Extraversion and behavioural approach system in the stimulus analysis and motor response initiation

In this study, we attempt to validate previous findings on extraversion-related differences in speed of sensorimotor processing and to extend them into Behavioural Approach System (BAS) subtraits within the framework of the revised Reinforcement Sensitivity Theory (rRST) of personality. Here, we assessed psychological traits of extraversion (E), four BAS facets (Goal-Drive Persistence, BAS-GDP; Reward Interest, BAS-RI; Reward Reactivity, BAS-RR; Impulsivity, BAS-I), Behavioural Inhibition System (BIS), and Fight-Flight-Freeze System (FFFS) in 51 volunteers (28 women). Stimulus-locked lateralized readiness potential (S-LRP), response-locked LRP (R-LRP), stimulus-locked and response-locked forearm electromyogram (S-EMG and R-EMG), and P3 components of the event-related potentials (ERPs), were recorded during the performance of a two-choice Go/NoGo visual letterdigit discrimination task varying in task difficulty. High extraverts, relative to introverts and individuals high relative to low on BAS-RI, were more likely to exhibit shorter S-LRP latencies and stimulus- and response-locked EMG latencies. Additionally, high BAS-I had a shorter R-RLP latency than low BAS-I participants for the difficult task. High FFFS levels were associated with longer S-LRP and S-EMG latencies, while high BIS levels had larger response accuracy. Extraverts, relative to introverts, along with those high relative to low on BAS-RR and BAS-I, exhibited smaller P3 amplitudes. The faster cortical premotor initiation, found in individuals high on extraversion, BAS-RI and low on FFFS, may account for their faster peripheral motor response initiation and execution. Smaller P3 amplitudes in extraverts and individuals high on BAS-RR and BAS-I may indicate reduced perceptual processing capacity in these individuals.