Associations between developmental trajectories of movement variety and visual attention in fullterm and preterm infants during the first six months postterm

Abstract

Background: During early infancy major developmental changes, both in the variety of body movements and in visual attention, help the infant to explore its surroundings. Both behaviours depend on a gradual shift from subcortical to cortical functioning. Aims: First, to determine whether preterms reach mature levels of movement variety (the number of different movement patterns) and visual attention earlier than fullterms. Second, to determine whether individual developmental trajectories of movement variety and visual attention were associated. Finally, we compared the associations of developmental trajectories between fullterm and preterm infants. Study design: In this longitudinal study, 20 fullterm and 9 low-risk preterm infants performed a visual disengagement task every four weeks from six weeks until six months postterm. For each infant we drew up developmental trajectories for movement variety, and for frequencies and latencies of looks. We analyzed the developmental trajectories by means of general linear model (GLM) repeated measures and Monte Carlo analyses. Results: In comparison to fullterms, preterm infants showed a similar increase in movement variety over time (F(4,108) = 0.27; partial eta(2) = 0.01; P = .90). Visual attention reached mature levels four weeks earlier than movement variety. This effect was stronger in fullterm infants. Neither in fullterm nor in preterm infants did we find an association between the developmental trajectories of movement variety and visual attention. P values ranged from .37 to .99. Conclusions: During the first 6 months postterm, movement variety and visual attention developed independently. Temporarily, preterm exposure to the extrauterine environment led to shorter latencies of looks but it did not affect developmental trajectories of frequencies of looks and movement variety.