Task-set inhibition in chunked task sequences

Exploring the hierarchical control relationship between different levels of representation and processing is important for understanding how the mind controls itself. In the present study, the relationship between chunking (a sequence-level process) and task-set inhibition (a task-level process) in the performance of task sequences was investigated to evaluate the hypothesis that within-chunk facilitation reduces then−2 repetition cost (slower performance forn−2 task repetitions than forn−2 task switches) attributed to task-set inhibition. An experiment is reported in which subjects were induced to chunk sequences such thatn−2 repetitions occurred within or between chunks. Direct evidence of chunking was obtained, andn−2 repetition cost was smaller whenn−2 repetitions occurred within chunks than between chunks. These findings are consistent with an elaborated hypothesis that attributes the reduction inn−2 repetition cost to priming of task goals rather than direct modulation of task-set inhibition.     

Linking inhibition to activation in the control of task sequences

Inhibition of abandoned tasks in task switching can be inferred when a worse performance is found withn− 2 task repetitions (ABA sequences) than with nonrepetitions (CBA sequences). Recent evidence has shown that this inhibition effect decreases with long intertrial intervals (i.e., response-cue intervals, RCIs). Two alternatives have been proposed to account for this decrease. One alternative attributes the observed decrease to the decay of inhibition itself. The other alternative proposes that decay of the activation of competing tasks reduces the interference and leads to less inhibition. To decide between these alternatives, we manipulated RCI trialwise. The results favor the decay-of-activation account as an explanation for the decreased inhibition effect. This links the amount of inhibition to the activation level of the competing tasks, whereas evidence for the decay of inhibition remains weak.     

Episodic and semantic components of the compound-stimulus strategy in the explicit task-cuing procedure

The explicit task-cuing procedure is commonly used to study executive control processes involved in set switching, but performance in this task-switching procedure may be accomplished without switching tasks. Subjects may perform both tasks by using a compound-stimulus strategy, in which subjects encode the cue, encode the target, and use the combination as a compound retrieval cue to choose the appropriate response. We manipulated the number of targets (8, 16,32, or 640) that subjects experienced in a four-cue/two-task procedure to separate episodic and semantic memory retrieval components of the compound-stimulus strategy. Cue repetitions were faster than task repetitions, and task repetitions were only slightly faster than task alternations, suggesting that cue repetition effects account for the bulk of the difference between repetitions and alternations. We found the same effects with all target set sizes. The results are consistent with use of a semantic compound-stimulus strategy.     

任务切换理论争议新证据

任务切换是研究认知控制的主要范式之一。大量研究发现切换试次比重复试次的反应时更长,错误率更高,这种差异称为切换代价。任务切换时所产生切换代价的理论解释主要有惯性论、重构论和联结论。近十年来,这些理论均获得新的实验支持和发展,但其争议依旧,没有哪一理论能成功解释任务切换的所有效应。未来研究可以建立整合模型,以准确描述切换代价产生的认知机制。     

Inhibition of irrelevant category–response mappings

When switching tasks, performance tends to be worse for n – 2 repetitions than with n – 2 switches. This n – 2 repetition cost has been hypothesized to reflect task-set inhibition: specifically, inhibition of irrelevant category–response mappings involved in response selection. This hypothesis leads to divergent predictions for situations in which all tasks involve the same stimulus categories: An n – 2 repetition cost is predicted when response sets differ across tasks, but not when the response set stays the same. The authors tested these predictions by having subjects perform relative judgements with different reference points. In Experiment 1, the stimulus categories were the same across reference points, but the response set either differed or stayed the same (the multiple- and single-mapping conditions, respectively). An n – 2 repetition cost was found in the multiple-mapping condition but not in the single-mapping condition. Experiment 2 provided evidence against the possibility that these divergent effects reflected differences in memory load. These findings confirm predictions that link n – 2 repetition costs to inhibition of irrelevant category–response mappings.     

The role of inhibition in task switching: A review

The concept of inhibition plays a major role in cognitive psychology. In the present article, we review the evidence for the inhibition of task sets. In the first part, we critically discuss empirical findings of task inhibition from studies that applied variants of the task-switching methodology and argue that most of these findings— such as switch cost asymmetries—are ambiguous. In the second part, we focus on n-22 task-repetition costs, which currently constitute the most convincing evidence for inhibition of task sets. n-22 repetition costs refer to the performance impairment in sequences of the ABA type relative to CBA, which can be interpreted in terms of persisting inhibition of previously abandoned tasks. The available evidence suggests that inhibition is primarily triggered by conflict at selection of stimulus attributes and at the response level. Author Note     

Increased training complexity reduces the effectiveness of brief working memory training: evidence from short-term single and dual n-back training interventions

