Commercial PSI apparatus was found to be convenient and practical; however, requiring clarification of methodology: (a) Change scores based on the same finger appear to be the only meaningful data; (b) Re-calibration of the densitometer is necessary with each print; (c) Dial readings should be made only after complete stabilization of the indicator, and; (d) all readings should...
First-order classical fear conditioning trials (tone paired with shock) were interspersed with second-order classical conditioning trials (light paired with the tone). Subsequently, Ss (rats) learned to escape the light by jumping a hurdle. Comparison of this performance with that of two control groups allowed the conclusion that fear was conditioned at the second order.
A progressive decrease in frequencies in the alpha range was observed during 14 days exposure to unpatterned light and white noise. Large individual differences, however, were present. Measures of CFF, depth perception, and size constancy were not affected and hallucinatory-like phenomena were rare. However, in several cases, long-lasting motivational losses were observed.
Multiple word associations to 52 CVCs were obtained from grade-school-aged children. Meaningfulness values (m) for each word, defined as the mean number of associations, were determined. While m values for the set of words increased with grade-age, the rank ordering of these values was essentially the same within each grade-age-sex group. Sex was not related to m values. Values...
Thirty Ss performed a 324-trial, subject-paced, two-signal, frequency-imbalaneed, disjunctive reaction time task. Responses on trials following the occurrence of the infrequent signal yielded longer RTs than responses on other trials. This effect is attributed to novelty produced “startle,” and is different from series effects previously reported.
Forty sessions of a procedure that yielded a constant rate of reinforcement for lever pressing IRTs of rats over the range 0-25 sec. led to a distribution of IRT probabilities over that same range that contained a minimum at about 3-6 sec, and a continuous increase in this probability at longer times. This failure to find a one-to-one correspondence between relative reinforcement...
The visual cliff was used to test the depth perception of monocular hooded rats when both texture density and depth were varied, when depth was varied but texture density held constant, and when Ss were kept in the dark after the eye was removed before being tested on the equal density condition. An additional group was tested for preference for “coarse” over “fine” texture...
Probe stimuli were introduced at 10 sec. and at 40 sec. in a one minute fixed interval operant conditioning paradigm. Data indicated disinhibition resulting from the 10 sec. probe. Some evidence for external inhibition was seen as a result of the 40 sec. probe.
Human Ss were given either 50 or 150 eyelid conditioning trials in the context of a probability learning task. No difference was found in the subsequent extinction rate of the two groups. This finding contrasts sharply with the effects of similar overlearning on the rate of extinction of the instrumental runway responses. The results are interpreted as further evidence that the...
Fifteen reactive and 15 non-reactive female rats were trained for 14 days (336 to 428 trials) on an escape-avoidance response in a shuttle box. The reactive group performed fewer avoidance responses, and contained a far greater proportion of animals which failed to learn the response or to respond at a reasonably high rate.
Following VI training to respond to a monochromatic stimulus, pigeons were tested for generalization in extinction with stimuli of shorter wavelength than the CS (uni-directional test) or with both shorter and longer wavelengths (bi-directional test). Regardless of test condition the gradients became reliably steeper during extinction; when gradients were equated for amount of...
Two experiments employing rats in the runway and intertriai reinforcement tested and confirmed the hypothesis that a given aftereffect remains functional until replaced by another aftereffect.
The present study dealt with paired-associate learning in elementary school age children as a function of associative strength and degree of competition. Two conditions were compared, each involving S-R pairs mediated by weak as well as strong associative strengths. The pairs mediated by strong associative strengths were identical in both conditions. In Condition I the S-R pairs...
Rats were trained on a two-valued auditory-intensity discrimination. Daily sessions consisted of 1 hr. of SD and 1, 2, or 5 hr. of sΔ. Discrimination performance was directly related to the amount of sΔ training. Any given amount of sΔ exposure was equally effective whether presented under massed or distributed conditions.
Rats were given shock-escape training in a 4 ft runway, then divided into 3 groups of 10 Ss each. During extinction one group received 1 ft of shock immediately after leaving the start box, a second group was shocked in the last 1 ft section of the alley, and a control group was never shocked. The immediate-shock group was found to be more resistant to extinction, followed...
One cat was taught to turn a wheel for milk reinforcement. During extinction of this habit the cat made significantly more responses while E was in the experimental room than when E was out. Possible determinants and implications of this effect are discussed.
Probability of opinion adoption and participation in problem solving was studied as a function of the type of social relationship between the pair of Ss (married couples, friends, and strangers) and as a function of E’s favoring the opinions of the male or the female in the pair through experimentally controlled success and failure feedback. The results showed that type of social...
Observation of GSR and judgments of shock intensity were obtained from nine Ss who received 10 presentations of each of seven shock intensities. Both GSR and judgments were significantly influenced by physical shock intensity. With physical intensity constant (statistically) the correlation between GSR and judgments was significantly positive for two Ss and significantly negative...
When hungry rats are reinforced with dry food for licking from a water trough, the resulting performances differ from those seen when other responses, such as bar pressing, are reinforced on the same schedules, in that thirst-motivated drinking intrudes on the food-reinforced pattern.
Studies of form discrimination have shown that children, rats, and octopus confuse figures which are left-right mirror-images more often than those which are up-down mirror-images. The generality of this finding was tested in an experiment with first grade children. When figures were presented side by side, as in other studies on children, earlier findings were confirmed. The...
The classical curve of recovery as a function of rest duration is increasing and negatively accelerated. The present study finds that this summary characterizes Rest 1 and cannot be generalized to Rest n successfully. The qualification is necessary for both work and learning tasks.
Two rhesus monkeys were trained by the correction method in a 70:30 red-blue discrimination under conditions in which they were required to earn each opportunity for choice. In subsequent phases of the experiment, the reinforcement-ratio was changed to 50:50, then to 30:70, and again to 50:50. In the 70:30 and 30:70 phases, both monkeys maximized. In the 50:50 phases they showed...
Rats were trained on a position discrimination. The experimental design involved simultaneously manipulating per cent and magnitude reward given for the correct response. Learning-rate was found to be a negatively accelerated growth function of reward magnitude for both of the reward schedules used. The results are interpreted as support for the treatment of reward magnitude as a...
Five squirrel monkeys were tested on delayed-response performance at delays of from 1 to 50 sec. Gradually increasing the delay durations did not yield performances that were much different from those where several delays were randomly presented within a session. Near-asymptotic performance was obtained after approximately 400–600 trials and the function describing performance at...
Ss performed fairly well at sequential number-averaging, but showed a definite recency effect. A model in which the response is a weighted sum of previous stimuli was supported, and an orderly serial position curve was obtained.