Cognitive Control: Modulating Conflict Between Competing Responses

Abstract

This thesis investigated modulation of cognitive conflict using variants of the face/name Stroop task and electroencephalogram (EEG) measures. Behavioural analyses throughout four experiments focused on reaction times (RT) and accuracy (%). EEG analyses focused on evoked upper alpha event related desynchronisation (ERD) and event related synchronisation (ERS) to assess facilitation and inhibition effects respectively. The principal focus of investigation was whether cognitive conflict is resolved through facilitation, inhibition or both. ... EEG evidence suggested that the temporal resolution of cognitive conflict involves both facilitatory and inhibitory processes in a context dependent manner. Control processes in the simple Stroop compared to the Gratton effects appear to operate independently. Study design parameters (event related versus blocked paradigm) and the temporal resolution of neurophysiological measures (EEG versus fMRI) are critical in detecting specific 'within task set' or 'between task sets' cognitive control effects. Cognitive control cannot be viewed as a singular central resource which is applied in the same way across diverse contexts with differing, specific processing demands.