Blocking and overshadowing between visual spatial cues in the toad Bufo arenarum.

DANERI, F., CASANAVE, E. B. & MUZIO, R.N.

Buenos Aires

Congreso; XIVth Biannual Meeting of the International Society for Comparative Psychology.; 2008

International Society for Comparative Psychology (ISCP, USA)

Spatial learning allows amphibia, as well as other vertebrates, to localize shelter and food, remembering this information and return to those places months later. We are analyzing the biological mechanisms that rule this learning, looking for common patterns with other vertebrates, potentially present in a common ancestor. The goal of this study was to determine if the blocking and overshadowing effects, well documented in mammals and birds, were present during spatial learning in the toad Bufo arenarum. Two experiments were conducted where animals were trained to localize a reinforcer (water) using visual cues placed on the wall of an open field. On the first experiment we observed that the presence of a second visual cue can cause animals to use less a first one than they would have used if trained on it alone (showing an overshadowing phenomenon). On the second one a blocking effect was observed, the prior presentation of one element of a compounded visual cue reduces or blocks the learning about the second component of the cue. These results show that blocking and overshadowing are generalized basic phenomena present in a wide variety of vertebrates (including mammals, birds and amphibians), potentially modulated by a common ancestral process.