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43
Task switching and novelty processing activate a common neural network for cognitive control
, 2006
"... & The abrupt onset of a novel event captures attention away from, and disrupts, ongoing task performance. Less obvious is that intentional task switching compares with novelty-induced behavioral distraction. Here we explore the hypothesis that intentional task switching and attentional capture b ..."
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Cited by 33 (9 self)
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& The abrupt onset of a novel event captures attention away from, and disrupts, ongoing task performance. Less obvious is that intentional task switching compares with novelty-induced behavioral distraction. Here we explore the hypothesis that intentional task switching and attentional capture by a novel distracter both activate a common neural network involved in processing contextual novelty [Barcelo, F., Periáñez, J. A., & Knight, R. T. Think differently: A brain orienting response to task novelty. NeuroReport, 13, 1887–1892, 2002.]. Eventrelated potentials were recorded in two task-cueing paradigms while 16 subjects sorted cards following either two (color or shape; two-task condition) or three (color, shape, or number; three-task condition) rules of action. Each card was preceded by a familiar tone cueing the subject either to switch or to
Who comes first? The role of the prefrontal and parietal cortex in cognitive control
"... & Cognitive control processes enable us to adjust our behavior to changing environmental demands. Although neuropsychological studies suggest that the critical cortical region for cognitive control is the prefrontal cortex, neuro-imaging studies have emphasized the interplay of prefrontal and pa ..."
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Cited by 13 (0 self)
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& Cognitive control processes enable us to adjust our behavior to changing environmental demands. Although neuropsychological studies suggest that the critical cortical region for cognitive control is the prefrontal cortex, neuro-imaging studies have emphasized the interplay of prefrontal and parietal cortices. This raises the fundamental question about the different contributions of prefrontal and parietal areas in cognitive control. It was assumed that the prefrontal cortex biases processing in posterior brain regions. This as-sumption leads to the hypothesis that neural activity in the prefrontal cortex should precede parietal activity in cognitive control. The present study tested this assumption by com-bining results from functional magnetic resonance imaging (fMRI) providing high spatial resolution and event-related potentials (ERPs) to gain high temporal resolution. We collected ERP data using a modified task-switching paradigm. In this paradigm, a situation where the same task was in-dicated by two different cues was compared with a situation where two cues indicated different tasks. Only the latter condition required updating of the task set. Task-set updating was associated with a midline negative ERP deflection peaking around 470 msec. We placed dipoles in regions activated in a previous fMRI study that used the same paradigm (left inferior frontal junction, right inferior frontal gyrus, right parietal cortex) and fitted their directions and magnitudes to the ERP effect. The frontal dipoles contributed to the ERP effect earlier than the parietal dipole, providing support for the view that the prefrontal cortex is involved in updating of general task representations and biases relevant stimulus–response associ-ations in the parietal cortex. &
Neurophysiological signature of effective anticipatory task-set control: a task-switching investigation
- Eur J Neurosci
, 2008
"... Changing between cognitive tasks requires a reorganization of cognitive processes. Behavioural evidence suggests this can occur in advance of the stimulus. However, the existence or detectability of an anticipatory task-set reconfiguration process remains controversial, in part because several neuro ..."
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Cited by 12 (0 self)
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Changing between cognitive tasks requires a reorganization of cognitive processes. Behavioural evidence suggests this can occur in advance of the stimulus. However, the existence or detectability of an anticipatory task-set reconfiguration process remains controversial, in part because several neuroimaging studies have not detected extra brain activity during preparation for a task switch relative to a task repeat. In contrast, electrophysiological studies have identified potential correlates of preparation for a task switch, but their interpretation is hindered by the scarcity of evidence on their relationship to performance. We aimed to: (i) identify the brain potential(s) reflecting effective preparation for a task-switch in a task-cuing paradigm that shows clear behavioural evidence for advance preparation, and (ii) characterize this activity by means of temporal segmentation and source analysis. Our results show that when advance preparation was effective (as indicated by fast responses), a protracted switch-related component, manifesting itself as widespread posterior positivity and concurrent right anterior negativity, preceded stimulus onset for 300 ms, with sources primarily in the left lateral frontal, right inferior frontal and temporal cortices. When advance preparation was ineffective (as implied by slow responses), or made impossible by a short cue–stimulus interval (CSI), a similar component, with lateral prefrontal generators, peaked 300 ms poststimulus. The protracted prestimulus component (which we show to be distinct from P3 or contingent negative variation, CNV) also correlated over subjects with a behavioural measure of preparation. Furthermore, its differential lateralization for word and picture cues was consistent with a role for verbal self-instruction in preparatory task-set reconfiguration.
Distinct neurophysiological mechanisms mediate mixing costs and switch costs
- Journal of Cognitive Neuroscience
, 2008
"... & Using event-related potentials (ERPs), we investigated the neural response associated with preparing to switch from one task to another. We used a cued task-switching paradigm in which the interval between the cue and the imperative stim-ulus was varied. The difference between response time (R ..."
