Altmann’s task-switching bibliography, last updated 11-27-16. Please send email if links or files aren't cooperating.


Altmann, E. M. (2014). The extended runs procedure and restart cost. In J. Grange and G. Houghton (Eds.), Task switching and cognitive control (pp. 101-116).  New York: Oxford.

Task-switching procedures provides a means to study the interplay between goal-directedness and cognitive flexibility at a fine temporal grain. Most such procedures cue the current task perceptually on all trials, which means that processes related to this cue factor into behavioral measures on all trials. The extended-runs procedure discussed here makes it possible to isolate stimulus-related processes and the role of episodic memory for the current task. In this procedure, participants perform runs of trials governed by the same task, with the (randomly selected) task cue presented only at the start of the run and then withdrawn. This chapter briefly reviews empirical studies involving this procedure, and theoretical work suggesting that memory-based cognitive control is in fact the general case and thus that results from the extended-runs procedure can be taken to generalize to explicit cuing and alternating runs.

Full text (pdf).


Altmann, E. M. (2013). Fine-grain episodic memory processes in cognitive control. Zeitschrift für Psychologie, 221, 23-32.  (Special issue: Task switching.)

Previous task-switching research raises a question concerning the role of episodic memory processes in cognitive control. The question is framed by the contrast between two procedures, explicit cuing and randomized runs, one of which presents a task cue perceptually on every trial and the other of which involves uncued trials. The present study compares performance across these procedures. Performance errors sensitive to errors in focusing on the correct task were higher under explicit-cuing conditions than under randomized-runs conditions, consistent with a high level of proactive interference from old task information. The results support an account in which control codes stored in episodic memory play an integral role in cognitive control, even under conditions in which all information needed for performance is perceptually available.

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Schroder, H. S., Moran, T. P., Moser, J. S., & Altmann, E. M. (2012).  When the rules are reversed: Action-monitoring consequences of reversing stimulus-response mappings.  Cognitive, Affective, & Behavioral Neuroscience, 12, 629-643.

 

How does switching tasks affect our ability to monitor and adapt our behavior? Largely independent lines of research have examined how individuals monitor their actions and adjust to errors, on the one hand, and how they are able to switch between two or more tasks, on the other. Few studies, however, have explored how these two aspects of cognitive–behavioral flexibility interact. That is, how individuals monitor their actions when task rules are switched remains unknown. The present study sought to address this question by examining the action-monitoring consequences of response switching—a form of task switch- ing that involves switching the response that is associated with a particular stimulus. We recorded event-related brain potentials (ERPs) while participants performed a modified letter flanker task in which the stimulus–response (S–R) mappings were reversed between blocks. Specifically, we examined three ERPs—the N2, the error-related negativity (ERN), and the error positivity (Pe)—that have been closely associated with action monitoring. The findings revealed that S–R reversal blocks were associated with dynamic alterations of action-monitoring brain activity: the N2 and ERN were enhanced, whereas the Pe was reduced. Moreover, participants were less likely to adapt their poster- ror behavior in S–R reversal blocks. Taken together, these data suggest that response switching results in early enhancements of effortful control mechanisms (N2 and ERN) at the expense of reductions in later response evalu- ation processes (Pe). Thus, when rules change, our attempts at control are accompanied by less attention to our actions.

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Altmann, E. M. (2011). Testing probability matching and episodic retrieval accounts of response repetition effects in task switching.  Journal of Experimental Psychology: Learning, Memory, and Cognition, 37, 935-951.

 

This study takes inventory of available evidence on response repetition (RR) effects in task switching, in particular the evidence for RR cost when the task switches. The review reveals that relatively few task-switching studies in which RR effects were addressed have shown statistical support for RR cost, and that almost all are affected by 1 of 2 potential artifacts, either a response bias caused by disallowing stimulus repetitions or the effect of including stimulus repetitions in data analysis. New results with these factors controlled support an episodic retrieval model in which features of the retrieved trace, including the stimulus but also the task, task cue, and response, facilitate or interfere with performance depending on whether they match or mismatch the current processing context.

Full text (pdf). 


Altmann, E. M. & Gray, W. D. (2008).  An integrated model of cognitive control in task switching. Psychological Review, 115, 602-639.

A model of cognitive control in task switching is developed in which controlled performance depends on the system maintaining access to a code in episodic memory representing the most recently cued task.  The main constraint on access to the current task code is proactive interference from old task codes. This interference and the mechanisms that contend with it reproduce a wide range of behavioral phenomena when simulated, including well-known task-switching effects, such as latency and error switch costs, and effects on which other theories are silent, such as with-run slowing and within-run error increase. The model generalizes across multiple task-switching procedures, suggesting that episodic task codes play an important role in keeping the cognitive system focused under a variety of performance constraints.

Full text (pdf). Model code and supporting materials are here. 


Altmann, E. M. (2007). Cue-independent task-specific representations in task switching: Evidence from backward inhibition. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 892-899.

The compound-cue model of cognitive control in task switching explains switch cost in terms of a switch of task cues rather than a switch of tasks. The present study asks whether the model generalizes to lag-2 repetition cost (also known as backward inhibition), a related effect in which the switch from B to A in ABA task sequences is costlier than the same switch in CBA task sequences. The model suggests that lag-2 repetition cost should be absent from A'BA task sequences, where A' and A are different cues for the same task. The cost is robust on such sequences, suggesting that cue-independent, task-specific representations are necessary to explain task-switching performance, and that the compound-cue model has limited explanatory power.

