One of the most powerful restrictions that has been proposed on what can and cannot be represented as an object is the principle of cohesion: an object must maintain a single bounded contour over time. These studies demonstrate the precision and strength of the cohesion constraint by showing that even the simplest possible cohesion violation—an object splitting into two—is sufficient to destroy infants’ ability to successfully represent objects over time.
The dynamic and haphazard nature of real-world visual experience requires that object representations be maintained through extrinsic interruptions, such as when attention is allocated to other objects and events. What resources underlie and limit this ability? These studies demonstrated that even infants’ persisting object representations can be maintained over brief interruptions from additional independent events, just as one’s memory of a traffic scene may be maintained through a brief glance in the rearview mirror. However, this ability is nevertheless subject to an object-based limit: if the same interrupting object is simply segmented into 4 (or even 2) objects, then it will impair the maintenance of other persisting objects.
These studies explored the factors that support and limit infants’ ability to represent objects that have temporarily disappeared from view. In particular, they have examined a relatively new type of question in the infant literature—whether infants use the local visual cues of an object’s disappearance to track it as an enduring individual over time and occlusion.
In this series of studies, we demonstrated a factor enabling infants’ quantification of multiple objects. Infants only successfully computed the addition or subtraction of a small number of objects when those objects possessed contrasting properties between them. Infants This research also supports the view that the mechanisms responsible for tracking the identity of individual objects and quantifying small numbers of visual items may in fact be one and the same.
Feature binding & object individuation
(in Rhesus Macaques) (with George Newman, Laurie Santos & Brian Scholl)
The predominant theory of both infants’ and adults’ object cognition is that objects are tracked primarily on the basis of the unique spatiotemporal positions they occupy in space and time. These studies, however, have demonstrated that even unambiguous spatiotemporal evidence is sometimes insufficient for young infants to successfully establish representations of distinct individuals. For instance, infants in these experiments rely on an object’s surface properties to recall how many objects have persisted in a scene.
I have recently explored the evolutionary origins of these abilities using non-human primate subjects. By adapting traditional infant testing measures, I have shown that free-ranging Rhesus Macaque monkeys will spontaneously and reliably use color and shape bindings to individuate and enumerate objects in their environment. This result helps demonstrate that the ability to represent objects on the basis of their identifying features extends far back into our ancestral environment.
These studies explore infants’ ability to track intentional agents and their unique behavioral dispositions over time. Although infants could successfully individuate a pair of agents based on their surface features alone (for example, that they remember that the green character is “nice” and the red character is “mean”) they still understand that an agent’s identity is distinct from its surface appearance. Even when an agent’s surface properties were changed, infants expected that an agent’s disposition would persist so long as the agent moved in a spatiotemporally continuous trajectory (e.g., when the green character was subsequently painted red, they still expected it to remain “nice”).
Even young children understand that an object’s identity is not necessarily determined by its outside appearance. Instead, like adults, children sometimes base their category judgments on unseen properties of an object (e.g., their essence). What are the minimal cues necessary to compel young children to consider an object’s ‘inside’ properties when determining what category it belongs to? This series of studies demonstrated that an object’s animate motion alone is sufficient to lead children to attribute internal structure to an entity.
Spatiotemporal continuity (with Lisa Feigenson, Susan Carey & Brian Scholl)
Representation through interruptions (with Karen Wynn & Brian Scholl)
Cohesion (with Steve Mitroff, Karen Wynn & Brian Scholl)
Object individuation (with Liz Baraff & Susan Carey)
Enumeration and identity (with Karen Wynn)
Tracking agents (with George Newman, & Karen Wynn)
Agents and essence (with George Newman, Frank Keil & Paul Bloom)