TIMING ABILITY AND NUMERICAL COMPETENCE IN RATS

Counting and timing ability in Wistar rats was tested in 4 psychophysi cal choice experiments. After training naive rats with discrete sound sequences that confounded time and number, only time gained control of behavior; control by time was stronger and acquired more rapidly afte r training with separate time-and number-relevant signals. Two nonnume ric cues associated with periodic sequences, temporal ratio and sequen ce pattern, did not appear to provide the basis for numerical discrimi nation, as performance was unaffected by a sudden change from periodic signals to signals with unique temporal patterns. Even after highly a ccurate performance with number, time showed exclusive control of beha vior for signals with conflicting time and number cues. This study pro vides an unequivocal demonstration that rats can count, but they do so according to H. Davis and J. Memmott's (1983) ''last resort'' hypothe sis.