KNOWING BEFORE DOING: DISCRIMINATION BY RATS OF A BRIEF INTERRUPTION OF A TONE

Eight rats' lever presses were reinforced after an interruption in a tone, provided the lever had not been pressed before the tone interruption. After a few sessions, long before the animals reliably refrained from lever pressing before the interruption, the latencies of postinterruption presses (time from the termination of the interruption to the moment of the lever press) dissociated into two classes: short ones for to-be-rewarded presses, and long ones for presses in the other trials, which contained no reward because one or more lever presses had occurred before the interruption. Thus discrimination of impending reinforcement in the current trial occurred before there was evidence of sensitivity to reinforcement in the reinforcement-producing aspect of behavior. This finding is related to Shimp's (1981) contention that the temporal properties of recent behavior are reinforceable, if remembered. The present finding shows that learning to discriminate whether one's behavior has met a contingency, and learning to carry out this behavior, need not go together, implying that memory of temporal properties is probably a necessary but not a sufficient condition for learning the latter.     

ON THE SIGN OF SLOPE IN THE LEARNING OF LINEAR FUNCTIONS

Three groups of subjects were presented with pairs of values ( E and S ) of three different linear functions E = a+bS. In a test phase they had to indicate the E -values that corresponded to the S -values. The values were represented as distances marked on straight lines. Two groups, one a control group, had a positive slope, the third group a negative. The squared sum of the S-E differences was kept constant. All groups had roughly the same performance as measured by the squared sum of deviations from empirical and correct E -values. The learning curves indicated, however, that some learning had taken place in the group with the negative slope. It was concluded that a principle rather than a function was learned.