Cognitive flexibility and N2/P3 event-related brain potentials

Figure 1. A graphical outline of the eligibility framework, which has its roots in associative binding theories of task switching15. Square brackets indicate manipulated variables, with [] denoting that their eligibility on trial t was controlled (eligible, ineligible). t = trial number; T = task set; rS = task-relevant stimulus feature; iS = task-irrelevant stimulus feature; R = response; RR = response repetition. Stimulus-related switch costs: On the depicted switch trial, Tt-1 exerts carry-over interference on the execution of Tt (represented by the circular endpoint of the red dashed line) due to the reenactment (represented by the horizontal blue dashed line) of the stimulus-set binding that took place on trial t-1 (represented by the vertical blue dashed line). Eligible task-irrelevant stimulus features reenact stimulus-set bindings via the iSt = rSt-1 equality, increasing carry-over interference exerted by Tt-1. Response-related switch costs: On the depicted switch trial, Tt-1 exerts carry-over interference on the execution of Tt due to the reenactment (represented by the horizontal orange dashed line) of the response-set binding that took place on trial t-1 (represented by the…

Figure 2. An exemplified trial on the Cued Card Matching Task (CCMT). Response and task cues were followed by targets. Three reference cards and one response card constituted the target, and both types of cards depicted coloured geometrical shapes. The task required matching the response card against the three horizontally aligned reference cards. On each trial, two tasks were possible: colour or shape. In our example trial, the red star matches the red triangle (identical with regard to colour), and it matches the yellow star (identical with regard to shape), but there is no match between the red star and the green diamond (hence the middle reference card is not viable for responding). The correct response to the cued task SHAPE is STAR, to be indicated by choosing the right reference card. The response to the irrelevant (competitor) task COLOR would be RED, to-be-indicated by choosing the left reference card. The two response cues 7 and 8 render both the middle (non-viable) and the right (shape task) reference card/response eligible. The omitted response cue 6 renders the left (colour task) reference card/response ineligible. Hence, the depicted trial exemplifies the ineligible…

Figure 3. Three exemplified consecutive trials on the Cued Card Matching Task (CCMT). Two tasks are possible on each trial, that is, colour and shape. Trial n shows an “eligible competitor task” (CTe), “ineligible previous response” (PRi) trial. Here, the correct response is DIAMOND, hence the middle reference card (7 key). Given the two response cues on trial n, the irrelevant task (colour) remains eligible (RED, left response card). In contrast, the previous response (i.e., the 8 key on trial n – 1) is made ineligible by the response cues. Trial n – 1 shows an “ineligible competitor task” (CTi), “eligible previous response” (PRe) trial. Here, the correct response is STAR, hence the right reference card (8 key). Given the two response cues on trial n – 1, the irrelevant task (colour) is made ineligible (GREEN, middle response card) by the response cues. In contrast, the previous response remains eligible (i.e., the 6 key on trial n – 2). CTi = competitor task ineligible; CTe = competitor task eligible; PRe = previous response eligible; PRi = previous response ineligible.

Figure 4. Mean RTs, PE and LISAS (a.u., arbitrary units) separately for task-switch and task-repeat trials, and across CTE (ineligible, eligible) and Response Variability (PRi | response alternation, PRe | response alternation, PRe | response repetition). Error bars represent the 95 percent repeated-measures confidence interval57 for the omnibus three-way interaction effect of Task Sequence, CTE, and Response Variability. CTE = competitor-task eligibility; CTe = competitor task eligible; CTi = competitor task ineligible; PRe = previous response eligible; PRi = previous response ineligible; RTs = response times; PE = percent errors; LISAS = linear integrated speed-accuracy score.

Figure 5. Target-locked reconstructed grand-average ERP waveforms, separately for all 12 experimental conditions at fronto-central electrodes as indicated in the scalp map (black dots). Upper panels: CTi, competitor task ineligible. Lower panels: CTe, competitor task eligible. Left-sided panels: PRi, previous response ineligible. Central panels: PRe, previous response eligible, response alternation. Right-sided panels: PRe, previous response eligible, response repetition. Task switch (blue lines) and task repeat (red lines) trials as indicated.

Figure 6. Left-sided panel: Raster diagram showing time course and topographic distribution of significant effects in target-locked reconstructed grand-average ERP waveforms that were elicited by task switches in comparison to task repeats (color-coded t values). Only trials on which competitor tasks remained eligible (CTe), but previous responses were ineligible (PRi), are considered here. Right-sided panels: Upper panel: Target-locked reconstructed grand-average ERP waveforms, separately for task switch and task repeat trials at the fronto-central electrodes as indicated in the scalp map below (black dots). Lower panel: The scalp topography of the switch-related P3-like amplitude differences (in μV).

Figure 7. Left-sided panel: Raster diagram showing time course and topographic distribution of significant effects in target-locked reconstructed grand-average ERP waveforms that were elicited by task switches in comparison to task repeats (color-coded t values). Only trials on which competitor tasks remained eligible (CTe), previous responses were eligible (PRe), and responses had to be repeated are considered here. Right-sided panels: Upper panel: Target-locked reconstructed grand-average ERP waveforms, separately for task switch and task repeat trials at the fronto-central electrodes as indicated in the scalp map below (black dots). Lower panel: The scalp topography of the switch-related N2-like amplitude differences (in μV).

Figure 8. Cue-locked reconstructed grand-average ERP waveforms, separately for the four cue-locked suitable experimental conditions at electrodes as indicated in the scalp maps (black dots). Left-sided panels: PRi, previous response ineligible. Right-sided panels: PRe, previous response eligible. Task switch (blue lines) and task repeat (red lines) trials as indicated.

Figure 9. Left-sided panel: Raster diagram showing time course and topographic distribution of significant main effect for Task Sequence in cue-locked reconstructed grand-average ERP waveforms (color-coded F values, alpha-corrected = 0.025) for one of the two conducted ANOVAs (see Supplementary Fig. S5, for the results of the other ANOVA). Right-sided panels: Upper panel: Cue-locked reconstructed grand-average ERP waveforms, separately for task switch and task repeat trials at frontal and posterior electrodes as indicated in the scalp map below (black dots). Lower panel: The scalp topography of the switch-related amplitude differences (in μV).