Abstract # 128:

Scheduled for Friday, June 19, 2015 10:45 AM-11:00 AM: (Cascade F) Oral Presentation


WHAT IS THE CONTRIBUTION OF MEMORY ERROR TO CHIMPANZEE FORAGING EFFICIENCY?

C. R. Menzel and K. Sayers
Language Research Center, Georgia State Univ., Decatur, GA 30034, USA
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     Chimpanzees are capable of rank ordering the expected value of hidden food items by item type, quantity, proximity, and the amount of time since viewing. We hypothesized that a subset of all items is maintained in active memory. When higher value items are removed from the decision space, lower value items rise in activation. If an essential feature (e.g. location) of the best available remaining item is not retrieved from memory, the corresponding feature from a similarly ranked goal is substituted. Thus, memory errors are expected to preserve the value of the next recovered item. We examined errors shown by three adult chimpanzees in foraging tests that required animals to remember multiple items and features of items. The apes sometimes failed to recover highly valued items, mislabeled the type of item hidden in a location by lexigram, or designated an incorrect location in response to an experimenter-initiated query. Substitution errors for “what” and “where” components of an event, appeared to result from adaptive mechanisms that alter levels of memory activation and inhibition. Analysis of errors suggests that a similarity principle in goal substitution maintained foraging efficiency after 24-h retention intervals. Supported by Leakey Foundation, HD056352, and HD060563.