 Also, people were found to show greater orienting responses following negative than positive outcomes, including larger increases in pupil diameter, heart rate, and peripheral arterial tone 

Importantly, this preferential attendance to negative information is evident even when the affective nature of the stimuli is irrelevant to the task itself.The automatic vigilance hypothesis has been investigated using a modified Stroop task.Participants were presented with a series of positive and negative personality traits in several different colors; as each trait appeared on the screen, participants were to name the color as quickly as possible.