Number Tags Applied by Rats to Reinforcers are General and Exert Powerful Control Over Responding

Abstract

Rats are capable of employing the number of successively presented food reinforcers in a runway as a discriminative cue. Trained, for example, under a series in which three food-reinforced trials precede a non-reinforced trial (RRRN), rats have run fast to R, R, and R, slowly to N. Such numerical discriminations have been shown to be general to some extent, being maintained in connection with either novel reinforcers suddenly introduced, or various alterations of the old series of reinforcers. In the two investigations reported here, the four-event series R'RRN was employed, R’ and R being qualitatively different reinforcers. On being shifted to more severe alterations of this series than heretofore, the previously established numerical discrimination was maintained, indicating that the number tags rats apply to reinforcing events are to a considerable extent general. In Experiment 1 rats trained under the two series R'RRN and RRN maintained the numerical discrimination when shifted to the series R'RN and NR'RN, despite the fact that the specific events R'R that signalled R in original training (R'RRN series) now signalled N in the shift or transfer phase. In Experiment 2 rats trained under R'RRN and RRN maintained the numerical discrimination on being shifted to the series NRRRN and RRRN (count to three), despite the fact that they had previously received the RRN series (count to two). Various other findings obtained here are consistent with the view that the rat's number tags are to a considerable extent general.