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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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).

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.

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.

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.

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).

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.

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.

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.

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.

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.

Using brain imaging to track problem solving in a complex state space.

This paper describes how behavioral and imaging data can be combined with a Hidden Markov Model (HMM) to track participants' trajectories through a complex state space. Participants completed a problem-solving variant of a memory game that involved 625 distinct states, 24 operators, and an astronomical number of paths through the state space. Three sources of information were used for classification purposes.

Modeling fan effects on the time course of associative recognition.

We investigated the time course of associative recognition using the response signal procedure, whereby a stimulus is presented and followed after a variable lag by a signal indicating that an immediate response is required. More specifically, we examined the effects of associative fan (the number of associations that an item has with other items in memory) on speed-accuracy tradeoff functions obtained in a previous response signal experiment involving briefly studied materials and in a new experiment involving well-learned materials. High fan lowered asymptotic accuracy or the rate of rise in accuracy across lags, or both.

Task-switching performance with 1:1 and 2:1 cue-task mappings: not so different after all.

When task-switching studies use the task-cuing procedure with a 1:1 cue-task mapping, task switching and cue switching are confounded, which is problematic for interpreting switch costs. The use of a 2:1 cue-task mapping is a potential solution to this problem, but it is possible that introducing more cues may also introduce marked changes in task-switching performance. In 5 experiments involving 160 subjects, the authors compared performance with 1:1 and 2:1 mappings across several methodological changes.

A memory-based model of Hick's law.

We propose and evaluate a memory-based model of Hick's law, the approximately linear increase in choice reaction time with the logarithm of set size (the number of stimulus-response alternatives). According to the model, Hick's law reflects a combination of associative interference during retrieval from declarative memory and occasional savings for stimulus-response repetitions due to non-retrieval. Fits to existing data sets show that the model accounts for the basic set-size effect, changes in the set-size effect with practice, and stimulus-response repetition effects that challenge the information-theoretic view of Hick's law.

The target of task switching.

Task switching involves processing target stimuli in accordance with a frequently changing series of tasks. An outstanding issue is whether this processing is tailored to the perceptual or categorical representation of targets. To address this issue, the authors compared switch costs in responding to targets that were perceptually distinct (words and images) but associated with the same categories (colors and shapes).