Exploring task-set reconfiguration with random task sequences

Switching between two different tasks normally results in an impairment in people's performance known as a switch cost, typically measured as an increase in reaction time (RT) and errors compared to a situation in which no task switch is required. Researchers in task switching have suggested that this switch cost is the behavioural manifestation of the task set reconfiguration processes that are necessary to perform the upcoming task. However, an examination of the literature in task switching reveals apparently contradictory results about the nature of task set reconfiguration processes. In Experiment 1, we addressed this issue by comparing participants' performance in two different experimental conditions: predictable task switching and random task switching. In the predictable switch condition the switch cost completely vanished after the first repetition of the new task. However, in the random switch condition, while the difference between switch and repetition trials was not significant, we observed a significant reduction in RT between the first and second repetition of the new task. In Experiment 2, we further investigated the pattern of task set reconfiguration in the random switch situation. The results showed a progressive reduction of participants' response latencies across repetitions of the same task. The present study demonstrates that, whereas the results in predictable switching conditions are compatible with an exogenous-reconfiguration hypothesis, random task switching produces a more gradual, decay-like switch cost reduction with task repetition.     

Task-set reconfiguration with predictable and unpredictable task switches

Participants switched frequently between high/low and odd/even classification of a digit. The interval between a task cue and the next digit varied between blocks. In Experiment 1, the task switched predictably every two, four, or eight trials. In Experiment 2, switching predictably every four trials was compared with random switching. With predictable switching, the cost was limited to the first trial of a run. Random switching produced a more gradual approach to asymptotic performance. After one performance, control processes attenuate the resulting change in task-set bias if a further switch is likely, but this strategic modulation is soon overwhelmed by task-set priming through further performances. Preparation reduced switch costs but not interference from the irrelevant attribute: Control of interference appears to be reactive, not proactive. Switch costs did not increase with run length, suggesting that retrieval of the task set last associated with the stimulus did not contribute to switch costs.     

Effects of repetition and foreknowledge in task-set reconfiguration

To examine the roles of executive control and automatic activation in task switching, we manipulated foreknowledge as well as task transitions. In Experiments 1 and 2, performance with foreknowledge was faster than performance with no foreknowledge, but the amount of switch cost did not depend on foreknowledge. This result suggests that switch costs primarily reflect persisting activation rather than inadequate preparation. In Experiment 3, switch cost was greater with foreknowledge about task transition alone than with foreknowledge about both task transition and identity, suggesting that foreknowledge about specific task identity did allow preparation for a switched task. We argue that task repetition and foreknowledge effects are independent. Although foreknowledge allows preparation for both repeated and switched tasks, repeating the same task has benefits over task switching regardless of foreknowledge.     

Effect of arousal increase in predictable and random task switching: evidence for the involvement of the anterior attentional network in random but not in predictable task switching

Switch cost does not disappear as more preparation time for the next task is allowed. Tornay and Milán showed that the residual cost is smaller when tasks switch randomly than when they alternate in predictable sequences. They proposed that the difference was due to control mechanisms (anterior attentional network) being activated in the random condition because of its overall difficulty. Besides, it has been shown that increasing arousal levels inhibits the anterior attentional network. Therefore, Tornay and Milán's account predicts that high arousal should result in switch cost for the random condition increasing to the levels of predictable switching. In this work, this prediction was tested by assessing the interaction between increased arousal and switch cost with both predictable and random-task switching. The results may help to solve the ongoing controversy about the causes of switch cost.     

Adjustments of task-set control processes: Effect of task switch frequency on task-mixing and task-switching costs

The present study tested the hypothesis that task-switch frequency triggers adjustments of task-set control processes. A mixed-task condition where task switches are frequent should promote flexibility—thus improving task-switch performance—whereas a condition where task repetitions are more expected should favour stability—thus improving task-repeat performance. In two experiments, participants performed single-task and mixed-task blocks. In mixed-task blocks, tasks varied randomly on a trial-by-trial basis. For half of the mixed-task blocks, the frequency with which the task changed was 25%, for the other half, it was 50%. Overall, depending on the task-switch frequency, performance on both task-repeat and task-switch trials was modified. Switch cost was reduced and task-repeat performance was altered by the increase in switch probability. This study demonstrates context-sensitive adjustments of task-set control processes. These results further support the view that mixing cost reflects sustained and endogenous components of cognitive control.     