N-back training has recently come under intense scientific scrutiny due to reports of training-related improvements in general fluid intelligence. As of yet, relatively little is known about the effects of short-term n-back training interventions, however. In a pretest-training-posttest design, we compared brief dual and single n-back training regimen in terms of training gains and transfer effects relative to a passive control group. Transfer effects indicated that, in the short-term, single n-back training may be the more effective training task: At the short training duration we employed, neither training group showed far transfer to specific task switch costs, Stroop inhibition costs or matrix reasoning indexing fluid intelligence. Yet, both types of training resulted in a reduction of general task switch costs indicating improved cognitive control during the sustained maintenance of competing task sets. Single but not dual n-back training additionally yielded near transfer to an untrained working memory updating task.     

Task-set switching and long-term memory retrieval

The authors tested the hypothesis of a close relationship between the intentional component of task-set switching ("advance reconfiguration;" R. D. Rogers & S. Monsell, 1995) and long-term memory (LTM) retrieval. Consistent with this hypothesis, switch costs are reported to be larger when the switched-to task involves high retrieval demands (i.e., retrieval of episodic information) than when it involves low retrieval demands (i.e., retrieval of semantic information). In contrast, switch costs were not affected by a primary-task difficulty manipulation unrelated to intentional retrieval demands (Experiment 2). Also, the retrieval-demand effect on switch costs was eliminated when time for advanced preparation or task cues explicitly specifying the task rules were provided (Experiment 3). Overall, results were consistent with the hypothesis that the intentional switch-cost component reflects the time demands of retrieving appropriate task rules from LTM.     

Exploring temporal dissipation of attention settings in auditory task switching

Using a cued auditory task-switching variant of dichotic listening, we varied the response–cue interval (RCI) to examine temporal dissipation effects. On each trial, participants were presented with two different number words, one spoken by a female speaker and another by a male speaker (dichotic listening), that served as competing targets for a numerical judgment. The gender of the task-relevant speaker was indicated by a visual task cue prior to each trial. Experiment 1A used two different cues for each task (i.e., gender) and showed only small cue repetition benefits (same cue vs. alternate cue) but large auditory switch costs (alternate cue vs. task switch). A replication without immediate cue repetitions (Experiment 1B) showed very similar switch costs, suggesting that immediate cue repetitions play a negligible role for the size of auditory task switch costs. Moreover, switch costs were reduced when the (entirely task-irrelevant) location of the task-relevant speaker changed, relative to when it was unchanged, suggesting an episodic feature-binding component in our dichotic-listening task. Importantly, both experiments showed no effect of RCI on auditory switch costs. Because statistical power for this null effect was reasonably high across experiments (n?=?50), this finding suggests that auditory attention settings do not dissipate quickly over time.     

Sticky plans: Inhibition and binding during serial-task control

Recent evidence suggests substantial response-time costs associated with lag-2 repetitions of tasks within explicitly controlled task sequences [Koch, I., Philipp, A. M., Gade, M. (2006). Chunking in task sequences modulates task inhibition. Psychological Science, 17, 346-350; Schneider, D. W. (2007). Task-set inhibition in chunked task sequences. Psychonomic Bulletin & Review, 14, 970-976], a result that has been interpreted as inhibition of no-longer relevant tasks. Experiments 1-3 confirm much larger lag-2 costs under serial-control than under externally cued conditions, but also show (a) that these costs occur only when sequences contain at least two distinct chunks and (b) that direct lag-2 repetitions are not a necessary condition for their occurrence. This pattern suggests the hypothesis that rather than task-set inhibition, the large lag-2 costs observed in complex sequences, reflect interference resulting from links between positions within a sequential plan and the individual tasks controlled by this plan. The remaining experiments successfully test this hypothesis (Experiment 4), rule out chaining accounts as a potential alternative explanation (Experiment 5), and demonstrate that interference results from information stored in long-term memory rather than working memory (Experiment 6). Implications of these results for an integration of models of serial-order control and serial memory are discussed.     

Attentional Performance in Children and Adolescents with Tic Disorder and Co-Occurring Attention-Deficit/Hyperactivity Disorder: New Insights from a 2 × 2 Factorial Design Study

The aim of the present study was to investigate the effect of both tic disorder (TD) and attention-deficit/hyperactivity disorder (ADHD) on attentional functions. N = 96 children and adolescents participated in the study, including n = 21 subjects with TD, n = 23 subjects with ADHD, n = 25 subjects with TD+ADHD, and n = 27 controls. Attentional performance was tested based on four computerized attention tasks (sustained attention, divided attention, go/nogo and set shifting). The effect of TD as well as ADHD on attentional performance was tested using a 2 × 2 factorial approach. A diagnosis of TD had no negative impact on attentional functions but was associated with improved performance in the set shifting task. By contrast, regardless of a diagnosis of TD, subjects with ADHD were found to perform worse in the sustained attention, divided attention and go/nogo task. No interaction effect between the factors TD and ADHD was revealed for any of the attention measures. Our results add to findings from other areas of research, showing that in subjects with TD and ADHD, ADHD psychopathology is often the main source of impairment, whereas a diagnosis of TD has little or no impact on neuropsychological performance in most cases and even seems to be associated with adaptive mechanisms.     

