Cross-modal transitivity in a California sea lion (Zalophus californianus).

The ability of an experimentally experienced female California sea lion to form transitive relations across sensory modalities was tested using a matching-to-sample procedure. The subject was trained by trial-and-error, using differential reinforcement, to relate an acoustic sample stimulus to one member from each of two previously established visual classes. Once the two auditory-visual relations were formed, she was tested to determine whether untrained transitive relations would emerge between each of the acoustic stimuli and the remaining stimuli of each 10-member visual class. During testing, the sea lion demonstrated immediate transfer by responding correctly on 89% of the 18 novel transfer trials compared to 88% on familiar baseline trials. We then repeated this training and transfer procedure twice more with new auditory-visual pairings with similar positive results. Finally, the six explicitly trained auditory-visual relations and the 56 derived auditory-visual relations were intermixed in a single session, and the subject's performance remained stable at high levels. This sea lion's transfer performance indicates that a nonhuman animal is capable of forming new associations through cross-modal transitivity.