Anticipatory reconfiguration elicited by fully and partially informative cues that validly predict a switch in task

Task-switching studies show no behavioral benefit of partially informative cues. However, ERP evidence of an early cue-locked positivity elicited by both fully and partially informative cues suggests that both cues trigger an anticipatory component of task set reconfiguration (Nicholson, Karayanidis, Davies, & Michie, 2006). We examined this apparent discrepancy using a cued-trials task-switching paradigm with three tasks. The ERP finding of an early cue-locked positivity was replicated for both switch-to cues, which validly predicted an upcoming switch trial and specified the new task set, and switch-away cues, which validly predicted an upcoming switch trial but not the new task set. This component was not elicited by a noninformative cue that did not specify whether the task would switch or repeat. Switch-away cues resulted in more accurate but not faster responding than did noninformative cues. Modeling of decision processes confirmed a speed-accuracy trade-off between these conditions and a preparation benefit for both switch-to and switch-away cues. These results indicate that both fully and partially informative cues elicit an early anticipatory component of task set reconfiguration that is reflected in the early cue-locked positivity. We argue that the pattern of results is most consistent with a task set inhibition account of this early anticipatory component of task set reconfiguration.     

Executive control in set switching: residual switch cost and task-set inhibition.

Executive processes necessary for flexibly switching between different tasks were studied using a set switching paradigm that requires participants to rapidly switch between different tasks across consecutive trials. Switch cost reflects poorer performance for task-switch trials than for consecutive same-task trials. Significant switch cost was observed even with considerable preparation time before a task-switch, an effect known as residual switch cost. This study tested the hypothesis that one process underlying residual switch cost is inhibition of the previous task-set. We used semantic categorization tasks to compare switch cost between alternating task series (ABA) and nonalternating series (ABC) in order to test the generality of a task-set inhibition effect previously observed with perceptual judgment tasks (Mayr & Keele, in press). The results yielded significant switch cost only for alternating tasks, in both response times and errors resulting from performance of the wrong task. Thus, resolving inhibition associated with previously abandoned task-sets may be the main process underlying residual switch costs, suggesting that task-set inhibition is an important executive control process.     

Inner speech sustains predictable task switching: direct evidence in adults

It has been proposed that inner speech supports task selection in task-switching studies, especially when the need for endogenous control is increased. This has been established through the suppression of inner speech in cognitive-flexibility tasks that leads to poorer performance. The aim of this study is to quantify the role of inner speech in a flexibility task by using surface laryngeal electromyography, which, contrary to previous studies, enables participants to freely verbalise the tasks. We manipulated endogenous and exogenous flexibility in a mathematical switching task paradigm. Experiment 1 shows that inner speech acts as a support for switching and is recruited more often when the tasks are of an endogenous type. The main result of Experiment 2 that language is recruited more for the mixing cost than for the switch cost (regardless of the endogenous factor) extends past findings obtained through articulatory suppression.     

Gestalts are more closely associated with performance on a discrimination task than are component stimuli

Distance, similarity, and other components of the physical stimulus but also gestalts are associated with the ability to discriminate between two objects. The present research bears on this confound. Identical lines were added to the opening and closing bracket of a pair of brackets to form two identical rectangles. A stimulus consisted of either one or two of these brackets, lines, or rectangles. Subjects indicated as quickly as possible whether one or two objects occurred. The discriminations between two near brackets and two near lines were more difficult than the discrimination between two near rectangles. A large distance between two objects improved the bracket and line discriminations more than the rectangle discrimination. Single brackets and lines did not result in poorer performance than did single rectangles. These results disconfirm the distance, similarity (including relational similarity), good continuation, location of geometric centers, size, closedness, symmetry, spatial frequency, redundancy, and number of lines component stimulus predictions at least twice. Both the two near brackets and the two near lines produce single gestalts, whereas each remaining 2-object stimulus results in two gestalts. Therefore, gestalts predicted performance better than did component stimuli. Another result was that the 2-object responses were faster than the 1-object responses for far objects.     

