Response-cue Interval Research Articles

EXPRESS: Exploring 'phasic' vs. 'tonic' accounts of the effect of switch probability on the auditory attention switch cost.

Task-switching experiments have shown that the 'switch cost' (poorer performance for task switches than for repetitions) is smaller when the probability of a switch is high (e.g., 0.75) than when it is low (e.g., 0.25). Some theoretical accounts explain this effect in terms of top-down control deployed in advance of the task cue ('pre-cue reconfiguration'). We tested such accounts by manipulating the time available before the onset of the cue (the response-cue interval, RCI), reasoning that top-down pre-cue reconfiguration requires time and therefore its effect should increase with RCI. Participants heard a man and a woman simultaneously speaking number words and categorised the number (<5 vs. >5) spoken by the voice specified by a pictorial gender-related cue presented at an RCI of 100 ms or 2200 ms. The target voice switched with a probability of 0.25 or 0.75 (in separate sessions). In Experiment 1 RTs revealed a large effect of switch probability on the switch cost in the short RCI, which did not increase in the long RCI. Errors hinted at such an increase, but it did not receive clear statistical support and was disconfirmed by a direct and better powered replication in Experiment 2, which fully confirmed the RT pattern from Experiment 1. Thus, the effect of switch probability on the switch cost required little/no time following the response to emerge - it was already at full magnitude at a short RCI - challenging accounts that assume 'phasic' deployment of top-down task-set control in advance of the cue.

The persisting influence of unattended auditory information: Negative priming in intentional auditory attention switching.

We studied negative priming (NP) in auditory attention switching. In a cued variant of dichotic listening, two spoken number words were presented, one to each ear, one spoken by a female, and one spoken by a male voice. A visual cue indicated whether the male or female voice was the target. A numerical magnitude judgement of the target number was required. The selection criterion could either switch or repeat across trials, so there were attention switch and repetition trials. Two experiments examined NP (distractor becomes target) and also included a "competitor priming" (CP) condition (target becomes distractor), relative to a "no priming" condition (target and distractor not related to previous trial). In Experiment 1, we investigated the basic priming effects. In Experiment 2, we additionally varied the response-cue interval (RCI; 100 ms vs. 1,900 ms) to examine time-related changes in priming. We found longer response times (RT) for switch trials compared with repetition trials (attention switch costs)-that is, when the internal processing context changed. In addition, we found longer RT for NP trials as well as reduced switch costs in long RCI, suggesting that previously relevant attentional settings dissipate over longer time. However, NP was not influenced by attention switches, and it was also not affected byRCI. Hence, NP in auditory attention switching does not seem strongly context or time sensitive.

Does Task Activation in Task Switching Influence Inhibition or Episodic Interference?

N-2 repetition costs in task switching refer to slower responses to ABA sequences compared to CBA sequences, reflecting the persisting inhibition of task A across the ABA sequence. The magnitude of inhibition is thought to be sensitive to activation levels of interfering tasks. This is supported by larger n-2 repetition costs when the response-cue interval (RCI) is reduced: At short RCIs, a just-performed task is highly active when a new task is required, triggering more inhibition. However, recent work has shown that much of the n-2 repetition cost measures episodic interference, rather than inhibition. The current study addressed whether RCI manipulations influence inhibition or episodic interference. N-2 repetition costs were considerably reduced when episodic interference was controlled. Increasing the RCI led to equivalent reductions in the n-2 repetition cost for inhibition and episodic components of the cost, but for the former, the cost was entirely absent at longer RCIs.

Response-cue interval effects in extended-runs task switching: memory, or monitoring?

This study investigated effects of manipulating the response-cue interval (RCI) in the extended-runs task-switching procedure. In this procedure, a task cue is presented at the start of a run of trials and then withdrawn, such that the task has to be stored in memory to guide performance until the next task cue is presented. The effects of the RCI manipulation were not as predicted by an existing model of memory processes in task switching (Altmann and Gray, Psychol Rev 115:602-639, 2008), suggesting that either the model is incorrect or the RCI manipulation did not have the intended effect. The manipulation did produce a theoretically meaningful pattern, in the form of a main effect on response time that was not accompanied by a similar effect on the error rate. This pattern, which replicated across two experiments, is interpreted here in terms of a process that monitors for the next task cue, with a longer RCI acting as a stronger signal that a cue is about to appear. The results have implications for the human factors of dynamic task environments in which critical events occur unpredictably.

Temporal Distinctiveness in Task Switching: Assessing the Mixture-Distribution Assumption.

