Some features of the after-contraction phenomenon

The well-known unintentional muscular contraction following a voluntary contraction was found to be inhibited by instructions favouring relaxation, to be increased by a difficult concurrent task and to be superimposed on small voluntary contractions of the same muscles. It was not superimposed (in either sense) on antagonist contractions. An explanation is suggested, based on the interaction of sensory adaptation and some other process known to occur and apparently related to fatigue.     

Inter-reinforcement times for the bar-pressing response of white rats on two DRL schedules,

A knowledge of inter-reinforcement times (IS^RT) seems of interest because, among other reasons, they bear on the variable of “reinforcement density” in behavior theory. IS^RT data were here recorded for bar-pressing responses by two white rats working on DRL 10 sec and DRL 40 sec. Sample inter-response time (IRT) distributions and cumulative records were taken simultaneously for comparison purposes. IS^RT sequences and distributions have certain characteristics that urge further investigation.     

Some observations and measurements of the Pulfrich phenomenon

The Pulfrich pendulum was evaluated as a potential screening device for the detection of anomalies of binocular vision. For this purpose, a booth was set up at the Kentucky State Fair (1964) and the general public invited to observe the pendulum and record their responses with the equipment provided. The obtained results indicate that a dichotomy can be achieved between those who have binocular vision and those who do not. However, gradations of binocular vision from poor to good cannot be achieved with the pendulum as presently understood. Contrary to explanatory theory the characteristic shape of the seen pendulum path was asymmetrical following the rule that the path was displaced away from the observer on the side of the filtered eye.     

Some observations and measurements of the Panum phenomenon

The angular separation between the “binocular” and the “monocular” line of Panum’s limiting case was systematically varied under conditions in which the changes in seen relative depth could be quantified. Stereoscopic, equidistant, and anomalous depth localizations were seen. A criterion of variability of depth localization was utilized to differentiate the mechanism operative in determining the seen depth. When stereopsis is clearly present, depth in Panum’s limiting case is predictable and reveals a one-to-one relationship with the angle of lateral separation of the stereoscopic stimuli, i.e., the odd line cooperates in free binocular vision with both of the paired lines to give “true” stereoscopic depth. The range of angular separation over which Panum’s limiting case will give rise to stereoscopic depth is increased by free eye movements well beyond the usually reported limits of Panum’s retinal areas.     

Some variables in the blue (red) phenomenon

The relation between spontaneous color choices and ratings of the prototypicality, conspicuousness, and pleasantness of colors was studied in a sample of Dutch college students. Pleasantness, not prototypicality or conspicuousness, determined the four most frequent spontaneous choices--red, blue, green, and purple. Subjects considered blue the most pleasant of the 12 colors studied, which suggests a pleasantness explanation for the "blue phenomenon" found in some countries. The predominance of red as a spontaneous choice replicated the results of previous studies in the Netherlands. Red also was rated highest in prototypicality but was not rated higher by red choosers than by choosers of other colors, so that a simple prototypicality explanation was rejected. Further analysis showed that the predominance of red as the spontaneous choice of Dutch subjects can be explained by an interaction between prototypicality and pleasantness: Subjects tended to choose red when they rated it highly on both variables.     

Some sources of variance in skin conductance

An attempt was made to identity some of the factors that might contribute to the variance associated with skin conductance. Results confirmed earlier findings that Blacks have lower levels of skin conductance than Caucasians. The precise role of skin albedo is difficult to determine because within these groups there appears to be a negative relationship between skin reflectance and skin conductance. Possibly peripheral blood flow differences are responsible. There were no differences in heart rate or in self-report measures of arousal between the groups, and the contribution of personality variables to skin conductance variance was, in part, anomalous.     

The effect of rearing environments on the contrafreeloading phenomenon in rats

Eight naive rats were reared in enriched or impoverished environments for 39 days after weaning and then lived in operant chambers, in which they could obtain food pellets freely or by lever pressing, for 25 or 30 days. The animals raised in an impoverished environment acquired the bar-press response quickly when placed in the operant chambers and maintained a preference for obtaining food via bar pressing. Animals raised in an enriched environment did not learn to lever press, as demonstrated by low levels of responding and the lack of bar pressing when free food was subsequently removed. It was concluded that restricting animals' postweaning environments facilitated learning in a choice situation, probably because of increased activity levels. The results are interpreted in relation to previous studies on rearing environments and on contrafreeloading.     

The physical properties of bar-pressing behaviour and the problem of reactive inhibition

Many of the terms used in the literature on reactive inhibition are vague, subjective or incorrect. The weighted bar is not a suitable device in the study of this problem, since it records irrelevant aspects of behaviour. An experiment using apparatus which gives a continuous record of the force which a rat applies to a knob produces the following results. After much practice, pressing becomes sharp and brief and the amount of activity per reward is reduced. Under conditions of no (intentional) secondary reward the amount of activity during extinction is at first positively correlated with the average activity per reward during training, but the correlation diminishes as extinction proceeds. With auditory secondary reward there is no correlation.     

Some sources and consequences of career exploration

The present research investigated (a) factors that may influence participation in career exploration, and (b) the role of anxiety in the exploration process. The sample consisted of 161 undergraduate college students. Work-role salience (the importance of work in a person's life) was positively related to participation in self-related and work-related exploration. Self-related exploration was positively related to satisfaction with the occupational decision of low anxiety students and was negatively related to satisfaction among high anxiety students. Furthermore, dissatisfaction with an occupational decision was more likely to stimulate future work-related exploration for low anxiety students than for highly anxious students. The implications of these findings for the career exploration process were discussed.     

All-or-none bottleneck versus capacity sharing accounts of the psychological refractory period phenomenon

The goal of the present experiment was to test the predictions of Central Bottleneck and Central Capacity Sharing models. According to the Central Bottleneck model, dual task interference, as observed in the PRP paradigm, is caused by an all-or-none bottleneck in information processing. The Central Capacity Sharing model postulates that dual task interference is caused by a capacity limited process that can allocate capacity in a graded fashion. The Central Bottleneck model predicts no change in RT1 with decreasing SOA, whereas the Central Capacity Sharing model predicts that RT1 will increase with decreasing SOA and that the slope of the RT1 SOA effect will depend upon the difficulty of task 2. Subjects were required to perform a tone pitch judgement and shape-matching task in rapid succession. Task order was randomized and the SOA between the first and second stimulus varied from 50 to 1250 ms. Results from this experiment favour the Central Capacity Sharing model. The results were then run through simulations of both the Central Bottleneck and Central Capacity Sharing models. Results from the simulations also favoured the Central Capacity Sharing model. As the difficulty of the second task increased, more capacity was allocated to it, confirming the prediction that as task 2 difficulty increases, the RT1 SOA slope increases. The proportion of capacity allocated to the first task varied from.78 to.91 indicating that capacity can be allocated in a graded fashion.