Cognitive Dynamics Lab


The question whether during selection of one thought, competing thoughts are actively inhibited is a hotly debated issue in cognitive science, with far-reaching theoretical and practical consequences. Over the last years, our goal has been to come up with an unambiguous empirical indicator of inhibition.

In the past, such clear evidence has been hard to come by, as "inhibitory" patterns of results can often be explained in terms of non-inhibitory processes. In our lab, we have come up with a way of assessing inhibition between task sets (Mayr & Keele, 2000). We compare situations in which people need to switch back to a task that they had disengaged from very recently (the color task in the figure) to situations where the switch goes to a less recently abandoned task (the orientation task in the figure). Switching back to a recently abandoned task costs extra time, supposedly because it is still inhibited. This so-called backward-inhibition cost seems to be relatively immune against alternative, non-inhibitory explanations (Mayr, 2002). It also provides a tool for examining cognitive and neural characteristics of inhibition. For example, Mayr, Diedrichsen, Ivry, & Keele (2006) showed that left- and right prefrontal patients had very different types of task-switching problems.

Specifically, right prefrontal patients (see Figure) showed no task-set inhibition. We also recently reported results suggesting that inhibition of the immediate past may serve the function of clearing the slate for making random, unpredictable choices, a skill that can come very handy in real-life competitive situations (Mayr & Bell, 2006). In ongoing work, we are interested in showing a more direct link between inhibition and "free choice" and we are trying to establish an empirical distinction between two theoretically distinct types of inhibition: executive and associative.

Mayr, U., & Keele, S. (2000). Changing internal constraints on action: The role of backward inhibition. Journal of Experimental Psychology: General, 129, 4-26. PDF

Mayr, U. (2001). Age differences in the selection of mental sets: The role of inhibition, stimulus ambiguity, and response-set overlap. Psychology and Aging, 16, 96-109. PDF.

Mayr, U. (2002). Inhibition of action rules. Psychonomic Bulletin and Review, 9, 93-99. PDF

Mayr, U., Diedrichsen, J., Ivry, R., & Keele, S. (2006). Dissociating task-set selection from task-set inhibition in prefrontal cortex. Journal of Cognitive Neuroscience , 18, 14-21.PDF

Mayr, U. (in press). Inhibition of task sets. In D.S. Gorfein & C.M. MacLeod (Eds.). Inhibition in Cognition. APA Books: Washington DC. PDF

Mayr, U., & Bell, T. (2006). On how to be unpredictable: Evidence from the voluntary task-switching paradigm. Psychological Science , 17, 774-780. PDF

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