Are real-world objects represented as bound units? Independent decay of object details from short-term to long-term memory

Brady, Konkle, Alvarez & Oliva

Are all properties of a real-world object stored together in one bound representation, or are different properties stored independently?  Object information often appears to be bound in short-term memory, but this could be because multiple properties are concurrently encoded from the same objects.  Here we use short-term and long-term memory paradigms to examine the independence of different object properties.  If object properties decay independently from short-term to long-term memory, then we can infer that object information is not stored in a single integrated representation.

In Experiment 1, we showed observers 120 real-world objects that were arbitrarily colored and categorically-distinct. Following presentation of the objects, we used a 2AFC to probe either the objects' color or object state (e.g., open vs. closed) after either a short-delay or long-delay.  We found that despite being matched in short-delay performance, arbitrary color information decayed much more rapidly than the more meaningful state changes after a long delay (7% for state versus 13% for color, p<0.05).

In Experiment 2, we showed observers a set of categorically-distinct objects that varied in two meaningful dimensions (object exemplar and state) which observers remember equally well on average. This was followed by a 4AFC consisting of two exemplars (one familiar, one novel) each in two states (one familiar, one novel) after either a short-delay or long-delay. After a short delay, observers frequently remember both properties about the same objects, but after a long delay they are more independent (18% decrease in boundedness over time, p<0.05).

These data indicate that observers do not form a single bound object representation in memory: instead, conceptually meaningful object properties persist while arbitrary properties like color are forgotten.  Even for different object properties that are forgotten at about the same rate, observers tend to forget these properties independently of each other for individual objects.

Brady,T. F., Konkle, T., Alvarez, G. A., & Oliva A. (2011). Are real-world objects represented as bound units? Independent decay of object details from short-term to long-term memory Poster to be presented at the annual meeting of the Vision Sciences Society, May 6-12, Naples, FL.