In our research, we seek to understand connections among infants perception of objects, their understanding of objects, and their actions on objects. We are working toward this goal in multiple ways.
There are many ways in which our perception of objects and our actions on objects are related. The most straightforward example of this is that we must accurately perceive an objects boundaries and location before we can plan an accurate reach for it. Our experiments show that infants plan different kinds of reaches for an object depending upon where they perceive its boundaries to be (Needham, 1999). Infants were shown a display that consisted of two separate blocks or of one long block (that was two blocks glued together). Once the experimenter demonstrated the composition of the display (as one or two pieces), she placed it on the table within the infants reach and encouraged the infant to reach for it. The results showed that, by 12 months of age, infants show a clear difference in the way they reach for two blocks versus one block. For two blocks, they tend to use two hands and to avoid the center separation point between the blocks when placing their grasps on the objects. For one block, they tend to use a single hand and to place their grasp anywhere along the object (there was no tendency to place the grasp at the center of the block or on either end). Further work by Peter Vishton and his colleagues has shown this same kind of pattern in younger infants.
We have also revealed more perceptual-motor connections early in infancy that relate to the transition into reaching. In this work, we have provided infants with the ability to pick up toys using sticky mittens; mittens with the palms covered in soft Velcro that can pick toys up that have hard Velcro on them. Just by placing their hand near the toy, they can gain control over the toy and move it through their visual field (which is exactly what they do). Our studies have shown that pre-reaching infants who have been trained with sticky mittens 10 minutes a day over two weeks or so show a number of behaviors that are not shown by infants the same age who have not had this training. Specifically, trained infants show more looking at objects, more mouthing of objects, and more switching back and forth between looking and mouthing. They also show more swatting at toys that seems intentional (meaning that they were looking at the toy before making contact with it) whether they are wearing the mittens or not (Needham, Barrett, & Peterman, 2002). In subsequent work, we have determined that by the end of training, infants engage in significantly more independent reaching than age-matched infants who are not receiving training (Libertus & Needham, in prep).
We have also determined that similar effects can be observed during a one-session lab-based procedure that we can control more precisely (Needham, Tsolo, Libertus, Gibson, & Heaton, in prep). In this research infants are given pre- and post- experience exploration tasks, and in the intervening interval we provide infants with one of two kinds of experiences. In the active experience condition, infants wear the sticky mittens and are offered the opportunity to move objects as described above. In the passive experience condition, infants wear mittens that are not sticky and watch while the experimenter produces object motions that were designed to mimic the kinds of movements infants in the active experience tend to produce.
Although there were no significant differences at the pre-experience phase, in the post-experience phase there were significant differences in the predicted direction for measures such as latency to touch the object (shorter latencies in active group), distraction (less distraction in active group), and touching while looking (more in the active group). This set of findings makes clear that it is not just the overall amount of exposure to the toys or attention from the parent or experimenter that is producing these effects, because both groups received equal amounts of exposure in the study. The findings support the claim that infants learn about the consequences of their actions when they get exposed to them (regardless of whether they can produce them fully well on their own yet or not). We hypothesize that active experience with these consequences may well be critical to infants learning about their motor capabilities as these change throughout the first two years of life.
This research has led us to believe that there is an important role for motivation in the development of new motor abilities during infancy. All actions must have an instigating force of some kind, and we are studying the ways in which the construct of motivation can help us understand the conditions under which infants do and do not reach for objects as well as other aspects of their motor behavior.
Our current work is investigating these perception-action-cognition issues further in typically developing infants as well as in infants who are following atypical paths of development. We are studying visually impaired infants to see whether their transition into reaching can help us devise therapeutic treatments for them as well as create a better understanding of the development of reaching in blind infants and sighted infants. We are also studying preterm infants to determine whether we can help them develop midline behaviors earlier than they usually would with the help of our sticky mittens. And we are studying children at risk for developing Autism to find out whether their early perceptual, cognitive, and motor skills can help us identify and begin to help these infants as early as possible.