Objective    To determine the effect of valence strengths of different emotional stimuli on cognitive control in individuals with depressive symptom.     Methods    Six hundred undergraduates from one university in Chongqing were tested with Beck depression inventory (BDI)

and Self-rating Depression Scale (SDS). There were totally 585 valid questionnaires obtained. Among them

A total of 23 individuals with depressive symptom (mean age 20.8

male to female 9:14) and 23 age- and gender-matched health subjects were enrolled in this study. Emotional Oddball task was carried out on them to compare their accuracies and reaction times to target stimuli under the effect of valence strengths of different emotional stimuli.     Results    The accuracies data showed that there was significant difference in different valence strength for health group (F=11.221

P0.01)

and also for depressive symptom group (F=12.310

P0.01). The accuracies of target stimulus in highly negative

neutral and moderately positive were significant higher than highly positive and moderately negative in either group(P0.05). But there was no difference between highly positive and moderate negative. The data on reaction times showed that there was significant difference in different valence strength for health group (F=2.903

P0.05). The reaction times of target stimulus in highly negative

neutral

moderately positive and highly positive were significant longer than moderately negative(P0.05). There was also significant difference in different valence strength for depressive symptom group (F=3.256

P0.05). The reaction times of target stimulus in highly negative and moderately positive were longer than neutral and high positive(P0.05).     Conclusion    Different emotional stimuli have different effects on cognitive control in the individuals with depressive symptom. The depressed would be delayed to cognitive control when valence intensity of negative stimuli is increasing

while they would advance to cognitive control when that of positive stimuli is increasing.