Positive contrast following gradual and abrupt increases in reward magnitude using delay of reinforcement

In Experiment 1, rats were given a 1-pellet reward for 48 preshift trials. During a subsequent 20-trial postshift phase, one group was shifted to a 12-pellet reward on Trial 1, a second was shifted on Trial 11, and a third was given 1 more pellet each trial and then 12 pellets for the last 10 trials. The speeds of all three groups increased to a level above that of a control group given a 12-pellet food reward throughout training (positive contrast). In experiment 2, rats were shifted from 1 to 12 pellets either gradually or abruptly following either abbreviated training (9 trials) or extended training (20 trials). One group of control subjects received 12 pellets throughout training. The results revealed a positive contrast effect for gradually shifted subjects following extended training but not following abbreviated training. The abrupt shift procedure produced positive contrast following abbreviated training but only a marginal effect following extended training. These results indicate that, contingent upon the amount of preshift training, either gradual or abrupt reward increases may produce positive contrast.     

Effects of expectancies of different reward magnitudes in transfer from noncontingent pairings to instrumental performance

In two experiments, rats received noncontingent pairings of two stimuli with food reward, one paired with small reward and the other with large reward, and received bar press training with large reward or with small reward. When the noncontingent stimuli (NS) were presented for test during subsequent rewarded bar pressing and during early extinction of bar pressing, responding for each group was faster in the presence of the NS which was paired with the same reward magnitude that group received in bar press training than to the NS which had been paired with a different reward magnitude. As extinction progressed, all groups responded more slowly in the presence of the NS which had been paired with the large reward than in the presence of the NS which had been paired with small reward. These results were interpreted as indicating that responding in the presence of an NS depends on: (i) whether the reward expectancy elicited by the NS has been conditioned to the instrumental response, and (ii) the relationship between the reward expected in the presence of the NS and that received in test.     

Wilhelm Dilthey: Forerunner of humanist social thought

Humanist social thought is as a meadow in the forest of positivist science. Much of this space was cleared by Wilhelm Dilthey, not only through his attack on the fundamental assumptions of positivism, but also through his formulation of a critical method by which the works of free human consciousness could be understood. The first tenet of positivism is that the world is made up of ‘out there’ objectively knowable ‘facts’. Dilthey undercut this notion by asserting that the subject matter of the human studies was not mere facts of nature, but rather objectified expressions of the human mind. The second central assumption of positivism is that these facts are explainable or determined by general causal laws. In contrast, Dilthey asserted that, while we can explain the natural world, human action must be understood through an interpretive rather than a causal logic. In demonstrating and specifically describing such an interpretive procedure, Dilthey provided an epistemological and methodological grounding fur a humanistic science of the person and of the social world. His ideas illuminate the works even of his critics and his influence, though largely unacknowledged, continues to be widespread in all the human studies.     

Sex and coding strategy effects on reaction time to hemispheric probes

Two experiments were conducted to investigate the influence of coding instructions on cerebral laterality differences. Experiment I required 20 subjects (10 female) to use either rehearsal or imagery coding strategies in a recognition task with word probes to the right and left hemispheres. No hemispheric differences were found, but sex of subject was found to be related to coding strategy. Ten subjects (5 female) in Experiment II performed a similar task, except picture probes were used. Subjects using rehearsal coding responded faster to left-hemisphere probes, but faster to right-hemisphere probes when imagery coding was employed. The differing laterality effects in these experiments were attributed to naming responses implicitly required in Experiment II.     

The use of visual and name codes in scanning and classifying colors

The effect of incongruent color words on speed of classifying ink colors was measured in visual scanning tasks and in card sorting tasks. In both cases, little or no interference effects were noted when the classification allowed focusing on a single ink color or a set of highly similar colors (adjacent hues). Substantial interference occurred when the task required grouping of three dissimilar colors (nonadjacent hues). These findings suggest that the relative efficiency of name and visual codes in making perceptual classifications is largely dependent upon the memory requirements imposed by the task.     

Sequential search processes in long-term memory

In an experiment employing the symbol-element recognition task (Mohs, Wescourt, & Atkinson, 1975), subjects first learned six lists consisting of four words (elements) each. Each list was associated with a unique consonant (symbol). Subsequently, on each of a series of test trials, subjects were presented with one, two, or four symbol-element pairs. A positive response was required if all test words were correctly paired with their associated consonants and a negative response if any one test word was incorrectly paired with a consonant. Of primary concern was the way reaction time (RT) varied with number of pairs presented, the type of response required, and, on negative trials, the position of the mismatched pair in the test display. RT increased with the number of pairs presented on a trial and the increase was greater for positive than for negative trials. For negative pair trials, RT increased with the distance of the mismatched pair from the top of the test display. On negative trials in which the top pair in the test display was the mismatched pair, RT increased with the total number of pairs presented on the trial. A serial, probabilistic order of processing model is proposed to account for these results, and applications of the model to other paradigms are discussed.     

The effects of stress on state and trait anxiety in emotionally disturbed,normal, and delinquent children

The effects of stress on trait and state anxiety of emotionally disturbed, normal, and delinquent children were assessed using the State-Trait Anxiety Inventory for Children (STAIC). This scale measures both transitory feelings of apprehension and tension that vary over time as a function of situational stress (A-State) and individual differences in the disposition to experience such anxiety states (A-Trait). Results indicated that A-State increased as a function of stress, whereas A-Trait was relatively stable and impervious to the temporary effects of stress. Use of the STAIC with normal and deviant populations was supported.