Delayed reconfiguration of a non-emotional task set through reactivation of an emotional task set in task switching: an ageing study

ABSTRACT

In our everyday life, we frequently switch between different tasks, a faculty that changes with age. However, it is still not understood how emotion impacts on age-related changes in task switching. Using faces with emotional and neutral expressions, Experiment 1 investigated younger (n?=?29; 18–38 years old) and older adults’ (n?=?32; 61–80 years old) ability to switch between an emotional and a non-emotional task (i.e. responding to the face's expression vs. age). In Experiment 2, younger and older adults also viewed emotional and neutral faces, but switched between two non-emotional tasks (i.e. responding to the face's age vs. gender). Data from Experiment 1 demonstrated that switching from an emotional to a non-emotional task was slower when the expression of the new face was emotional rather than neutral. This impairment was observed in both age groups. In contrast, Experiment 2 revealed that neither younger nor older adults were affected by block-wise irrelevant emotion when switching between two non-emotional tasks. Overall, the findings suggest that task-irrelevant emotion can impair task switching through reactivation of the competing emotional task set. They also suggest that this effect and the ability to shield task-switching performance from block-wise irrelevant emotion are preserved in ageing.     

The role of external cues for endogenous advance reconfiguration in task switching

Most studies of task-set switching rely on cuing paradigms, in which external cues indicate the upcoming task. The present study used an entirely predictable task sequence in a variant of the alternating-runs paradigm of Rogers and Monsell (1995). Preparation effects with purely internal memory cues were compared with those in another experimental group with additional external cues presented prior to the stimulus. External cues led to strongly reduced shift costs with prolonged preparation time. However, this effect was much smaller with internal cues only. To account for this differential effect of preparation time as a function of cue type, it is suggested that internal cues select the next task set, which is sufficient to perform the task. External cues additionally facilitate preparatory retrieval of task-specific stimulus-response rules. This account may also explain why incidental task-sequence learning based on internal cues did not reduce shift costs.     

Preference gives more consistent judgments than oddity only if the task can be modeled as forced choice

Earlier data showed that subjects presented with two samples of distilled water and one of tap water were significantly more consistent in choosing the tap water as preferred than in identifying it as the odd sample in the set. The results were sometimes interpreted as demonstrating greater sensitivity for hedonic judgments than for oddity judgments. They are now shown to be explained by the statistical properties of the decision rules followed in different judgment tasks. In a new expriment, oddity and preference judgments were obtained in a replication of the original task with extra conditions. In two of the new conditions, the decision structure of a preference task was the same as that for the oddity task; in these conditions, performance was no better than with explicit oddity responses. The Thurstone-Ura model of triangle judgments proposed by Frijters predicts the results as an outcome of the greater statistical power of three-alternative forced choice tests compared with triangular tests. An excellent fit to all the data is given by a model wherein all subjects have the samed′ for the difference between the water types but 25% of them prefer distilled water to tap water.     

Women are more sensitive than men to prior trial events on the Stop‐signal task

Sexual dimorphism in the brain and cognition is a topic of widespread interest. Many studies of sex differences have focused on visuospatial and verbal abilities, but few studies have investigated sex differences in executive functions. We examined two key components of executive function – response inhibition and response monitoring – in healthy men (n = 285) and women (n = 346) performing the Stop‐signal task. In this task, participants are required to make a key press to a stimulus, unless a tone is presented at some delay following the initial stimulus presentation; on these infrequent trials, participants are instructed to inhibit their planned response. Response inhibition was assessed with an estimate of the latency needed to inhibit a response (stop‐signal reaction time), and response monitoring was measured by calculating the degree to which participants adjusted their reaction times based on the immediately preceding trial (e.g., speeding following correct trials and slowing following errors). There were no sex differences in overall accuracy or response inhibition, but women showed greater sensitivity to trial history. Women sped up more than men following correct ‘Go’ trials, and slowed down more than men following errors. These small but statistically significant effects (Cohen's d = 0.25–0.3) suggest more flexible adjustments in speed–accuracy trade‐offs in women and greater cognitive flexibility associated with the responsive control of action.     

