Attentional asymmetry in orienting and alertness and its relationship to temperament: A longitudinal study of infants aged 6-24 months.

Previous research suggests that difficulties in orienting to visual stimuli directed by the right hemisphere are related to parental reports of distress and may be an early sign of autism spectrum disorder (ASD). One possible reason for this difficulty is infants' ability to achieve high levels of alertness, which also depends on the right hemisphere. This study examines the relationship between phasic alertness and asymmetry in visual orienting in typically-developing 6-24-month-old infants using the overlap paradigm. Participants were given a spatially non-directive warning signal shortly before the onset of the peripheral target. The signal reduced latencies in both overlap and no-overlap conditions. No main effects of age and visual field or interaction were found. However, results confirm the negative association between temperamental soothability and disengagement difficulty toward the left visual field at 6 months. This is discussed from the viewpoint of early left visual field attentional bias in relation to social cognition.