The effect of practice on n–2 repetition costs in set switching

Inhibition in set switching is inferred from so-called n–2 repetition costs: slower response times to ABA sequences compared to CBA sequences (where A, B, and C are arbitrary labels for different tasks). These costs are thought to reflect the persisting inhibition of task A when it was disengaged recently (as is the case in an ABA sequence). In this study we were interested in whether more inhibition may be required when the tasks are relatively novel. To this end, we examined the effect of practice on the n–2 repetition cost in nine participants across five experimental sessions, with 1222 trials performed in each session. The results show a clear reduction in the n–2 repetition cost, being altogether absent from the final sessions. Such a reduction is predicted by both: (a) a recent computational model of the n–2 repetition cost (Grange, Juvina, & Houghton, 2013) due to the gradual strengthening of task-related memory elements with practice to the point where inhibition has less impact; and (b) prior work showing smaller n–2 repetition costs with greater cue–target association strength (Houghton, Pritchard, & Grange, 2009). In this paper, we integrate these two theoretical derivations by extending our computational model, which fit the current data—at the mean level, block level, and individual-subject (i.e., individual differences) level—well.     

Gesture Helps,Only If You Need It: Inhibiting Gesture Reduces Tip-of-the-Tongue Resolution for Those With Weak Short-Term Memory

People frequently gesture when a word is on the tip of their tongue (TOT), yet research is mixed as to whether and why gesture aids lexical retrieval. We tested three accounts: the lexical retrieval hypothesis, which predicts that semantically related gestures facilitate successful lexical retrieval; the cognitive load account, which predicts that matching gestures facilitate lexical retrieval only when retrieval is hard, as in the case of a TOT; and the motor movement account, which predicts that any motor movements should support lexical retrieval. In Experiment 1 (a between-subjects study; N = 90), gesture inhibition, but not neck inhibition, affected TOT resolution but not overall lexical retrieval; participants in the gesture-inhibited condition resolved fewer TOTs than participants who were allowed to gesture. When participants could gesture, they produced more representational gestures during resolved than unresolved TOTs, a pattern not observed for meaningless motor movements (e.g., beats). However, the effect of gesture inhibition on TOT resolution was not uniform; some participants resolved many TOTs, while others struggled. In Experiment 2 (a within-subjects study; N = 34), the effect of gesture inhibition was traced to individual differences in verbal, not spatial short-term memory (STM) span; those with weaker verbal STM resolved fewer TOTs when unable to gesture. This relationship between verbal STM and TOT resolution was not observed when participants were allowed to gesture. Taken together, these results fit the cognitive load account; when lexical retrieval is hard, gesture effectively reduces the cognitive load of TOT resolution for those who find the task especially taxing.     

Priming cue encoding by manipulating transition frequency in explicitly cued task switching

Explicitly cued task switching with multiple cues per task permits three types of transitions: cue repetitions (cue and task repeat), task repetitions (cue changes but task repeats), and task alternations (cue and task change). The difference between task alternations and task repetitions can be interpreted as a switch cost, but its magnitude varies substantially across experiments. We investigated how switch cost is affected by transition frequency (how often subjects repeat and switch tasks) with an experiment in which each transition had a frequency of .70 in separate sessions. Switch cost was smallest when task alternations were frequent and largest when task repetitions were frequent. Mathematical modeling of the data indicated that the different “switch costs” reflected priming of cue encoding for frequent transitions. Interpretations of our findings based on automatic priming from memory retrieval of past transitions and strategic priming from transition expectancies are discussed.     

Collaboration and Memory: Effects of Dyadic Retrieval on Different Memory Tasks

Collaborative retrieval was investigated in two experiments. The experiments were explicitly designed to investigate how different types of memory tasks were affected by two individuals working together compared to individuals working on their own. A nominal group score was treated as the predicted potential a dyad could attain. In Experiment 1, semantic and episodic retrieval were employed. The episodic task was to encode and retrieve a story and the semantic task was to answer, without any encoding, 20 questions from the same history domain as the episodic task. In Experiment 2, explicit recognition and implicit retrieval of dot patterns were employed. The explicit recognition task was forced-choice, and in the implicit task, subjects were instructed to complete a pattern they saw from an incomplete pattern. The results suggest that: (1) dyads suffer from collaboration relative to the predicted potential, (2) the reduction of productivity for dyads was limited to explicit and episodic memory tasks, and (3) friends as opposed to non-friends reduced the negative effect of collaboration. The results replicate and extend the results from a previous study.     

