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Odile Brosseau-Lachaine, Christian Casanova, Jocelyn Faubert; Maturation of optic flow motion sensitivity in infants. Journal of Vision 2004;4(8):603. doi: https://doi.org/10.1167/4.8.603.
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© ARVO (1962-2015); The Authors (2016-present)
Motion analysis is a fundamental aspect of vision. Development of fronto-parallel motion processing has been extensively studied, but little is known about the early sensitivity of a very ecological motion, namely “optic flow”, a large-scale pattern perceived during locomotion. The present study was aimed to examine the maturation of infants' sensitivity to optic flow stimuli during the first year of life. Using force choice preferential looking technique, coherence thresholds where measured in infants between 8–44 weeks of age. The stimulus simulates an observer travelling down a tunnel, where the randomly distributed dots are moving in a radial trajectory (expansion and contraction). Exp. 1: Infants were studied cross-sectionally by a constant stimuli method. Thresholds for expanding flow fields were measured in 52 infants (2, 4, 6, 8, 10 months). Exp. 2: A longitudinal follow-up was done with 7 subjects (at 2, 4, 6, and 8 months), using the same stimulus. Exp. 3: Coherence thresholds for the latter subjects were estimated by a staircase method (2-up/1 down), for the 2 directions of motion (expansion and contraction). The infants tested with this paradigm were also followed longitudinally. The first experiment revealed a significant improvement of optic flow sensitivity throughout the developmental period studied (Pearson correlation; p<0.05, R=0.28). In the second experiment, thresholds were found to be very variable at 2 months of age but showed a clear tendency to cluster in older infants. To date, data from the third experiment suggests that the threshold for perceiving expanding flow fields may be lower than that for contracting fields. Overall, this study indicates that infants can discriminate between complex motion stimuli such as optic flow, and non-coherent motion, as early as 8 weeks of age. The slight improvement in optic flow coherence thresholds during infancy, likely reflects the maturation of cerebral areas subtending motion integration.
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