Verbal representation in task order control: An examination with transition and task cues in random task switching

Recent task-switching studies in which a predictable task sequence has been used have indicated that verbal representation contributes to the control of task order information. The present study focused on the role of verbal representation in sequential task decisions, which are an important part of task order control, and examined the effects of articulatory suppression in a random-task-cuing paradigm with two different types of cues presented just before the presentation of a stimulus: a transition cue and a task cue. The former cue provided information only about switching or repeating the task, whereas the latter was associated directly with the identity of the task (i.e., indicating a parity or a magnitude task). In Experiment 1, in which transition cues guided task sequences, articulatory suppression impaired performance in both repetition and switch trials, thereby increasing the mixing costs. In Experiment 2, in which a task cue, rather than a transition cue, was presented to examine the influence of a cue-decoding process, articulatory suppression had no specific effect on task performance. Experiment 3, in which the transition cue and the task cue were randomly presented in the same block to equalize the memory load and task strategy for the two types of cues, confirmed that articulatory suppression significantly increased the mixing costs only in transition cue trials. The results from the three experiments indicated that the use of verbal representation is effective in sequential task decision—that is, in selecting a task set on the basis of transient task order information in both repetition and switch trials.     

A switch in task affects priming of pop-out: evidence for the role of episodes

Maljkovic and Nakayama (Memory & Cognition, 22(6), 655-678, 1994) demonstrated that response times decrease in a pop-out search task when target-defining features repeat from one trial to the next. This priming of pop-out (PoP) effect has been explained by some researchers as reflecting low-level modulations in attentional control settings Lee, Mozer, and Vecera (Attention, Perception, & Psychophysics, 71(5), 1059-1071, 2009). The present experiments tested whether a shift in higher order task requirements from trial n - 1 to trial n alters PoP effects. The results of Experiments 1 and 2 demonstrated that a switch in task significantly modulated PoP effects when shape was the relevant pop-out dimension. Experiment 3 failed to show significant modulation of PoP as a function of task switch when the pop-out dimension was color, but the findings of Experiment 4 did show modulation of PoP for color when the relative salience of target and distractors was high. Together, the results strongly support the view that PoP effects can be sensitive to a switch in task, a result consistent with the view that PoP effects are modulated by trial-to-trial episodic integration processes.     

Something more than the 'Something more than interpretation' is needed: A comment on the paper by the Process of Change Study Group

A critique is offered of the paper on non-interpretive mechanisms in psychoanalytic therapy by the Process of Change Study Group (Stern et al., 1998a). The attention paid to procedural learning and to the need to attend to implicit relational knowledge is welcomed but a number of the group's assumptions are questioned. In particular, it is argued that the differences between mother-infant and therapist-patient relationships are inadequately considered, that the polarisation of non-symbolic and verbal memory is unhelpful and that the separation of the therapy relationship into three strands is problematic. The assumption that pursuing the goal of intersubjective understanding is in itself therapeutic is questioned. It is suggested that the recognition of the importance of implicit relational knowledge calls for a wider reappraisal of important aspects of theory and practice and that direct means of making such knowledge explicit should be considered.     

Sunk cost: pigeons (Columba livia), too, show bias to complete a task rather than shift to another

The sunk cost effect involves the bias to stay with an alternative because one has already invested resources, even when there is a better alternative available. In a series of experiments, at various points during a 30-peck requirement, pigeons (Columba livia) could choose between completing the response requirement (at a different location in Experiment 1 or the same location in Experiments 3 and 4) and switching to a constant number of pecks. In three experiments, the pigeons showed a bias to complete the pecks already started, even when that required more pecking. We also demonstrated that the bias depended on the initial investment and was not produced merely because the pigeons preferred a variable alternative over a fixed alternative. The deviation from optimal choice suggests that pigeons show a bias similar to the sunk cost effect in humans.     

Family well-being is valued more than personal well-being: A four-country study

Well-being is recognized as a fundamental human goal and a universal human aspiration. However, some cross-country studies suggest that the desirability of the most often studied concept of well-being—personal life satisfaction—varies across countries, and we know little about the desirability of other types of well-being. Extending this novel area of research, we argue that focusing on the family (as compared to the individual) as the subject of well-being may be another important distinction in how well-being is conceptualized and valued. With data collected in four countries that tend to occupy different positions in rankings of personal life satisfaction (i.e., Canada, Colombia, Japan, and Poland), we document that, irrespective of cultural context, family well-being is valued over personal well-being. These findings suggest that policy makers and scientists may need to pay more attention to family well-being than they currently do.