Studies have reported that depressed patients have difficulties in disengaging attention from negative information, but knowledge of the temporal characteristics of this disengagement is still rudimentary. Our objective is to reveal the temporal characteristics of attentional disengagement from emotional facial cues in depression.

We recruited 22 depressed patients and 22 healthy controls to participate in a cued target-response task with emotional facial expressions (happy, natural, and sad) as cues and three types of cue-target intervals (CTIs: 350ms, 1000ms, and 1500ms). Both behavioral and electroencephalography (EEG) data were collected from each subject while performing the task. Then, both behavioral results and event-related potentials (ERPs) were analyzed across groups (depressed patients and normal controls), emotional types of facial cues (happy, natural, and sad), and CTIs.

Both depressed patients and healthy controls had shorter response times in the conditions of CTI=1000ms and 1500ms than in the condition of CTI=350ms but had no significant difference in response time between the conditions of CTI=1000ms and CTI=1500ms. The contingent negative variation (CNV), a well-documented ERP marker of cue-induced expectation of the forthcoming target, clearly appeared about 1000ms following cue onset for normal controls and 1300ms following cue onset for depressed patients. Statistical analysis by repeated-measures Anova showed that a main group effect exists for the average amplitudes of ERPs at electrode Cz 930ms after cue onset, while there was no main effect of cue or interaction effect between cue and group.

These results suggest that normal controls complete their attentional disengagement from emotional facial expression between 350ms to 1000ms after cue offset, while depressed patients complete their attentional disengagement later than that of normal controls but earlier than 1500ms from the perspective of CNV onset, though the two groups have no significant difference in response time in the conditions of CTI=1000ms and CTI=1500ms respectively.