Abstract: The influence of Happiness and Distress on mental task performancewas studied in infancy aged 16 months old(Denver subjects) and 16--18months old (Biejing. subjects). The study was a merged data analysis ofboth Denver and Beijings' samples. The two samples showed no signifi-cant difference. The results indicate: 1.The influence of Happiness and Distress on mental performanceis different, The performing effects in the Happiness group are betterthan in the Distress group. They appeared in the following. performingstrategies: "Direct Grasp", "Watching" and "Reaching". 2.The correlations of intensity in Happiness and Distress onperforming effects are different. The Happiness group shows a curvilinearrelation; that is, the highest and lowest levels of Happiness show worseeffects than the middle level. The optimum point of emotional arousal iswithin the range of 22--55% of the whole eliciting period. The Distressgroup shows an ascending slope linear relation: that is, the stronger thedistress, the worse the performing effect.

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