Abstract
In our daily life we constantly integrate vision with other sensory signals to build knowledge of the world, and to guide actions. However, would we be able to integrate multisensory signals and to plan visually guided actions if we were deprived from vision during early development? I will here report on a set of studies conducted with Ethiopian children who were classified congenitally blind as they suffered from dense bilateral cataract during early postnatal development, and were surgically treaded years later (5–19 y). We assessed the ability of these individuals to integrate visual information with other senses, and to use visual feedback to guide actions. In one task, we asked participants to haptically explore objects while simultaneously looking at them through a magnifying lens, thereby inducing a discrepancy between senses. With such perturbation tasks, we tested whether newly sighted individuals are able to integrate multisensory signals and make use of this newly acquired visual sense. In another task, we asked participants to wear prism goggles that shifted the apparent location of the pointing target. With this task we tested whether newly sighted individuals are able to minimize the systematic errors by recalibrating the sensorimotor systems. This study provides important insights into their sensorimotor learning skills, which are essential for using vision to guide actions. Current results suggest that sight-recovered children weigh vision systematically less compared with typically developing-children, and are less able to recalibrate the sensorimotor system. This suggests that the newly sighted make use of the visual sense in the concert with the other senses, but also that they require month to years to fully exploit its potentials. In this regard, the use of vision for action seems to be affected particularly strongly by the deprivation in early childhood.
Acknowledgement: DFG DIP ER 542/3-1