent manipulation to change response congruency effects in task switching. In an experiment that involved cued switching between semantic categorization tasks, targets were either congruent or incongruent (mapped to the same or different responses across tasks, respectively), and the proportion of congruent targets was manipulated between subjects. Response congruency effects (worse performance for incongruent than for congruent targets) were observed, and they increased with proportion congruent for both response time and error rate. A sequential congruency effect (a smaller response congruency effect following an incongruent than a congruent trial) was observed for error rate, but only for task repetitions. The results suggested top-down control of attention rather than bottom-up control based on item-specific learning, because targets were never repeated during the experiment. Implications for understanding attentional control of response selection in conflict situations are discussed.

Learning a nonmediated route for response selection in task switching.

Two modes of response selection--a mediated route involving categorization and a nonmediated route involving instance-based memory retrieval--have been proposed to explain response congruency effects in task-switching situations. In the present study, we sought a better understanding of the development and characteristics of the nonmediated route. In two experiments involving training and transfer phases, we investigated practice effects at the level of individual target presentations, transfer effects associated with changing category-response mappings, target-specific effects from comparisons of old and new targets during transfer, and the percentages of early responses associated with task-nonspecific response selection (the target preceded the task cue on every trial). The training results suggested that the nonmediated route is quickly learned in the context of target-cue order and becomes increasingly involved in response selection with practice. The transfer results suggested that the target-response instances underlying the nonmediated route involve abstract response labels coding response congruency that can be rapidly remapped to alternative responses, but not rewritten when category-response mappings change after practice. Implications for understanding the nonmediated route and its relationship with the mediated route are discussed.

Chunking away task-switch costs: a test of the chunk-point hypothesis.

Previous research has revealed that task-switch costs (worse performance for task switches than for task repetitions) at the first position of an explicit task sequence are eliminated or reduced when repeating or switching sequences. The authors hypothesize that such effects are restricted to points in the sequence representation that are associated with sequence-level processing such as chunk retrieval that changes the contents of working memory. In an experiment testing this chunk-point hypothesis, subjects memorized and performed explicit task sequences under different chunking instructions that induced chunk points at different positions within the sequences. Regardless of position, performance was slower at chunk points than at non-chunk points, providing direct evidence of chunking, and task-switch costs were reduced or eliminated at chunk points while they remained large and robust at non-chunk points. These findings support the chunk-point hypothesis and are discussed in relation to task-set inhibition and associative interference.

Isolating a mediated route for response congruency effects in task switching.

Response congruency effects in task switching reflect worse performance for incongruent targets associated with different responses across tasks than for congruent targets associated with the same response. In the present study, the author investigated whether the effects can be produced solely by a mediated route for response selection, whereby targets are categorized with respect to both tasks, as opposed to a nonmediated route, whereby target-response instances from past experience are retrieved directly from long-term memory. The mediated route was isolated in 3 experiments by having subjects perform semantic categorization tasks on targets that were never repeated, thereby making the nonmediated route nonfunctional. Robust response congruency effects were observed for both response time and error rate in all experiments, indicating that the mediated route is sufficient to produce such effects by itself. The results imply that subjects engaged in dual-task processing despite no requirement to do so, raising questions about the modeling of response selection in task-switching situations.

Modeling graded response congruency effects in task switching.

Compound cue retrieval is a computational model of a mediated route for response selection in task-switching situations. In previous studies, the model has been shown to account for response congruency effects when switching between two tasks, where response congruency reflects the degree of match between relevant and irrelevant task responses associated with a target stimulus. In the present study, the author derived a model prediction of graded response congruency effects in situations involving three tasks. The predicted pattern was observed for both response time and error rate in an experiment in which numerical categorization tasks were performed on single-digit targets. Implications for understanding response congruency effects and for developing models of task-switching performance are discussed.

Modelling response selection in task switching: testing the contingent encoding assumption.

The contingent encoding assumption is the idea that response selection in task-switching situations does not begin until the cue and the target have both been encoded. The authors tested the assumption by manipulating response congruency, stimulus order, and stimulus onset asynchrony (SOA) in two experiments. They found evidence of response selection prior to cue encoding for congruent targets with target-cue order at a long SOA, indicating that the contingent encoding assumption is invalid. The authors describe how contingent encoding can be removed from an existing task-switching model by introducing baseline evidence--task-neutral evidence that serves as a baseline for response selection prior to stimulus encoding. Simulations revealed that the modified model could reproduce the full pattern of response time data and generate responses prior to cue encoding. The authors conclude by discussing directions for further model development.

Stages of processing in associative recognition: evidence from behavior, EEG, and classification.

In this study, we investigated the stages of information processing in associative recognition. We recorded EEG data while participants performed an associative recognition task that involved manipulations of word length, associative fan, and probe type, which were hypothesized to affect the perceptual encoding, retrieval, and decision stages of the recognition task, respectively. Analyses of the behavioral and EEG data, supplemented with classification of the EEG data using machine-learning techniques, provided evidence that generally supported the sequence of stages assumed by a computational model developed in the Adaptive Control of Thought-Rational cognitive architecture. However, the results suggested a more complex relationship between memory retrieval and decision-making than assumed by the model. Implications of the results for modeling associative recognition are discussed. The study illustrates how a classifier approach, in combination with focused manipulations, can be used to investigate the timing of processing stages.