A total of 114 infants at three age levels (11, 18, and 28 weeks) were rated by their mothers on a termperament questionnaire and subjected to a habituation procedure. 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.…

In order to investigate sex-role identity and learned helplessness as possible mediating factors affecting performance on formal operational tasks, the responses of 60 male and female adolescents were assessed. Contrary to expectations, the performances of individuals with feminine versus masculine sex roles did not differ significantly.…

Examined relation between individual differences in inhibitory control (IC) and theory-of-mind (ToM) performance in preschoolers. Found that IC was strongly related to ToM, even after controlling for several important factors. Inhibitory tasks requiring a novel response in face of a conflicting prepotent response and those requiring delay of a…

Imitation, vocabulary, pretend play, and socially insightful behavior were investigated in 5,206 same- and opposite-sex 2-year-old twin pairs in the United Kingdom. Individual differences in imitative ability were due to modest heritability (30%), while environmental factors shared between twins (42%) and unique to each twin (28%) also made…

Bruner's (1973) review of infant skill development is updated and extended by (a) placing it in the context of recent motor learning research; (b) discussing the concept of efference in its most recent conceptualization; and (c) explicating certain implicit themes relevant to a theory of infant motor intelligence. (ED)

Habituation to single female faces and to single geometric patterns was observed separately in two groups of infants who participated in two sessions separated by 10 days. Habituation was found to be distributed into three patterns and showed moderate but significant reliability between assessment sessions. (Author/RH)

Delay/response inhibition in the presence of an attractive stimulus and compliance with maternal directives in a clean-up task were observed among subjects 18, 24, and 30 months of age. Results suggested (1) achievement of self-control is a major developmental accomplishment, and (2) individual differences in self-control emerge and are…

Challenges the notion that long-term memory retrieval efficiency is a potential source of individual and developmental differences in cognitive functioning. Fourth-grade, eighth-grade, and college-aged subjects participated in a task using the Posner letter matching paradigm and were assessed with tests of verbal and spatial ability. (Author/CB)

This reply refers to PS 502 443. (CB)

Provides an introduction to a special section on developmental behavioral genetics (the study of genetic and environmental influences on individual differences in behavioral development), discussing the potentialities of the interdiscipline and presenting an overview of the following articles. (Author/RH)

Discusses implications of a study of middle-class infants seen in the Ainsworth strange situation at 12.5 and 19.5 months; the investigation produced results inconsistent with the corpus of previous findings. (Author/RH)

The gross-motor activity of 27 three- and four- year-olds was assessed through teacher ratings, parent responses to the activity scale of the Colorado Childhood Temperament Inventory, and data from uncalibrated actometers worn by children during free play. Activity scores composited across multiple actometers had high reliability and correlated…

Both between- and within-group differences in children ages nine to eleven identified as having reflective or impulsive cognitive tempos. Cognitive tempo was first assessed using Kagan's Matching Familiar Figures test, and children were later tested on the Raven's Standard Progressive Matrices. (Author/RH)