Publication Type: Individual Poster
Abstract: Background and Aims: A number of studies have demonstrated the link between maternal sensitivity in early infancy, infant cortisol reactivity, and subsequent attachment security in later infancy. Furthermore, attachment security has been linked to cognitive processes in toddlers, as has maternal synchrony and infant intelligence. However, the search for evidence of infant cortisol reactivity in response to novel situations, maternal-infant synchrony, and their relationships to infant learning is a virtually unexplored area.
Methods: Data were collected on 121 primiparous mothers and their 6-month-old infants. Saliva was collected from mothers and their babies at the beginning of the session, and 30 minutes later, after a 10-min videotaped interaction period and two discrimination tasks. The amount of cortisol in the saliva samples was determined. Behavioral synchrony between mother and infant was assessed using established behavioral criterion by observing specific behaviors of mother (e.g., vocalize, soothe) and infant (explore, fuss/cry) in 10-sec intervals. Infant learning was assessed in two types of discrimination tasks, one involving faces and the other, rhymes. For the face experiment, color photos of womens’ faces were modified using software. One photo was the infant’s mother, another was a female who looked similar to mother, a third looked different mother, and a final photo was a female that every infant viewed. Nonmodified and modified versions of a given face (e.g., the infant’s mother) was displayed simultaneously on screens on the infant’s right and left sides. A standard visual preference paradigm presented sixteen 8-sec trials. For the rhyme experiment, audio recordings were made of each infant’s mother speaking two modern nursery rhymes. Mothers read one rhyme (the familiar rhyme) to their infants as often as they wished during a two-week interval immediately before their session. On alternating trials of the experiment, infants heard the unfamiliar or the familiar rhyme. Looking times toward each side speaker were recorded over 8 trials.
Key Results: Infants whose cortisol measurably declined during the session showed a looking time preference for mother’s face compared to the other three categories of faces, while those whose cortisol did not change or appreciably increased did not. Those infants whose cortisol levels decreased also listened to the familiar rhyme significantly longer than infants whose cortisol increased. Infants whose mothers were in the highest quartile of synchronous behavior with their infants discriminated between modified and nonmodified versions of two face categories, one of which was mother, and showed significantly greater looking time preferences for their mother’s face compared to the other three categories.
Conclusions: Infants’ decreasing cortisol levels and mothers’ greater attunement to her baby both predict 6-month-old infants’ preferences for, and discrimination of, familiar stimuli involving their mothers’ faces and voices.