The Effects of Time of Day and Social Isolation on the Relationship Between Temperament and Performance

In an experiment on cancelling letters in English prose the relationship between output and degree of introversion was found to depend both on the time of day at which the task was performed and on the social situation in which subjects were tested. Performance correlated positively with introversion in morning test sessions when subjects were isolated from each other, but when testing was in the afternoon, or when subjects worked together in a group, this relationship was destroyed. The results are discussed in relation to an arousal theory of introversion‐extraversion.