In task switching, increasing the response–cue interval has been shown to reduce the switch cost. This has been attributed to a time-based decay process influencing the activation of memory representations of tasks (task-sets). Recently, an alternative account based on interference rather than decay has been successfully applied to this data (Horoufchin et al., 2011a). In this account, variation of the RCI is thought to influence the temporal distinctiveness (TD) of episodic traces in memory, thus affecting their retrieval probability. This can affect performance as retrieval probability influences response time: If retrieval succeeds, responding is fast due to positive priming; if retrieval fails, responding is slow, due to having to perform the task via a slow algorithmic process. This account—and a recent formal model (Grange and Cross, 2015)—makes the strong prediction that all RTs are a mixture of one of two processes: a fast process when retrieval succeeds, and a slow process when retrieval fails. The present paper assesses the evidence for this mixture-distribution assumption in TD data. In a first section, statistical evidence for mixture-distributions is found using the fixed-point property test. In a second section, a mathematical process model with mixture-distributions at its core is fitted to the response time distribution data. Both approaches provide good evidence in support of the mixture-distribution assumption, and thus support temporal distinctiveness accounts of the data.

Can time-based decay explain temporal distinctiveness effects in task switching?

In task switching, extending the response-cue interval (RCI) reduces the switch cost--the detriment to performance when switching compared to repeating tasks. This reduction has been used as evidence for the existence of task-set decay processes. Recently, this has been challenged by the observation of sequential dependencies on the RCI effect: switch cost is only reduced at longer RCIs when the previous trial had a short RCI. This trial-wise variation of RCI is thought to affect the temporal distinctiveness (TD) of a previous task's episodic trace, affecting the probability of its automatic retrieval on the current trial; importantly, TD is thought to be independent of the current trial's RCI. The present study highlights a dependency between the current RCI and TD, and demonstrates that a decay model can reproduce some patterns of data attributed to TD. Further, the decay account makes a strong prediction when TD is held constant: repetition response times should slow as the RCI increases, and switch response times should be facilitated. This prediction was tested via re-analysis of extant data and three experiments. The re-analysis provided some evidence for the decay account, but Experiments 1 and 2 report slowing for task repetition and switch trials, which cannot be explained by a task-set decay process. Experiment 3, which utilized tasks requiring perceptual judgements, showed small evidence for decay. We conclude that the data are largely consistent with the TD account and that the evidence for decay of higher-level task-sets is not convincing.

Tracing the time course of n - 2 repetition costs in task switching.

In order to flexibly adapt to a permanently changing environment, it is necessary to inhibit previously activated but now irrelevant processing pathways. Empirically, this inhibition manifests itself only indirectly in terms of a cost of reengaging a previously inhibited pathway (n - 2 repetition costs). While imaging studies suggest an involvement of the prefrontal cortex in this type of inhibition, it has recently been argued that the underlying processes are implicated not in triggering inhibition, but in overcoming it. To disentangle these processes on a behavioral level, we investigated the time course of inhibition using a cued task switching paradigm. The response-cue interval (between the response of trial n - 1 and the cue of trial n) was varied in five steps to capture its influence on inhibition in a fine-grained manner. The results suggest that the impact of inhibitory processes increases during the first 200-300 ms after the response of the previous trial, reaches its full extent with about 300 ms, and starts to diminish after that. Therefore, future research on the neural correlates of n - 2 repetition costs should employ techniques with a high temporal resolution that are able to capture this presumed time course of inhibitory processes.

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.

Episodic retrieval and decaying inhibition in the competitor-rule suppression phenomenon

The Competitor Rule Suppression (CRS) effect is the performance impairment observed in task switching when the currently relevant task rule is the same rule that had generated a response conflict in the preceding trial. This effect could reflect (a) episodic tagging, in which a competitor rule is retrieved with relative difficulty in subsequent trials or (b) residual active inhibition of the competing rule. In order to help distinguishing between the two accounts, the authors manipulated the Response–Cue Interval (RCI), which may influence both processes. CRS increased with increasing temporal distinctiveness between the previous and current episode (operationalized by the ratio of the current RCI to the previous RCI, RCI/pRCI), thus supporting episodic tagging. CRS additionally decreased numerically with increasing RCI even when the RCI/pRCI ratio was fixed, thereby providing suggestive support for the decay account.

