Learning to Reach Infancy
Understanding the process by which infants learn to reach for objects has remained one of our most central area of study. The classic view that dominated for many decades was that infants depended strictly on visual control to guide their arm to the target location. It was believed that through active visual control, infants progressively learned how to produce more direct arm trajectories to contact the target successfully. This view is no longer sustained. Research has demonstrated that reaching can emerge without needing visual guidance of the arm, and my contribution to this line of work has revealed that learning to reach is a much more complex process that is embodied and requires many behavioral components to come together in order to allow goal-directed reaching to form. Dr. Corbetta’s earlier work with Esther Thelen has shown that learning to reach involves discovering how to calibrate the speed of the movement in order to create direct arm trajectories to the target. Modulating movement speed is not a process controlled visually, but rather one that is monitored continuously through proprioception. Learning to control the arm proprioceptively involves the exploration of a wide range of movements, thereby allowing the selection and mapping of movements with their respective outcomes. More recently, the lab has used eye-tracking to examine more closely how vision eventually contributed to the formation to early reaching in 2-4 months old infants. We discovered that within the first weeks of learning to reach, infants in fact, learned to map vision on their movement, and not the reverse as had been widely believed, verifying that initially learning to reach is primarily an embodied process. All those discoveries were revealed through dense longitudinal studies.
- Thelen, E., Corbetta, D., Kamm, K., Spencer, J. P., Schneider, K., & Zernicke, R.F. (1993). The transition to reaching: Mapping intention and intrinsic dynamics. Child Development, 64, 1058-1098.
- Thelen, E., Corbetta, D., & Spencer, J. P. (1996). The development of reaching during the first year: The role of movement speed. Journal of Experimental Psychology: Human Perception and Performance, 22, 1059-1076.
- Thelen, E., & Corbetta, D. (1994). Exploration and selection in the early acquisition of skills. International Review of Neurobiology, 37, 75-102.
- Corbetta, D., Thurman, S.L., Wiener, R.F, Guan, Y, & Williams, J.L. (2014). Mapping the feel of the arm with the sight of the object: On the embodied origins of infant reaching. Frontiers in Psychology: Cognitive Science, 5:576. doi: 10.3389/fpsyg.2014.00576
Visual Attention in the Context of Infant Reaching
One recurrent question brought about by the studies summarized above concerns what infants are looking at when reaching for objects. For example, when they are showing regressions in reaching during transitions in locomotion, are they still paying attention to the physical properties of objects? And, when they are producing systemic motor responses, even though they have seen and explored haptically the object before, are they taking time to look at the objects before making their decision to reach? In recent years, we have begun using eye-tracking technology in the context of looking and reaching for objects to answer those questions. Eye-tracking has become a very popular research tool among infancy researchers, but my lab is one of the few to have applied this technology to the context of infants’ goal-directed actions. We performed our first attempts to record gaze in 6- to 10-month-old infants while reaching for objects using a head-mounted eye-tracker. These data suggested that age was not a factor in predicting patterns of visual scanning of the toy-target prior to reaching. However, scanning vs non-scanning infants produced very distinct movement kinematics when reaching for the object, suggesting that visual attention processes may have played a role in the planning and execution of the movement. In a subsequent study we recorded infant gaze in relation to a reaching task using a remote eye-tracker. These data indicate that infants’ vision is primarily directed to the larger, most visible parts of the objects and thus they tend to look more at those salient areas (i.e. cup body instead of handle). When reaching, they also seem to direct their hand to the part of the object they looked at the most suggesting the existence of a strong spatial mapping between eye and hand (at least at the older ages, not in emerging reachers). Visual attention to the largest object on the scene was also observed in another study not involving reaching.
- Corbetta, D., Guan, Y., & Williams, J. L. (2012). Une réévaluation du rôle de la vision dans le développement de la préhension chez le bébé. [A re-evaluation of the role of vision in the development of reaching in infancy]. Enfance, 64, 49-60.
- Corbetta, D., Guan, Y., & Williams, J. L. (2012). Infant eye-tracking in the context of goal-directed actions. Infancy,17, 102-125.
- Guan, Y., & Corbetta, D. (2012). What grasps and holds 8-month-old infants’ looking attention? The effects of object size and depth cues. Child Development Research, 2012, Article ID 439618, 10 pages, 2012. DOI:10.1155/2012/439618.
- Corbetta, D., Thurman, S.L., Wiener, R.F, Guan, Y, & Williams, J.L. (2014). Mapping the feel of the arm with the sight of the object: On the embodied origins of infant reaching. Frontiers in Psychology: Cognitive Science, 5:576. DOI: 10.3389/fpsyg.2014.00576