Abstract
Previously we showed a developmental relationship between depth from motion parallax (MP) and smooth pursuit (SP) eye movements in infancy (Nawrot, Nawrot & Yonas, 2010; Nawrot, Mayo, & Nawrot, 2009). In infants, as in adults, depth from MP requires SP with mature gain (eye velocity/target velocity). Infants with relatively low SP gain failed to discriminate depth-sign in an MP task but those with higher gains succeeded. In the current study we further investigate the developmental link between motion, eye movements, and depth through ocular following response eye movements (OFR). OFR are visually driven, short-latency, slow eye movements assisting to stabilize gaze during observer translation (Miles, 1998; Kawano, 1999). Importantly, the OFR is depth-selective, stabilizing one depth-plane on the retina (Busettini et al, 1996). Therefore we might expect to find a relationship in the development of OFR, SP, and depth from MP. We presented 12–20 week-old infants with three tasks: A depth from MP task; a SP task; and a translating pattern OFR task. The MP and SP stimulus and procedure are identical to previous research. The OFR task included eight 0.5 sec trials in which a grating pattern translated leftwards or rightwards at 25 d/s. Saccadic enhancement of the OFR was attempted by triggering pattern translation following the infant's saccade to the center of the display. Eye movements were recorded using a Tobii X120 eye tracker. Results suggest a relationship between OFR and depth from MP across this age range. Infants who discriminated depth from MP also showed an ocular following response in both leftwards and rightward directions, while infants who failed the MP task generally failed to show the OFR. We plan to compare results from all three tasks to see whether age or eye movement maturity type is a better predictor of depth perception from MP.
This research is supported by NICHHD R15HD058179 (E.N.) and COBRE NIH P20 RR020151 (M.N).