Part-set cueing and lexical decisions: Testing an inhibitory account

Providing some elements of a studied set during testing (part-set cues) can impair memory for the remaining elements (noncues)—a counterintuitive effect that has recently been attributed to inhibition of noncues. To test for such inhibition using a lexical decision task, we manipulated semantic and episodic relationships, such that cues and noncues were related only semantically, only episodically, or both semantically and episodically. Results showed that part-set cueing evoked inhibition, slowing lexical decisions for noncues that were related to cues both semantically and episodically, consistent with previous results involving the retrieval practice paradigm. However, either type of relationship alone was insufficient to slow decisions, despite previous evidence of impaired memory in similar conditions when tested with other measures such as free recall. The latter results raise questions regarding the extent to which inhibition can account for cueing-induced impairment when cues and noncues are related only semantically or only episodically.     

Lower bounds for the reliability of the total score on a test composed of non-homogeneous items: II: A search procedure to locate the greatest lower bound

Finding the greatest lower bound for the reliability of the total score on a test comprisingn non-homogenous items with dispersion matrix Σ _x is equivalent to maximizing the trace of a diagonal matrix Σ _E with elements θ _I , subject to Σ _E and Σ _T =Σ _x − Σ _E being non-negative definite. The casesn=2 andn=3 are solved explicity. A computer search in the space of the θ _i is developed for the general case. When Guttman's λ₄ (maximum split-half coefficient alpha) is not the g.l.b., the maximizing set of θ _i makes the rank of Σ _T less thann − 1. Numerical examples of various bounds are given. Present affiliation of the first author: St. Hild's College of Education, Durham City, England.     

Cohen’s Linearly Weighted Kappa is a Weighted Average of 2×2 Kappas

An agreement table with n∈ℕ_≥3 ordered categories can be collapsed into n−1 distinct 2×2 tables by combining adjacent categories. Vanbelle and Albert (Stat. Methodol. 6:157–163, 2009c) showed that the components of Cohen’s weighted kappa with linear weights can be obtained from these n−1 collapsed 2×2 tables. In this paper we consider several consequences of this result. One is that the weighted kappa with linear weights can be interpreted as a weighted arithmetic mean of the kappas corresponding to the 2×2 tables, where the weights are the denominators of the 2×2 kappas. In addition, it is shown that similar results and interpretations hold for linearly weighted kappas for multiple raters.     

Examining Manual and Visual Response Inhibition Among ADHD Subtypes

This study compared inhibitory functioning among ADHD subtype groups on manual and visual versions of the stop task. Seventy-six children, identified as ADHD/I (n = 17), ADHD/C (n = 43), and comparison (n = 20) completed both tasks. Results indicated that both ADHD groups were slower to inhibit responses than the comparison group on both tasks. Comparison children were faster to inhibit than activate responses on both tasks. Children in the ADHD groups also demonstrated this robust pattern on the manual task. However, on the visual task, the ADHD groups evidenced slowed inhibition comparable to the time required to activate responding. This implies that the visual task is more sensitive than the manual task to inhibitory deficits associated with ADHD. The ADHD/I and the ADHD/C groups did not differ on most measures, suggesting that neither stop task is effective in differentiating the subtypes. These findings extend work highlighting the role of disinhibition in ADHD, and contrast recent work suggesting divergence between ADHD subtypes.     

Developmental Trajectories of Perceived Friendship Intimacy,Constructive Problem Solving,and Depression from Early to Late Adolescence

This study examined friendship types in developmental trajectories of perceived closeness and balanced relatedness. In addition, differences between friendship types in the development of constructive problem solving and depression were examined. Questionnaire data of five annual waves were used from two adolescent cohorts (cohort 1: M = 12.41 years; cohort 2: M = 16.37 years). Growth Mixture Modeling revealed two developmental trajectories in cognitive representations of perceived friendship intimacy: interdependent and disengaged friendships. Adolescents in interdependent friendships were characterized by high perceived closeness and balanced relatedness across adolescence. Furthermore, adolescents in disengaged friendships had lower levels of and smaller increases in constructive problem solving. Girls in disengaged friendships showed smaller increases in balanced relatedness and higher levels of depression than boys in disengaged friendships and adolescents in interdependent friendships.