Abstract # 2647 Event # 21:

Scheduled for Saturday, September 19, 2009 09:30 AM-09:40 AM: Session 3 (Del Mar Room) Oral Presentation


SEQUENCING PERFORMANCE AND ERROR TRENDS IN ZOOLOGICALLY-MANAGED GORILLAS (GORILLA GORILLA GORILLA) AND CHIMPANZEES (PAN TROGLODYTES)

K. E. Wagner and S. R. Ross
Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, 2001 North Clark Street, Chicago, Illinois 60614, USA
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Experimental evidence of serial learning abilities is evident for a variety of primate species. Much work has been conducted in laboratory settings with a range of protocols. As such, there are few opportunities for direct species comparisons using identical methodology. In the current study, two zoo-living chimpanzees and three gorillas used a computerized touchscreen interface to sequence 3-, 4-, and 5-item lists of arbitrary stimuli. Gorilla subjects performed more accurately [F(1,944)=149.12, p<0.001] and exhibited longer response latencies [F(1,944)=89.16, p<0.001] than chimpanzees across lists. Subjects produced a shorter response time at higher ordinal positions [F(4,2500)=822.09, p<0.001] but only gorillas showed a decrease in overall latency with increased list length [F(2,534)=48.34, p<0.001]. Subjects most frequently erred by selecting the symbol associated with the next ordinal position [F(3,3564)=902.18, p<0.001]. Additionally, more first position errors were made in longer lists compared to shorter lists [F(2,1664)=180.59, p<0.001]. Results indicate that individuals of both species are capable of successfully ordering abstract symbols in consistent sequences. Performance and error differences between species were likely influenced by combined species- and individual traits including age, social status and reactivity. Patterns of error are consistent with a position-association strategy, rather than a serial-search strategy. These results 1)demonstrate a comparable sequencing ability across ape species; 2) support laboratory-findings of a primate-typical sequencing strategy and 3) confirm the feasibility of cognitive research in a zoological setting.