Infant temperament and subject loss in a habituation procedure.

It has been assumed that subject loss in habituation procedures is most likely due to random factors such as the behavioral state of the infant during testing. This study explored the possibility that infant temperament might contribute to subject loss. 114 infants at 3 age levels (11, 18, and 28 weeks) were rated by their mothers on a temperament questionnaire and then subjected to a habituation procedure. Analyses showed that female infants who were unable to complete the habituation task were reported as being more fussy and unadaptable. Female infants were less likely to complete at least part of the procedure than were male infants. The results suggest that subject loss in habituation studies may be the result of nonrandom individual difference factors and not just the result of temporary fluctuations in state.