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Cited by 7 (0 self)
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& Using event-related potentials (ERPs), we investigated the neural response associated with preparing to switch from one task to another. We used a cued task-switching paradigm in which the interval between the cue and the imperative stim-ulus was varied. The difference between response time (RT) to trials on which the task switched and trials on which the task repeated (switch cost) decreased as the interval between cue and target (CTI) was increased, demonstrating that sub-jects used the CTI to prepare for the forthcoming task. How-ever, the RT on repeated-task trials in blocks during which the task could switch (mixed-task blocks) were never as short as RTs during single-task blocks (mixing cost). This replicates previous research. The ERPs in response to the cue were compared across three conditions: single-task trials, switch trials, and repeat trials. ERP topographic differences were found between single-task trials and mixed-task (switch and repeat) trials at 160 and 310 msec after the cue, indicative of changes in the underlying neural generator configuration as a basis for the mixing cost. In contrast, there were no topographic differences evident between switch and repeat trials during the CTI. Rather, the response of statistically in-distinguishable generator configurations was stronger at 310 msec on switch than on repeat trials. By separating dif-ferences in ERP topography from differences in response strength, these results suggest that a reappraisal of previous research is appropriate. &
A Critical Test of the Failure-to-Engage Theory of Task-Switching
"... When people switch between two tasks, their performance on each is worse than when they perform that task in isolation. This "switch cost" has been extensively studied, and many theories have been proposed to explain it. One influential theory is the "failure to engage" (FTE) the ..."
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Cited by 6 (3 self)
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When people switch between two tasks, their performance on each is worse than when they perform that task in isolation. This "switch cost" has been extensively studied, and many theories have been proposed to explain it. One influential theory is the "failure to engage" (FTE) theory, which posits that observed responses are a mixture of prepared and unprepared response strategies. The probability that participants use prepared processes can be manipulated experimentally, by changing preparation time, for example. The FTE theory is a binary mixture model, and therefore makes a strong prediction about the existence of fixed points in response time distributions. We found evidence contradicting this prediction, using data from 54 participants in a standard task-switching paradigm.
Switch-specific and general preparation map onto different ERP components in a task-switching paradigm. Psychophysiology, 2011; 48(4): 559–568 doi: 10.1111/j.1469-8986.2010.01115.x PMID: 20718932
"... Abstract We examined whether the cue-locked centroparietal positivity is associated with switch-specific or general preparation processes. If this positivity (300-400 ms) indexes switch-specific preparation, faster switch trials associated with smaller RT switch cost should have a larger positivity ..."
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Cited by 6 (2 self)
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Abstract We examined whether the cue-locked centroparietal positivity is associated with switch-specific or general preparation processes. If this positivity (300-400 ms) indexes switch-specific preparation, faster switch trials associated with smaller RT switch cost should have a larger positivity as compared to slower switch trials, but no such association should be evident for repeat trials. We extracted ERP waveforms corresponding to semi-deciles of each participant's RT distribution (i.e., fastest to slowest 5% of trials) for switch and repeat conditions. Consistent with a switch-specific preparation process, centroparietal positivity amplitude was linked to slower RT and larger RT switch cost for switch but not repeat trials. A later pre-target negativity (500-600 ms) was inversely correlated with RT for both switch and repeat trials, consistent with a general anticipatory preparation processes.
Attentional set mixing: Effects on target selection and selective response activation
- Psychophysiology
, 2006
"... Performance is impaired under set mixing conditions that require frequent readjustments of attentional focus over an extended time period. We compared set repetitions within pure blocks (constant focus of attention) to physically identical repetitions within mixed blocks (changing focus of attention ..."
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Cited by 6 (0 self)
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Performance is impaired under set mixing conditions that require frequent readjustments of attentional focus over an extended time period. We compared set repetitions within pure blocks (constant focus of attention) to physically identical repetitions within mixed blocks (changing focus of attention). The aim was to investigate how set mixing affects target selection, indexed by the N2pc component, and selective response activation, indexed by the lateralized readiness potential (LRP). We found that set mixing prolonged the evolution of the N2pc while leaving its onset unaffected. Impaired target selection indicated by the N2pc mixing effect also delayed the start of response planning indexed by an onset delay of the stimulus-locked LRP, explaining one part of the behavioral mixing cost. A larger part of mixing cost could be attributed to a prolonged response planning phase, indexed by an earlier onset of the response-locked LRP.
The BOLD onset transient: identification of novel functional differences in schizophrenia.
- NeuroImage
, 2005
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Electrophysiological evidence for endogenous control of attention in switching between languages in overt picture naming
- J. Cogn. Neurosci
, 2010
"... Abstract ■ Language switching in bilingual speakers requires attentional control to select the appropriate language, for example, in picture naming. Previous language-switch studies used the color of pictures to indicate the required language thereby confounding endogenous and exogenous control. To ..."
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Cited by 3 (0 self)
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Abstract ■ Language switching in bilingual speakers requires attentional control to select the appropriate language, for example, in picture naming. Previous language-switch studies used the color of pictures to indicate the required language thereby confounding endogenous and exogenous control. To investigate endogenous language control, our language cues preceded picture stimuli by 750 msec. Cue-locked event-related potentials (ERPs) were measured while Dutch-English bilingual speakers overtly named pictures. The response language on consecutive trials could be the same (repeat trials) or different (switch trials). Naming latencies were longer on switch than on repeat trials, independent of the response language. Cue-locked ERPs showed an early posterior negativity for switch compared to repeat trials for L2 but not for L1, and a late anterior negativity for switch compared to repeat trials for both languages. The early switch-repeat effect might reflect disengaging from the nontarget native language, whereas the late switch-repeat effect reflects engaging in the target language. Implications for models of bilingual word production are discussed. ■
