One electroconvulsive shock (ECS) administered at various times after a learning experience was used to evaluate the completeness of post-trial fixation at several times subsequent to learning. The susceptibility of traces to ECS decreases only after an extended period, but once the decrease is initiated complete protection occurs rapidly. This interval of trace susceptibility is...
It was noted that the most frequently used method of measuring brain lesions is probably the planimeter. The planimeter method is time consuming and planimeters are not readily available to most psychologists. The dot grid method was described and recommended for its savings in effort and expense with negligible sacrifice of accuracy.
The heart rates of food-deprived humans did not increase over their control rates.
An eight-pair PA list of low-meaningfulness paralogs was learned to a criterion of two successive errorless trials by two groups of Ss, one of which articulated the stimuli while the other did not. All Ss then learned the same pairs in the backward direction for 16 trials, half of each group articulating the stimuli. Stimulus articulation had no effect on first-list learning...
Rhesus (Macaca mulatta), Philippine cynomolgus (M. irus), and stump-tailed(M. speciosa)macaques were given the same 16-step pretraining procedure in a Wisconsin General Test Apparatus (WGTA). The stump-tailed monkeys completed pretraining in significantly fewer trials than did the rhesus and Philippine monkeys. The pretraining performance of the latter two species was about the...
The copulatory behavior of three groups of sexually experienced male hamsters was observed after androgen withdrawal. Each group was given four tests spaced five days apart: Group I began 45 days, Group II 60 days, and Group III 75 days after hormone removal. Amount of copulatory activity was found to be similar for all groups. In experienced males, the reduction of sexual...
Twenty Ss were given 60 reinforced trials to a positive CS and 60 non-reinforced trials to a negative CS on each day for five days. An increase in frequency of CR to both CSs but no discrimination was found on Day-1. On Day-2, performance to both CSs levelled off and discrimination began. On Days 3–5, discrimination improved between but not within daily sessions. With each of...
An experiment, using rats in a runway, demonstrated that resistance to extinction is affected by the patterns of delayed reinforcement imposed during training.
In a two-compartment grid shuttle box, rats tended to prefer a 1/2 sec. or a 5 sec. warning signal over no signal preceding unavoidable shock. They did not prefer either a 0 sec. or random signal-shock interval over no signal. And they did not tolerate more shock to obtain a signal than they had to tolerate in a no-signal compartment.
Hooded rats were placed on a center board with a plain surface (black or white) under glass on one side and a black and white striped pattern (parallel or perpendicular to the center board) under glass on the other. Striations of 1/4 in, 1/8 in and 1/16 in were used. Ss descended from the center board to the 1/4 in and 1/8 in stripes significantly more frequently than to the...
The amnesic effect of electroconvulsive shock has been explained in terms of consolidation theory and in terms of interference hypotheses. Crucial evidence is not yet available for choosing between these alternative explanations, and it appears that many variables (including the nature of the response measure used and the number of seizures administered to the S) influence the...
Standard procedures were used to shape the bar-pressing avoidance response in a rhesus infant within the first month of life. By overlapping the last second of a 15-sec. tone with shock, termination of the tone was eventually sufficient stimulus change to reinforce successive approximations to the bar-press response. Eight sessions of 1 hr. or less, given over a 12-day period...
Twenty-one comparisons of activity differences among C57, DBA and C3H strains of mice have appeared over the past 11 yr. Despite wide variations in the use of substrains, experimental techniques and testing devices, strain rank order remains statistically stable. Such uniformity may indicate well-buffered physiological correlates.
A description is provided of a pellet dispenser that automatically reinforces a rat on each trial with an amount of food that is directly proportional to the speed with which the rat has traversed a runway. Preliminary data indicate that Ss reinforced on such a speed-contingent basis run significantly faster and are less variable than yoked controls.
Although the results were not statistically significant, a group of rats trained by a naive experimenter showed (a) less food intake, (b) greater loss of body weight, and (c) fewer trials to learn a maze. However, the maze running time of the naive experimenter’s rats was significantly slower than that of the other experimenter’s rats.
Three pigeons were trained on a variable-interval schedule. Following this, they were extinguished. During extinction, 1-min. periods of time-in (TI) and time-out (TO) alternated. The Ss responded only in TI. When extinction was complete, TO was removed in the middle of a session. All Ss begain responding shortly after the removal of TO.
The possibility of erasure or partitioning in short-term memory was studied by instructing Ss to retrieve by free recall only 10 relevant letters embedded in a sequence of 20 visually presented letters. In the pre-cuing condition, irrelevant letters were indicated by a preceding blank, while in the post-cuing condition, irrelevant letters were indicated by a following blank...
Postparturitional rats when given a choice of either an experimentally treated (hypothermia and rotated) or a control neonate, significantly preferred the control. Experimental treatment of one half the litter disrupted maternal retrieving scores for all offspring. The results suggest that early experience studies may have a serious confounding variable.
Detections, false responses, and latencies were measured in a 1-hr. auditory vigilance task following ingestion of either a stimulating drug, one of two tranquilizers, or a placebo. Changes in performance under the placebo were explicable in terms of shifts toward conservatism in S’s criteria for responding; under the tranquilizers, similar shifts in criteria occurred as well as...
A modified learning task in which each problem contained recurrent and nonrecurrent stimulus forms was administered to age groups 6, 8, 10, and 12 years. For each age group a correct choice based on the nonrecurrent stimuli was more difficult than a correct choice based on the recurrent stimuli.
Two Ss identified pairs of 15 msec. one-bit auditory and visual stimuli when the interval between the stimuli varied from 0 to 500 msec. The auditory judgments were better when the auditory and visual signals were separated by 500 msec. than when the two signals were presented simultaneously, and were also better when the auditory stimulus followed the visual stimulus than when...
Two experiments were run using either circles of different diameters or lines of different lengths as stimulus terms in PA learning. Those responses associated with the stimuli at the end positions of the stimulus dimensions of circle diameter and line length were learned first, producing the serial position effect. Analyses of intrusions supported a stimulus generalization...
A theoretical model is proposed for the interaction of the effect of number of training trials and magnitude of reward on speed of reversal learning. The model was tested by an experiment involving 2 levels of reward magnitude and 4 degrees of training. An overlearning reversal effect was obtained under large reward but not with small reward. The data from the 8 groups of rats...
Pigeons were trained in series of discriminative problems with stimuli differing both in color and shape, one dimension relevant and the other irrelevant in each problem. An ORE for shape appeared late in the experiment, but color-reversal was retarded by overtraining. Overtraining. on shape retarded shift to color, but overtraining on color had no effect on shift to shape. Where...