Visual discrimination learning in the fire-bellied toad Bombina orientalis.

This study explored the visual discrimination learning ability of fire-bellied toads (Bombina orientalis). Two groups of toads were trained in a simultaneous visual discrimination task involving video footage of either black crickets on a white background (black-cricket toads) or white crickets on a black background (white-cricket toads). Fifteen widely spaced acquisition trials were followed by 12 reversal trials. Successful learning wasobserved by decreased incorrect snapping and reduced latency to snap at the correct stimulus (S⁺) during acquisition; however, white-cricket toads executed significantly more incorrect snaps than did black-cricket toads. Both groups of toads could master the reversal task as measured by latency to snap at S⁺, but not as measured by the proportion of incorrect snaps. Despite the stronger potency of the black-cricket stimulus, the results showed that toads can learn a simultaneous discrimination task and a reversal of its contingency. This elaborate form of learning appears to be conserved among vertebrates.