Probability learning as a function of momentary reinforcement probability

Pigeons were trained on a probability learning task where the overall reinforcement probability was 0.50 for each response alternative but where the momentary reinforcement probability differed and depended upon the outcome of the preceding trial. In all cases, the maximum reinforcement occurred with a “win-stay, lose-shift” response pattern. When both position and color were relevant cues, the optimal response pattern was learned when the reinforcement probability for repeating the just-reinforced response was 0.80 but not when the probability was 0.65. When only color was relevant, learning occurred much more slowly, and only for subjects trained on large fixed ratio requirements.     

Incidental learning as a function of anticipated task difficulty

Three experiments were conducted to demonstrate the effects of motivational arousal, due to anticipated task difficulty, on retention of familiar and unfamiliar incidental materials. Brehm, Wright, Solomon, Silka, and Greenberg (1983) have provided evidence that motivational arousal in immediate anticipation of a task is a nonmonotonic function of task difficulty, with difficult tasks producing a relatively higher level of motivational arousal than easy or impossible tasks. It was predicted that increased motivational arousal would facilitate retention of incidentally presented familiar materials (presumably more easily retained) and interfere with retention of incidentally presented unfamiliar materials (presumably less easily retained). In Study 1, subjects anticipating either an easy or a difficult task were exposed to familiar and unfamiliar first names. The predicted interaction between task difficulty and familiarity on recall of the first names was reliably supported. In Study 2, an impossible task condition was added. The results indicated that an effective impossible condition had not been created. In a third study designed as a procedural modification of Study 2, the predicted nonmonotonic interaction was found. Theoretical implications are discussed.These experiments were ably conducted by Ralph Young, whose help is gratefuly acknowledged. We would like to express our gratitude to Jack Brehm for invaluable suggestions concerning this research.     

Rate of addition as a function of difficulty and age

Rate of addition was studied as a function of difficulty as measured by problem length. The hypothesis was tested that the rate of addition would decline as a function of the logarithm of the number of addition operations per problem. The test material required the rapid addition of single columns of digits ranging from two to twenty-five digits in length. Rate of uncorrected addition declined as a power function of problem length and the rate of correct addition declined as an exponential function of length. Results indicated that subjects who varied in age and mental status could be differentiate according to the parameters defining the curves of addition rate as a function of length.The cooperation of the staff of the Baltimore City Schools, the cooperation of the staffs of the Spring Grove and the Springfield Maryland State Hospitals and the Sheppard and Enoch Pratt Hospital, the assistance of Miss Charlotte Fox in devising the test material and gathering some of the data, and the computational assistance of Mrs. Betty Benser are gratefully acknowledged.