Selective attention in depression

In four experiments the effect of depression on selective attention was examined. Each subject was assigned two computer-presented stimuli to a right-hand response and two stimuli to a left-hand response. Targets were flanked with either compatible stimuli (assigned to the same response) or with incompatible stimuli. The difference in response time to targets on the two types of trials was used as a measure of selective attention. Certain experimental conditions required subjects to make an additional, difficult stimulus identification prior to target response. This part of the task was designed to manipulate the size of the focus of attention. The first study demonstrated that depressed subjects had significantly more difficulty, compared to non-depressed subjects, ignoring the irrelevant flankers and concentrating on the targets. The trend of the means of the fourth study supported this conclusion. The second and third studies, intended specifically to compare clinically and sub-clinically depressed subjects, did not evidence effects of depression on attention nor were there interpretable differences between the two types of depressed subjects. There was an unexpected effect of gender in these studies. Females had less difficulty ignoring the flankers and attending to targets than males, particularly in the more strongly focused conditions.