INHIBITION OF RETURNS IN NEWBORNS IS TEMPORO-NASAL ASYMMETRICAL

Inhibition of return (IOR) is a reduced tendency to orient toward a previously attended spatial location. Inhibition of return is caused by suddenly introduced visual cues and reflects an attentional bias toward novel locations. It is indexed by an increased latency and/or a reduced tendency of an eye movement to the inhibited location. Under monocular viewing conditions, we submitted 24 newborns (M age = 50 hours) to trials consisting of a pretest phase (a single visual cue shown at 15-degrees from fixation) and a test phase (two simultaneous, identical stimuli shown in the two visual hemifields at 15-degrees). The results showed that, the test phase, eye movements occurred more often and with a shorter latency toward the side that had not been cued in the pretest phase. It was also found that the bias against the cued hemifield (i.e., IOR) was greater in the temporal than in the nasal hemifield. It was concluded that IOR is present just after birth and is mediated by extrageniculate rather than geniculostriate pathways.