Full text (pdf).


Altmann, E. M. (2007). Comparing switch costs: Alternating runs and explicit cuing. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33, 475-483.

The task-switching literature routinely conflates different operational definitions of switch cost, its predominant behavioral measure. This article is an attempt to draw attention to differences between the two most common definitions, alternating-runs switch cost (ARS) and explicit-cuing switch cost (ECS). ARS appears to include both the costs of switching tasks and switch-independent costs specific to the first trial of a run, with the implication that it should generally be larger than ECS, but worse is that the alternating-runs procedure does not allow these costs to be separated. New data are presented to make these issues concrete, existing data are surveyed for evidence that ARS is larger than ECS, and implications of conflating these measures are examined for existing theoretical constructs.

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Altmann, E. M. (2006). Task switching is not cue switching. Psychonomic Bulletin & Review, 13, 1016-1022.

With the aim of reducing cognitive control in task switching to simpler processes, researchers have proposed in a series of recent studies that there is little more to switching tasks than switching cues.  The present study addresses three questions concerning this reduction hypothesis.  First, does switching cues account for all relevant variance associated with switching tasks? Second, how well does this hypothesis generalize beyond the experimental procedure from which it was developed?  Third, how well does this new procedure preserve relevant measures like task-switch cost?  The answers (no, not very, not very) suggest that task switching does not reduce to cue switching.

Full text (pdf),  data and fits (Excel) 


Altmann, E. M. (2005). Repetition priming in task switching: Do the benefits dissipate? Psychonomic Bulletin & Review, 12, 535-540.

In task-switching research, one process that has been implicated as a possible source of switch cost is repetition priming.  Four experiments examine 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 subjects, producing the standard RCI effect on switch cost.  In Experiments 3 and 4, RCI was manipulated between subjects, 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 like 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 appears to be more stable over time than previously thought.

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Altmann, E. M. (2004). Advance preparation in task switching: What work is being done? Psychological Science, 15, 616-622.

The preparation effect in task switching is usually interpreted to mean that a switching process makes use of the interval between task-cue onset and trial-stimulus onset (the cue-stimulus interval, or CSI) to accomplish some of its work ahead of time.  This study undermines the empirical basis for this interpretation and suggests that task activation, not task switching, is the functional process in cognitive control.  Experiments 1 and 2 use an explicit cueing paradigm, and Experiments 3 and 4 use a variation in which the trial after a task cue is followed by several cueless trials, requiring retention of the cue in memory.  Experiments 1 and 3 replicate the preparation effect on switch cost, and Experiments 2 and 4 show that this effect vanishes when CSI is manipulated between subjects, leaving only a main effect of CSI when the task cue is a memory load.

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Altmann, E. M. (2004). The preparation effect in task switching: Carryover of SOA. Memory & Cognition, 32, 153-163.

A common finding in task switching studies is switch preparation (commonly known as the preparation effect), in which a longer interval between task cue and trial stimulus (i.e., a longer stimulus onset asynchrony, or SOA) reduces the cost of switching to a different task. Three experiments link switch preparation to within-subject manipulations of SOA. In Experiment 1, SOA was randomized within subjects, producing switch preparation that was more pronounced when the SOA switched from the previous trial than when the SOA repeated. In Experiment 2, SOA was blocked within subjects, producing switch preparation but not on the first block of trials. In Experiment 3, SOA was manipulated between subjects with sufficient statistical power to detect switch preparation, but the effect was absent. The results favor an encoding view of cognitive control, but show at least that any putative switching mechanism reacts lazily when exposed to only one SOA.

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Altmann, E. M. (2003). Task switching and the pied homunculus: Where are we being led? Trends in Cognitive Sciences, 7, 340-341.

Letter. 

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Altmann, E. M. (2002).  Functional decay of memory for tasks. Psychological Research, 66, 287-297.

Correct performance often depends on remembering the task one has been instructed to do. When the task periodically changes, memory for the current task must decay (lose activation) to prevent it from interfering with memory for the next task when that is encoded. Three task-switching experiments examine this decay process. Each shows within-run slowing, a performance decline occurring as memory for the current task decays. In experiment 1, slowing is attenuated when memory for the task is optional, suggesting that memory is indeed causal. Experiment 2 finds slowing despite a flat hazard rate for task instructions, suggesting that slowing is not an artifact of instruction anticipation. Experiment 3 finds slowing in the familiar alternating-runs paradigm (Rogers & Monsell, 1995), suggesting that it may lurk elsewhere. A process model of activation explains within-run slowing and relates it to switch cost and "restart cost" (Allport & Wylie, 2000) in functional terms.

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Altmann, E. M. & Gray, W. D. (2002).  Forgetting to remember: The functional relationship of decay and interference. Psychological Science, 13, 27-33.

Functional decay theory proposes that decay and interference, historically viewed as competing accounts of forgetting, are instead functionally related. The theory posits (a) that when an attribute must be updated frequently in memory, its current value decays to prevent interference with later values, and (b) the decay rate adapts to the rate of memory updates. Behavioral predictions of the theory were tested in a task-switching paradigm in which memory for the current task had to be updated every few seconds, hundreds of times. RT and error both increased gradually between updates, reflecting decay of memory for the current task. This performance decline was slower when updates were less frequent, reflecting a decrease in the decay rate following a decrease in the update rate. A candidate mechanism for controlled decay is proposed, the data are reconciled with practice effects, and implications are discussed for models of executive control.

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