Aishwarya Ravi¹, Stephanie A Biehn¹, Fuseina Safianu¹, T Rowan Candy¹; ¹Indiana University

Purpose Infants experience motion in retinal images resulting from self-motion, eye movements, and motion of objects in their visual periphery. Adult studies have shown scaling of sensitivity to motion from the fovea to the periphery. Our goal was to determine this scaling in infants for dynamic 1/f textures. Methods A spatially 1/f noise texture was presented on a rear-projection screen (PROPixx projector, VPixx) at a series of diameters (3, 5, 8, 12 deg) and speeds (2, 8, 16 deg/s) on a mean luminance background. Eye movements were recorded using an Eyelink 1000 Plus (SR Research, 1000 Hz). A 9-point calibration routine was performed before presenting the stimulus at the center of the screen. It moved in a series of six interleaved linear smooth ramps and steps to two of three eccentricities (5, 12, 20 deg) within a single run. A total of 6 steps (2 diameters x 3 speeds) each to 5 and 12 deg eccentricity, and 12 steps (4 diameters x 3 speeds) to 20 deg eccentricity were presented across four runs (24 steps). The experimenter controlled the stimulus presentation. Results Adults and infants (12-20 weeks) provided stimulus-driven visual tracking to linear ramps and saccadic responses to steps at all three eccentricities (5, 12, 20 deg). After applying threshold criteria to define a response to a peripheral target, proportions were highest at 3 deg diameter & 8 deg/s speed at 5 deg eccentricity, 5 deg & 32 deg/s at 12 deg eccentricity, and 12 deg & 32 deg/s at 20 deg eccentricity for infants. In contrast, adult proportions were >80% across all stimulus combinations. Conclusion This preliminary study describes the scaling in the developing visual system’s sensitivity to motion, and the requirements for an equally sensitive clinical test with eccentricity for naturalistic spatial image statistics.

Acknowledgements: NEI R01 EY014460