Research 
                   
             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 towards this goal in multiple ways.  In our early work, we made many discoveries about how infants determine the locations of object boundaries as they look around them and see crowded scenes of objects.  Specifically, we discovered that as young as 4 months of age, infants see similarities and differences in object shape as important information for the likely connections between object parts that are touching each other.  So, if two touching objects have similar shapes, they’re probably connected and if they have different shapes, they’re probably separate (Needham, 1998, 1999, 2000).

                Further investigations revealed that infants who explore objects more actively are more likely to succeed in using differences in object shape to see two touching objects as separate from each other (Needham, 2000).  These findings made us even more curious about the relations between infants’ perception of and their actions on objects (more on this below).  Other studies showed that later in the first year of life, infants begin using information other than object shape to determine object boundaries (color and pattern and spatial layout:  Needham & Kaufman, 1997; Physical relations like support and solidity:  Needham & Baillargeon, 1997).  In current work, we are following up on these studies by asking how infants group individual “local” elements into larger “global” wholes.  We hope to determine whether there are general principles that govern infants’ perceptual organizational skills whether the stimuli are two-dimensional, three-dimensional, rich and very object-like, or sparse and more like texture elements.  This work will help bring these ideas to a more general level.

                Having seen an object before can help us see it as one cohesive object separate from surrounding objects.  Our research has helped to make this point by showing that when we show infants a box that will appear later as part of a test display, they see it as separate from the other object(s) in the test display (Needham & Baillargeon, 1998).  Further, when we changed the features of the box (e.g., the colors on the box) between their initial and subsequent views of it, infants did not show any benefit from that prior experience (Needham, 2001).  However, when the features (e.g., colors, patterns) remained the same but the orientation of the box was changed (e.g. laying on its side vs. upright), the facilitation was maintained. So, infants need a very high degree of similarity in the features of objects when applying a prior experience to a subsequent segregation problem, but it does not seem as if there is a precise template matching that is required.  That is, infants are able to tolerate some differences between the initial and subsequent views of the object, but changes in features are unlikely to be tolerated.  Similar to adults, infants look to object features to help them determine whether they have seen an object before.  They seem to know that changes in object features are more likely to signal a change in the identity of an object than changes in its orientation.

                We also know that if infants see three of these different boxes (no one of which would have helped infants if seen on its own) all at once, infants are better able to parse the test display afterwards (Needham, Dueker, & Lockhead, 2005).  Also, when a display contains an object from a familiar category, such as a key ring, infants apply their experience with these objects from outside the lab (with other key ring toys or with actual key rings they see their parents use) to the parsing of that display, grouping the keys and ring into the same object.  We are following up on this work by providing 7-month-old infants with experiences with key rings to see what kinds of experiences are useful for infants’ formation of a key ring category or concept and which are not.

                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 object’s 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 infant’s 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 (see http://pmvish.people.wm.edu/) for more information. 

                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 2 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 1-session lab-based procedure that we can control more precisely (Needham, Tsolo, Heaton, & Libertus, 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.  The objects were moved up high, tapped on the table, swept across the table, and brought into contact with each of the infant’s hands.

                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.

                The studies we have conducted using sticky mittens make us think 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.