תאריך:
ה', 10/05/201812:30-14:00
מיקום:
Wechsler
Visual function following prolonged periods of early-onset deprivation:
Understanding others' actions is an essential aspect of behavior (e.g. for social interaction). In fact, we can predict the outcome of an action well before its completion. Furthermore, some of our actions are triggered by automatic processes elicited by observing others' actions: Infants recognize the target of gaze of others, and direct their gaze to the same object within months from birth. Similarly, we better imitate actions when they are spatially congruent with others' actions. Still, it is unclear if these behaviors, are innate or require visual experience to develop.
We tackled these issues by studying a unique group of newly-sighted children that suffered for years from dense bilateral cataract since early infancy. After cataract removal surgery, their visual acuity typically improved allowing most of them to recognize hand actions or gaze direction. In the first experiment, the subjects watched videos of hand-action either grasping an object or pointing to it. The object was located at the left or right side of the screen. They reported the action type (pointing / grasping) and direction (left/right) on each trial. The newly-sighted required longer action-video presentations to discriminate between the two actions, whereas age-matched controls performed equally well in both tasks. We also tested if viewing a specific hand action (tapping with one hand), would speed up the response-compatible action (e.g. automatic imitation), and whether seeing a person gazing in one direction would facilitate reaction to the gaze-compatible target. The newly-sighted were less affected by such viewed-actions (hand action or gaze direction) than controls, even two years after the operation.
Collectively, our result suggest that visual experience is necessary for the development of automatic "action understanding" behavior. At the very least, our results indicate that if these behaviors were based on innate mechanisms, they are susceptible to long periods of visual deprivation.