Preserved and impaired task‐switching abilities in non‐demented patients with Parkinson's disease

Existing studies on task switching in Parkinson's disease (PD) patients have led to somewhat different results. In particular, it is unclear whether PD patients have a deficit in attentional control. In this study, we assessed task-switching abilities in samples of non-demented PD patients and elderly controls. We used a paradigm in which there was a random task sequence and the task was cued in every trial. This allowed the investigation of both task-set reconfiguration and task-set dissipation. In terms of the proportion of errors made, the patients showed increased switch cost and congruency effects. For reaction times, PD patients showed enlarged congruency effects on switch trials, specifically in the condition in which we used a short constant response-cue interval (RCI). Nevertheless, in a similar fashion to older controls, the patients showed reductions in reaction time switch cost from a short to a long cue-target interval (CTI) and from a short to a long RCI. While these latter findings, respectively, suggest unimpaired task preparation and task dissipation on correct trials in the PD patients, the overall results show that they have a deficit in biasing and selecting currently relevant task sets and more generally argue in favour of a failure of attentional control in PD.

Generic cognitive adaptations to task interference in task switching

The present study investigated how the activation of previous tasks interferes with the execution of future tasks as a result of temporal manipulations. Color and shape matching tasks were organized in runs of two trials each. The tasks were specified by a cue presented before a task run, cueing only the first trials of each run. Response times (RTs) and error rates were measured for task switching and task repetition conditions. Task interference was varied as a function of response-cue interval (RCI of 300 and 900 ms), that is, the interval between the task runs. Keeping the response–stimulus interval within the task runs constant at 300 ms allowed the disentangling of the direct effects of RCI manipulation on performance (first trials) from the general effects on performance (both trials in the run). The data showed similar performance improvement due to RCI increase on both trials in the task run. Furthermore, increasing RCI improved both switch and repetition performance to a similar extent. Together, our findings provide further evidence for accounts stressing generic effects of proactive task interference in task switching.

Repetition priming in task switching: Do the benefits dissipate?

In task-switching research, one process that has been implicated as a possible source of switch cost is repetition priming. In four experiments, an examination was made of the claim that repetition priming dissipates over the interval between trials and thereby causes switch cost to decrease with increases in the response-cue interval (RCI). In Experiments 1 and 2, RCI was manipulated within participants, producing the standard RCI effect on switch cost. In Experiments 3 and 4, RCI was manipulated between participants and had no effect on switch cost. The role of experimental design and the mixed pattern of effects on switch and repeat trials in Experiments 1 and 2 suggest that a passive architectural process such as priming dissipation is not responsible for the RCI effect on switch cost. Repetition priming may still be responsible for some or all of switch cost, but it appears to be more stable over time than was previously thought.

Inhibition of response mode in task switching.

Task inhibition was explored in two experiments that employed a paradigm in which participants switched among three tasks. Two tasks required manual choice responses based on numerical judgment (parity or magnitude), whereas a third task required an unconditional double-press of both response keys. Both experiments showed that switching to a just-abandoned task (n-2 task repetition) generally leads to a performance cost relative to switching to another task. Specifically, this task inhibition effect also occurred for the double-press task, suggesting inhibition of response mode. Prolonging the task-cuing interval showed that advance task preparation reduced only inhibition of the double-press task but not of the choice tasks (Experiment 1). Prolonging the response-cue interval led to a decrease of the inhibition effect in all tasks (Experiment 2), suggesting a time-based release of task inhibition. Together, the experiments support the notion of a response-related component of task inhibition.

Inhibition of Response Mode in Task Switching

Inhibition of Response Mode in Task Switching

Automatic and intentional activation of task sets.

Four experiments examined automatic and intentional activation of task sets in a switching paradigm. Experiment 1 demonstrated incidental task sequence learning that was not accompanied by verbalizable task sequence knowledge. This learning did not affect task shift cost and may be attributed to automatic task-set activation. In Experiment 2, both shift cost and learning effect increased when the response-cue interval was short, indicating the influence of residual, persisting activation of the preceding task set. In Experiment 3, learning disappeared with a long cue-stimulus interval (CSI), which resulted in a strong preparation effect. This preparation, however, reduced reaction time level but was not specific to task shifts. Finally, Experiment 4 showed that a within-subject C

Component Processes in Task Switching

Participants switched between two randomly ordered, two-choice reaction-time (RT) tasks, where an instructional cue preceded the target stimulus and indicated which task to execute. Task-switching cost dissipated passively while the participants waited for the instructional cue in order to know which task to execute (during the Response–Cue Interval). Switching cost was sharply reduced, but not abolished, when the participants actively prepared for the task switch in response to the instructional cue (during the Cue–Target Interval). The preparation for a task switch has shown not to be a by-product of general preparation by phasic alertness or predicting target onset. It is suggested that task-switching cost has at least three components reflecting (1) the passive dissipation of the previous task set, (2) the preparation of the new task set, and (3) a residual component.