Gray's three-arousal model: an empirical investigation

We evaluated the validity of Gray's and Fowles' three-arousal model in two studies of criminal offenders using a continuous motor task involving rewards and punishments. Consistent with predictions for the behavioral approach/activation system (BAS), offenders displayed significant (p<0.00001) increases in response time and heart rate (HR) from a no-incentive practice phase to a reward-only (experiment 1) and active-avoidance (experiment 2) phase. Trait impulsivity was correlated with the response time index of BAS activation in experiment 1 but not experiment 2. Consistent with predictions for the behavioral inhibition system (BIS), offenders showed a significant increase in number of skin conductance responses (SCRs) (p<0.05) from a reward-only to a mixed-incentive phase in experiment 1 and a significant increase in SC amplitude to punishment cues in both experiments. Consistent with predictions for the dynamics of the model, participants showed significant slowing of response time (p<0.0001) from reward-only (experiment 1) or active avoidance (experiment 2) to mixed-incentive phases despite showing an initial tendency toward response facilitation to the onset of the punishment cue signifying the beginning of the mixed-incentive phases. Participants also showed significant (p<0.002) decreases in HR between these phases in both studies, but this effect was only evident on trial 1. The BIS-influenced response time and HR indices were significantly (p<0.05) correlated with anxiety in experiment 1, but unexpectedly, anxiety was not correlated with SC indices of the BIS in either study. Although much of the data support the validity of the Gray/Fowles model, particular findings suggest that further refinement of this theory is indicated.