Object play yields enormous benefits for infant development. However, little is known about natural play at home where most object interactions occur. We conducted frame-by-frame video analyses of spontaneous activity in two 2-h home visits with 13-month-old crawling infants and 13-, 18-, and 23-month-old walking infants (N = 40; 21 boys; 75%…

Infants imitate others' individual actions, but do they also replicate others' joint activities? To examine whether observing joint action influences infants' initiation of joint action, forty-eight 18-month-old infants observed object demonstrations by 2 models acting together (joint action), 2 models acting individually (individual action), or 1…

The relationship between infants' performance on a Piagetian scale between the ages of 12 and 24 months and the infants' scores on the Stanford-Binet at the age of 31 months was assessed. (JMB)

Investigated the possibility that evidence of frequency discrimination might be found when the experimental procedures involved the conjugate reinforcement of nonnutritive sucking. (SDH)

Nine- to 16-month-old infants explored pairs of novel toys in 2 conditions: violated expectation, in which the first toy produced an interesting nonobvious property and the second toy did not; and interest control, in which neither toy produced the interesting property. Infants persistently attempted to reproduce the interesting property in the…

Tested two competing hypotheses explaining infants' failure to search for an object in a new hiding place: (1) that the concept of object is not yet differentiated from the concept of place, and (2) that difficulties in spatial localization are responsible for the search failure. (Author/JMB)

Examined whether early differences in stress reactivity were related to self-recognition at 18 months. Found that self-recognition was related to greater cortisol response and less rapid quieting at 6 to 18 months, whereas cortisol and quieting responses of 2- to 4-month-olds did not differentiate self-recognizers and non-self-recognizers,…

Low-birth-weight infants, who received extra stimulation showed improved development through six months of age. (ST)

Investigated whether, in a sample of 30 infants, anger could reliably be observed in facial expressions as early as seven months of age. Also considered was the influence of several variables on anger responses: infants' familiarity with the frustrator, repetition of trials, and sex of the child. (Author/RH)

Examines the effect of nutritional supplementation provided to mothers during pregnancy and lactation on the mental and motor development of their infants. While neither sex nor mental differences could be attributed to supplementation, motor development in infants was affected. (Author/MP)

Used Wynn's (1992) procedure in 3 experiments to test 5-month-olds' looking-time reactions to correct and incorrect results of simple addition and subtraction transformations. Found non-systematic evidence of either imprecise or precise adding and subtracting in young infants. Results suggest that infants' reactions to displays of adding and…

Changes in children's categorization behavior between 15 and 21 months of age and the relation of these changes to developments in language, object permanence, and means-end understanding are reported. (PCB)