Gérard Malcuit

The Development of Infants' Responses to People and a Doll: Implications for Research in Communication

Abstract The behavior of eight babies was studied longitudinally when facing people and a doll. The eight babies were observed biweekly from 3 to 25 weeks. Among them, five continued to be observed on a monthly basis up to 45 weeks. At each visit the babies were presented with their mother, a female-stranger, and a doll who were alternately active and inactive. Each condition lasted 45 s at 3, 5 and 7 weeks and 60 s thereafter. The results showed that by 5 to 9 weeks the proportion of time babies looked, smiled and vocalized as well as moved their arms toward people differed significantly from those produced to the doll when confounding variables such as familiarity and activity of the stimuli were manipulated. This pattern of early differential responsiveness, together with important developmental changes over the 10-month period, suggests that infants are reacting to communication-related cues in the presence of social stimuli. The implications of these findings for the development of communication are discussed.

Cardiac and Behavioral Responses to Rocking Stimulations in One- and Three-Month-Old Infants

Cardiac and behavioral reactions to lateral rocking stimulations were analysed at two different ages (1 and 3 months) and at two speeds of motion for the younger infants. Sixteen 1- and 3-mo.-old infants received 12 10-sec. trials of four complete cycles of vestibulokinesthetic stimulation (rapid rocking) and another group of 10 1-mo.-olds received one complete cycle in the same time period (slow rocking) provided by a motorized cradle. Stimulations were given when infants were in an alert state. Rapid and slow rocking induced similar cardiac responses in younger infants; these responses varied according to the type of motor reaction observed at stimulus onset. Cardiac acceleration was shown with motor activation and cardiac deceleration with motor quieting. In 3-mo.-olds, cardiac deceleration appeared with both types of motor reaction. A strong link between cardiac and behavioral responses in younger infants may prevent the occurrence of the usual simple cardiac index of orienting (heart-rate deceleration). In older infants, cardiac deceleration to rocking stimulation appeared even when it produced concomitant behavioral arousal. Vestibulokinesthetic stimulation is interpreted as having an important homeostatic effect on the young organism.