Response variation in instrumental extinction in rats with fornix transections

The present experiment examined spatial and response variation interpretations of the large difference in magnitude between operant and instrumental extinction deficits seen in hipocampally damaged animals. Latency measures and detailed behaviors of rats with fornix transections were compared to those of control rats during acquisition and extinction in an enriched spatial runway. Control rats, in comparison to rats with fornix transections, exhibited larger increases in start box, runway, and goal box latencies, but no spatial gradients were found. Control rats also exhibited less goal persistence and more response variation following the transition to extinction. The results suggest no fundamental difference between operant and instrumental deficits following hippocampal damage, but an interaction between strategies employed and traditional response measures.     

Factors affecting the measurement of classically conditioned fear in rats following exposure to escapable versus inescapable signaled shock.

Three experiments are reported in which rats first received 50 escapable or inescapable signaled-shock trials. Experiment 1 (n = 22) employed an acquired-drive paradigm and found inescapable shock subjects learned a hurdle-jump response to escape the signal less rapidly than did escapable-shock subjects. Experiment 2 (n = 24) employed a conditioned emotional response paradigm and found inescapable-shock subjects suppressed more when the signal was introduced in the appetitive bar-pressing task. Both experiments measured spontaneous activity immediately following conditioning and found no group differences. Experiment 3 (n = 39) employed the same activity task and found no difference between escapable- and inescapable-shock groups when the signal was introduced into the activity task. Both groups displayed less activity than a nonshock control group during the signal. The results suggest that lack of control over the shock in the conditioning phase did not result in an increase of conditioned fear. The results are discussed in terms of a learned active-inactive predisposition to respond.     

Reactions to Receiving Aid as a Function of Cost to Donor and Opportunity to Aid1

Drawing on equity theory, two possibilities that might reduce resentment of the donor following the receipt of aid which cannot be repaid were investigated: (a) the cost to the donor is minimized, and (b) the recipient has an opportunity to aid a third party. The results provide evidence that the recipient will like the donor less and be less willing to request future aid when he cannot repay the aid than when he can. Weak support was received by the hypothesis that the tendency to like the donor less when the aid cannot be repaid will be stronger, the greater the perceived cost. Support was found for the hypothesis that the decreased willingness to request future aid when the aid cannot be repaid will be stronger, the greater the perceived cost. Support was found for the hypotheses that the recipient will like the donor more and be more willing to request future aid when he has an opportunity to aid a third party than when he cannot aid anyone.     

Fixed-ratio and fixed-interval schedule control of matching-to-sample errors by children

Nine children, ages 4 through 7 yr, matched-to-sample on fixed-ratio, fixed-interval, variable-ratio, and variable-interval schedules of reinforcement. Simultaneous, zero-delay, and 2-sec delay matching were employed. Distributions of errors, in which the greatest number of errors occurred at the ordinal position immediately after reinforcement with fewer errors occurring at subsequent positions in the ratio, were produced by six of six children on fixed-ratio schedules for zero-delay and both of two children for 2-sec delay matching. Only two children of seven produced similar error distributions on simultaneous matching for fixed-ratio reinforcement. Variable-ratio schedules produced slightly lower accuracy for most subjects and no systematic error patterns for any subject. Error distributions occurred for all of the five children who experienced fixed-interval schedules for zero-delay matching. Peak error production occurred in the second fourth of the interval. Similar patterns were not produced on variable-interval schedules of equal reinforcement density. Schedule control of complex discriminated operants in children resembles control over similar responses of nonhuman animals.