Abstract
Early perceptual development has long been described as a process driven by experiences. However, the underlying mechanisms regarding how experiences shape perception are still unclear. Recent advances in neuro-science suggest that the brain relies primarily on top-down neural networks to adapt perceptual systems based on prediction signals learned from the environment. Recently, this neural capacity has been found available at birth, suggesting that it might be the mechanism that translates experiences into developmental changes in perception. We examined this hypothesis by investigating whether infants’ motion perception can be modulated by learned predictive cues. Twenty 6-month-olds first learned two audio-visual associations between musical melodies and motion directions, which were depicted by coherent motion of 720 dots (Fig. 1). Infants’ perception of motion directions was demonstrated by smooth pursuing eye movement in motion directions (Fig. 2). We then examined whether they could use the predictive melodies to induce motion perception with motion omission trials, where every dot moved in a random direction without forming any coherent motion pattern. In these omission trials, even no motion pattern was presented, infants still exhibited consistent leftward and rightward eye movement in accord with the predicted motion directions by the melodies in the motion omission trials. A control experiment, which presented static dots after the predictive melodies, failed to show this prediction-based eye movement, suggesting it was motion perception, rather than directional eye movement, induced by the predicting melodies. We further found that the top-down signals were equivalent to 10–20% motion signals in inducing motion perception (Expt3). These findings suggest that the ability to translate predictive cues in the environment into adaptive perceptual changes is already sophisticated at 6 months of age. It further suggests that top-down neural networks via feedback neural connections, play a key role in driving perception development early in life.