Abstract
During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. It has been shown that cognitive control can be triggered proactively by contextual cues that predict conflict. Here, we investigated whether a pretrial preparation interval could serve as such a cue. This would show that the temporal contingencies embedded in the task can be used to anticipate upcoming conflict. To this end, we recorded electroencephalography (EEG) from 30 human subjects while they performed a version of a Simon task in which the duration of a fixation cross between trials predicted whether the next trial would contain response conflict. Both their behavior and EEG activity showed a consistent but unexpected pattern of results: The conflict effect (increased reaction times and decreased accuracy on conflict as compared to nonconflict trials) was stronger when conflict was cued, and this was associated with stronger conflict-related midfrontal theta activity and functional connectivity. Interestingly, intervals that predicted conflict did show a pretarget increase in midfrontal theta power. These findings suggest that temporally guided expectations of conflict do heighten conflict anticipation, but also lead to less efficiently applied reactive control. We further explored this post-hoc interpretation by means of three behavioral follow-up experiments, in which we used nontemporal cues, semantically informative cues, and neutral cues. Together, this body of results suggests that the counterintuitive cost of conflict cueing may not be uniquely related to the temporal domain, but may instead be related to the implicitness and validity of the cue.
Highlights
During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity
2000), where the medial frontal cortex (MFC) is thought to signal the need for control in response to challenging situations (Alexander & Brown, 2011; Botvinick, Cohen, & Carter, 2004; Ito, Stuphorn, Brown, & Schall, 2003), which is communicated to the dorsolateral prefrontal cortex (DLPFC; MacDonald, Cohen, Stenger, & Carter, 2000)
This replicates earlier findings of the congruency sequence effect (Egner, Ely, & Grinband, 2010; Gratton et al, 1992). Both the conflict effect and the conflict sequence effect were present in accuracy, as well: Subjects performed worse on incongruent than on congruent trials [F(1, 28) = 8.74, p = .006], and this decrease in performance was attenuated when the previous trial was incongruent [F(1, 28) = 11.88, p = .002]
Summary
During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. Intervals that predicted conflict did show a pretarget increase in midfrontal theta power These findings suggest that temporally guided expectations of conflict do heighten conflict anticipation, and lead to less efficiently applied reactive control. K. Miller, 2000), where the medial frontal cortex (MFC) is thought to signal the need for control in response to challenging situations (Alexander & Brown, 2011; Botvinick, Cohen, & Carter, 2004; Ito, Stuphorn, Brown, & Schall, 2003), which is communicated to the dorsolateral prefrontal cortex (DLPFC; MacDonald, Cohen, Stenger, & Carter, 2000) Both of these regions exert top-down influence over lower, task-related sensorimotor processing These trial-to-trial fluctuations in behavioral conflict effects have been shown to covary with trial-to-trial variability in midfrontal theta activity (Cohen & Cavanagh, 2011)
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