P-2-22 Differentially signaling reward outcomes in pigeons 0. Bragason and S. Watanabe Keio University The purpose of this experiment was to systematically compare the relative strength of multiple vs. mixed terminal links and segmented vs. unsegmented terminal links while maintaining a constant rate of reinforcement across the two signaling arrangements. Pigeons were exposed to a concurrent-chains schedule with non-independent VI 30-s initial links and Results showed that when delays to food and timeout terminal-link outcomes ending in equal-probable 8-s of food and timeout. The trminal-link outcomes were signaled during one alternative but not during the other. Two terminal-link delays were tested: 15 and 30 s. was signaled, the pigeons preferred the signaled alternative, but when time passage during the delays to food and timeout was signaled, the pigeons showed a comparable preference for the unsignaled alternative. Preference was more extreme in the 30-s condition. The results indicate that signaling delayed outcomes within and between terminal links shifts preference away from indifference to the same degree but in the opposite direction. These results are in a qualitative agreement with conditioned reinforcement account. These findings have important implications for quantitative modeling of signal effects by suggesting that a successful account of one of the two signals provides an account of the other signal.

P-2-27 Efficiency of Tools and Flexibility of Chimpanzees in a Honey Dipping Task. Primate Research Institute, Kyoto University Maura Celli, Satoshi Hirata and Masaki Tomonaga Studies of tool-use in wild chimpanzees have shown cultural features, understanding of the environment and how selection of tools is acquired by learning, and also captive chimpanzees have been studied to test selectivity and learning processes. We tried to analyze comprehension of task demands, efficiency of materials and flexibility of subjects during experimental manipulation. Five females were tested, all with experience on the task and materials (40 available, 2 of each kind, not all suitable). After every two sessions with consumption, the mainly used material were removed. The removal of chosen tools was to observe sequence of choices and flexibility, and was kept until no honey was consumed (recoveries of consumption and tool choice were tested with all materials available). Not all chimpanzees were considered flexible, once their performance was more related with availability of efficient tools than exploring materials (loss of motivation after removal of favorite materials). Attempted insertion of improper materials and loss of proper tools inside the honey bottle were considered errors of concept and manipulation, respectively. These errors occurred even with previous experience, for all subjects, especially the more motivated ones, indicating the importance of it to learn and refine techniques, instead of a lack of recognition of task and materials. Errors were also analyzed as behaviors induced by the extinction of previous conditions (actions stimulus enhanced by the high levels of activity and absence of proper material conditions). Tool choice seemed more due to individual preferences than efficiency of materials, since in optimal conditions, subjects made different choices of ideal materials to perform the task.