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.