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. perfo...