The overshadowing and blocking of punishment

Two experiments were undertaken to test the assumption that the outcome of an instrumental contingency depends on the acquisition of signalling properties by the response in the same sense that the acquisition of signalling properties by a stimulus is viewed as determining the outcome of a Pavlovian contingency. The presence coincident with a punished response of a stimulus either previously or preferentially correlated with shock was found to reduce the extent to which punishment suppressed the rate of responding. It was argued that these results, interpreted as indicating the blocking and overshadowing of the response-shock association, were consistent with the assumption tested.     

Response bias and the measurement of choice alternation

The problem of devising a measure of alternation of choices that is independent of response bias is considered. Previous solutions are equivalent to the correction for chance guessing in the Yes/No experiment of psychophysics, and require an estimate of response bias, usually from choices on the first of two daily trials. This involves the questionable assumption that response bias is homogeneous over time or across subjects. It is suggested that spontaneous alternation is analogous to the two alternative forced choice situation of psychophysics, and the fourfold point correlation is proposed as an index of alternation that is statistically independent of response bias. Implications for interpreting the effect upon spontaneous alternation of hippocampal and other lesions are considered.     

Sequential effects of non-reward in a skinner box

The partial reinforcement extinction effect was examined within subjects in a simultaneous discrimination in a two bar Skinner box. Discrete trials were used, rats being required to press the bar under the illuminated cue light; one bar was correlated with 100% the other with 50% reinforcement. The three groups differed in the probability of a change in the cue light between trials during acquisition. When this probability was low, the 50% bar was preferred in extinction, while when it was higher (0.433 or 0.875) the 100% bar was preferred. These results confirm Capaldi's (1966) hypothesis of the partial reinforcement extinction effect, and support a suggested explanation of some conflicting results on partial reinforcement effects in a Skinner box.     

Conditioning of striatal dopamine metabolism with methadone,morphine or bulbocapnine as an unconditioned stimulus

Psychotropic drugs such as methadone, morphine and bulbocapnine produce increments in dopamine metabolism as an unconditioned reflex. When a buzzer noise is used as a conditioned stimulus (CS) with these drugs as unconditioned stimuli, the buzzer CS acquires the properties of the drugs in increasing dopamine metabolism. These results suggest that the brain, like other visceral organs, can be conditioned in terms of neurotransmitter release or metabolism.     

Acquired aphasia in children and the ontogenesis of hemispheric functional specialization.

We have described a series of 26 cases of cortical lesions in children from $\text{3}\text{1}\text{2}$ to 15 years of age (17 left-sided, six right-sided, three bilateral), in which 19 had varying degrees of language disturbance. We have attempted to establish the nature and evolution of these aphasic disorders, and have compared our observations to those previously published. Our analysis appears to indicate a relative hemispheric equipotentiality which permits the transfer of language representation to the opposite hemisphere in the case of a unilateral lesions in childhood. This conclusion, however, has at least the appearance of being in conflict with other reported findings, viz., those deriving from psychometric testing of subjects with unilateral perinatal lesions; and those concerning studies of fetal and newborn brains which suggest a very early, if not innate, hemispheric specialization.The fact of this discrepancy has lead us to reconsider the concept of a critical period as defined by Lenneberg. In this respect, we have also discussed the possibility of a partial transfer of language representation, of an intrahemispheric reorganization by intact “uncommitted” areas (P. Goldman), and finally, the need for an adequate stimulus during a given period in order for a preformed area to become functional.