Abstract: Previous studies have shown that older adults tend to evaluate faces as more trustworthy than do younger adults, which is referred to positivity effect in facial trustworthiness judgment. The positivity effect is due to age-related declines in cognitive capacity. We investigated the age difference in positivity effect for older adults judging young and old faces and whether cognitive declines caused greater positivity effect. Younger, young older, medium older, and old older adults in Experiment 1 rated trustworthiness of young and old faces with neutral expression on a 7-point Likert scale. Results showed a positivity effect for all three groups of older adults only when judging old faces but not young faces. No age difference in positivity effect was observed. Experiment 2 compared the positivity effect in older adults with high and low cognitive level. There was a positivity effect in older adults with high cognitive level in rating old faces, but no positivity effect in older adults with low cognitive level. The results indicate that the positivity effect in older adults relies on normal cognitive level. However, cognitive decline is not responsible for the occurence of positivity effect.

Key words: positivity effect, facial trustworthiness judgment, older adults, first impression formation