Experimental analysis of academic performance in a classroom setting

We evaluated the effects of specific stimulus prompts on accuracy of academic performance with adolescents who displayed academic problems in a public special education classroom. We conducted analyses of instructional strategies within a multielement design with two students who had mild disabilities. Differential effects of the strategies on reading comprehension were not apparent on demand (independent-level) tasks but were apparent on high-demand (instructional-level) tasks. These results suggested that the application of experimental analysis methodologies to instructional variables may facilitate the identification of stimulus prompts associated with accurate academic performance.     

Dexamethasone Does Not Prevent Seven-Day ADX-Induced Apoptosis in the Dentate Gyrus of the Rat Hippocampus

Long-term adrenalectomy (ADX) is known to result in apoptosis within the dentate gyrus of the rat hippocampus. While the underlying mechanism is still unclear, adrenal steroids appear to play a pivotal role in granule cell survival, as administration of the mineralocorticoid receptor (MR) agonists, corticosterone and aldosterone, to ADX rats results in protection against the ADX-induced effect. The consequence of administration of the glucocorticoid receptor (GR) agonists, dexamethasone and RU28362, however, is less clear, and either complete or only partial protection for the ADX animal has been reported. This study investigated further the role played by GR in the degenerative process. After establishing the characteristics of seven-day ADX-induced apoptosis in the young male Wistar rat, the effect of chronically-implanted, subcutaneous pellets containing various doses of dexamethasone and corticosterone, on ADX-induced apoptosis was studied. Both high and low doses of corticosterone were found to be protective. In contrast to some other studies, however, neither dose of dexamethasone had any obvious protective effect and rather seemed to increase apoptosis in dentate gyrus of intact animals. Intracerebroventricular infusion of dexamethasone for seven days was also found to be ineffective in preventing apoptosis, demonstrating that it is occupation of MR, rather than GR, which is crucial to dentate gyrus granule cell survival.     

Mood variability and the intensity of depressive states

Little is known about the relationship between the variability of moods and the tendency to experience depressed mood. The moods of twenty-five student subjects were measured over a period of some 30 days using scales assessing positive affect and negative affect. An index of mood variability was computed. This was correlated with two measures of average level of depression. The results showed a strong correlation between variability of moods and level of depression. High levels of mood variability accompanied high levels of depressive state in this nonclinical sample.     

Mental transformations in the identification of left and right hands.

Subjects determined as rapidly as possible whether each line drawing portrayed a left or a right hand when the drawings were presented in any of four versions (palm or back of either hand) and in any of six orientations in the picture plane. Reaction time varied systematically with orientation and, in the absence of advance information, was over 400 msec longer for the fingers-down orientation. However, when subjects were instructed to imagine a specified (palm or back) view of a specified (left or right) hand in a specified orientation, reaction times to test hands that were consistent with these instructions were short (about 500 msec), independent of orientation, and unacompanied by errors. It is proposed that subjects determine whether a visually presented hand is left or right by moving a mental "phantom" of one of their own hands into the portrayed position and by then comparing its imagined appearance against the appearance of the externally presented hand.     

The effect of a low rate of regular signals upon the reaction times of introverts and extraverts

In an RT (reaction time) task involving responding to infrequent, regular signals, extraverts produced higher proportions of missed signals and lengthened RT's than introverts did. This result was only obtained after some time on task and is evidence that inhibitory states are formed more rapidly in extraverted subjects under low stimulation conditions. In a more extended version of the task, mean RT was found to be longer in extraverted than introverted subjects in the second half of the experiment though there was no significant difference between the groups in the first half. These findings are complementary to data from previous studies showing that extraverts generate stronger inhibitory potential in continuous responding tasks, or that their characteristic arousal level may be lower than that of introverted subjects. The need to distinguish between the different explanatory constructs is discussed and a simple model amalgamating the major theoretical positions is outlined.     

Contingent feature analysis in speech perception

A contingent adaptation effect is reported for speech perception. Experiments were conducted to test the effects of an alternating sequence of two adapting syllables, [da] and [t^hi], on the perception of two series of synthetic speech syllables, [ba]-[p^ha] and [bi]-[p^hi]. Each of the test series consisted of 11 stimuli varying in voice onset time, a cue which distinguishes voiced from voiceless stop consonants in word-initial position. The [da]-[t^hi] adapting sequence produced opposite shifts in the loci of the phonetic boundaries for the two test series. For the [ba]-[p^ha] series, listeners made fewer identification responses to the [b] category after adaptation, while for the [bi]-[p^hi] series, listeners made more responses to the [b] category. The opposing shifts indicate that the perceptual analysis of voicing in stop consonants is carried out with respect to vowel environment.     

The nonverbal mediation of self-fulfilling prophecies in interracial interaction

Two experiments were designed to demonstrate the existence of a self-fulfilling prophecy mediated by nonverbal behavior in an interracial interaction. The results of Experiment 1, which employed naive, white job interviewers and trained white and black job applicants, demonstrated that black applicants received (a) less immediacy, (b) higher rates of speech errors, and (c) shorter amounts of interview time. Experiment 2 employed naive, white applicants and trained white interviewers. In this experiment subject-applicants received behaviors that approximated those given either the black or white applicants in Experiment 1. The main results indicated that subjects treated like the blacks of Experiment 1 were judged to perform less adequately and to be more nervous in the interview situation than subjects treated like the whites. The former subjects also reciprocated with less proximate positions and rated the interviewers as being less adequate and friendly. The implications of these findings for black unemployment were discussed.