Geophysical Variables and Behavior: XXIV. Seasonal Factors in Extraversion
In a recent study by Fourie a post hoc observation was made that summer-born subjects obtained a higher mean extraversion score on the Eysenck Personality Inventory than winter-born subjects, with spring- and autumn-born subjects scoring neatly between the two extremes. The present study was designed to replicate this finding and to investigate the relationship between extraversion and mean day temperature around the time of birth. The Eysenck Personality Questionnaire was applied to 350 women, all born in the same 12-mo. period. Analysis of variance performed on the extraversion scores verified the hypothesis of a seasonal difference. Correlations between extraversion scores and various day temperatures and mean day temperatures, though of small magnitude, were without exception positive and significant, indicating a definite relationship between extraversion and day temperature around the time of birth.