The effect of mild acute psychological stress on attention processing: an ERP study

We aimed to investigate the effect of mild acute psychological stress on attention processing by adopting a consecutive task paradigm. In each trial, a probe stimulus (left or right arrow) was presented immediately after a mental arithmetic task (psychological stressor). Participants were asked to estimate whether the product of a multiplication term was above 10 or not, either with (stress block) or without (control block) time pressure and social-evaluative threat. When the probe was presented, participants were asked to judge the direction of the arrows. Increased subjective stress and negative affect were found for the stress versus control trials. For the probe task, reaction times were faster in the stress block than in the control block. Event-related potentials locked to the arrows revealed that (a) fronto-central N1 was enhanced in the stress block compared to the control block. This finding might indicate that stress amplified processes of early perception and that vigilance and sensory intake were augmented. (b) fronto-central N2 was enhanced in the stress block compared to the control block. This finding might reflect increased effort to control selective attention in completing the probe task. (c) less positive P3 was evoked in the stress block than in the control block. This finding potentially reflects the fact that fewer attentional resources were engaged in processing the probe, or that the activity associated with the process of response evaluation was decreased. In sum, mild acute psychological stress exerts a dissociable effect on the neural subprocesses of attention.