Intertrial RT variability affects level of target-related interference in cued task switching
Provost, A and Jamadar, S and Heathcote, A and Brown, SD and Karayanidis, F, Intertrial RT variability affects level of target-related interference in cued task switching, Psychophysiology pp. 1-15. ISSN 0048-5772 (2017) [Refereed Article]
In cued task switching, performance relies on proactive and reactive control proc-esses. Proactive control is evident in the reduction in switch cost under conditionsthat promote advance preparation. However, the residual switch cost that remainsunder conditions of optimal proactive control indicates that, on switch trials, the tar-get continues to elicit interference that is resolved using reactive control. Weexamined whether posttarget interference varies as a function of trial-by-trial variabil-ity in preparation. We investigated target congruence effects on behavior and target-locked ERPs extracted across the response time (RT) distribution, using orthogonalpolynomial trend analysis (OPTA). Early N2, late N2, and P3b amplitudes were dif-ferentially modulated across the RT distribution. There was a large congruence effecton late N2 and P3b, which increased with RT for P3b amplitude, but did not varywith trial type. This suggests that target properties impact switch and repeat trialsequally and do not contribute to residual switch cost. P3b amplitude was larger, andlatency later, for switch than repeat trials, and this difference became larger withincreasing RT, consistent with sustained carryover effects on highly prepared switchtrials. These results suggest that slower, less prepared responses are associated withgreater target-related interference during target identification and processing, as wellas slower, more difficult decision processes. They also suggest that neither generalnor switch-specific preparation can ameliorate the effects of target-driven interfer-ence. These findings highlight the theoretical advances achieved by integrating RTdistribution analyses with ERP and OPTA to examine trial-by-trial variability in per-formance and brain function.