Performance of humans in concurrent avoidance/positive-reinforcement schedules

Performance maintained under concurrent schedules consisting of a variable-interval avoidance component and a variable-interval positive-reinforcement component was studied in three human subjects using points exchangeable for money as the reinforcer. The rate of responding in the avoidance component increased, and the rate of responding in the positive-reinforcement component declined, as a function of the frequency of point-losses avoided in the avoidance component. The performance of all three subjects conformed to equations proposed by Herrnstein to describe behavior in concurrent schedules. The logarithms of the ratios of the response rates in the two components, and the logarithms of the ratios of the times spent in the two components, were linearly related to the logarithms of the ratios of the frequency of loss avoidance in the avoidance component to the frequency of reinforcement in the positive-reinforcement component. When a changeover delay of 5.0 sec was imposed, the slopes of the linear functions were close to 1.0 in the case of two subjects, whereas the third subject exhibited significant undermatching. For two subjects the changeover delay was then reduced to 2.0 sec; in both cases the slopes of the linear functions were lower than under the 5.0-sec condition. One subject participated in a third phase, in which no changeover delay was imposed; there was a further reduction in the slopes of the linear functions.     

The acquisition of observing.

Pigeons were exposed to stimuli correlated with the presence or absence of a variable-interval 60-second schedule of reinforcement only while they depressed a crossbar or "perch." In the first experiment, the stimuli were different tilts of a line displayed on the key. When the difference in brightness between the line and the background (salience) was maximal, seven of eight birds acquired the discrimination, but when the difference was reduced by 50%, only one succeeded. In the second experiment, wavelength of chamber illumination served as the relevant dimension. Neither experiment showed a large effect attributable to the magnitude of the difference (disparity) between the positive and the negative stimulus. Individual differences in time spent observing were positively correlated with level of discrimination in the presence of the stimuli. All birds produced the positive stimulus for a greater proportion of the available time than they did the negative stimulus. This may be the mechanism that provides selective reinforcement of observing. Finally, the formation of a discrimination was analyzed in terms of changes in the proportion of time spent in contact with the discriminative stimuli.     

JOB ATTRIBUTES PREFERRED BY FEMALE HEALTH PROFESSIONALS, BEFORE AND AFTER ENTERING THE WORK FORCE

A longitudinal study of 125 female health professionals' preferences for 12 job characteristics was carried out at graduation and 20 months later. After employment respondents placed increased importance on skill development and respect received, and less emphasis on security and promotion opportunities. At follow-up the most valued attributes were skill development, chance to accomplish something worthwhile and friendliness of co-workers, while physical surroundings, pay and promotion were ranked as least important. Self concept measures derived from Bern's Sex Role Inventory (1974) had not changed since graduation. In both surveys, a significant association was found between masculinity and the importance attached to taking part in decisions. The results contribute to the debate concerning the intrinsic-extrinsic dichotomy in work motivation.     

Place information in multidigit number comparison

How do we use place information in a number comparison task involving multidigit numbers? In four experiments, subjects identified stimulus numbers as larger or smaller than the number 5,000 in a choice reaction time task. As the difference between the number of places in the stimulus number and the number of places in the standard decreased, response time and errors significantly increased. When the number of places was held constant, the type of numeric information extracted depended on the value of the standard (5,000 or 5,555). In some cases, irrelevant place information affected choice time.     

Premenstrual syndrom

Premenstrual syndrome is a condition with cyclical mood changes occurring in 30 % of the female population of fertile ages. The symptom development is very closely related to the luteal phase indicating the existence of one or more factors during the luteal phase that provoke mental symptoms in sensitive patients. This is further supported by the fact that hysterectomized women with no menstrual bleedings but with the ovarian hormone cycle continue to show cyclical mood changes without having the cycle phase. The nature of the symptom provocating factor is still unknown but the ovarian hormones progesterone and/or estradiol are suspected. This as certain women taking oral contraceptives and sequential postmenopausal estrogen-progestagen treatment achieve mood changes. Psychological and personality factors are probably also involved, at least in the degree of the mood change and the type of mood experienced.     

The role of noradrenaline in learned behaviors: studies using DSP4

DSP4 (N-2-chloroethyl-N-ethyl-2-bromobenzylamine) is a novel noradrenaline (NA) neurotoxin sufficiently selective, following systemic administration, to be a pharmacological tool of much potential; this possibility has warranted the extensive use of DSP4 to study the role of noradrenaline in learned behaviors. Thus, after DSP4 treatment (50 mg/kg) a very robust two-way active avoidance impairment is incurred and this deficit remained over a wide range of stimulus conditions and parameters. On the other hand, the acquisition of relatively simple tasks such as one-way active avoidance, fear conditioning, step-down passive avoidance and taste-aversion conditioning, was only slightly affected or not affected at all. DSP4 administration caused a retardation of the rate of acquisition of a "right-turn" running response for food reward in a modified T-maze, and an attenuation of the exteroceptive context effect in taste-aversion conditioning and extinction. In spite of a few similar results, NA-depletions following DSP4 generally do not produce the same behavioral effects as the 6-Hydroxydopamine lesions but are more akin to the locus coeruleus lesion. An hypothesis of the role of central NA, based mainly upon the shuttle box procedure, incorporates a function in establishing the Signal-Response association, in adapting to situations that require a correct response to stress and in maintaining an adequate span of attention to the range of environmental events presented in any given learning situation.     

The role of esteem and coping in response to a threat communication

Two experiments examined the relations among self-esteem, perceived competency to cope, and actual coping behaviors following a threat communication. Leventhal's “parallel response model” (in Advances in experimental social psychology, L. Berkowitz (Ed.), New York: Academic Press, 1970, Vol. 5) predicts that low-esteem subjects will show deficits in both competency and coping behaviors. Experiment 1 manipulated threat level of a tetanus communication. Low-esteem subjects showed coping deficits on measures of free associations, free recall, fatalism, and coping. Threat groups differed only on fear and danger measures. Experiment 2 manipulated the fear level of an antismoking film and used false feedback to alter perceived competency. Positive feedback increased perceived competency to quit smoking among low-esteem subjects only. Without feedback, low-esteem subjects reduced smoking less than high-esteem subjects; positive feedback reversed the pattern. The discussion argued that, consistent with Leventhal's model, the low-esteem coping deficit has two independent causes: (1) excessive concern with fear, and (2) inadequate perceived competency.     

Age-related changes in rate of visual information processing

Each of four groups of 12 subjects performed four psychophysical tasks. The age ranges of the four groups were 19-31, 45-57, 58-70, and 71-83 years, respectively. All four tasks required some form of visual information processing: Two were backward-masking tasks; two were temporal-integration tasks. In all four tasks increasing temporal functions over age were obtained, suggesting slower processing rates as age increased. The results support an active processing model of visual perception that interprets duration of visible persistence and duration of interval in which backward masking is effective as indices of the time course of early stages in the processing of stimulus features. The evidences also suggests that backward masking and visible persistence may be mediated by distinct mechanisms that are affected differently by aging processes. A model that conceptualizes the visual system as a multichannel processor is proposed as an explanation for some of the findings.     

Mentally retarded individuals outperform college graduates in judging the nonconservation of space and perimeter

Most adults of average and superior intelligence incorrectly assume that in a two dimensional figure two attributes, area, and perimeter, are locked in a fixed relationship such that if one remains unchanged so does the other. Consequently, when they correctly conserve one attribute during shape transformation, they incorrectly conserve the other. Mentally retarded individuals assume no such fixed relationship but depend exclusively on perceptual information. Although this dependence adversely effects their judgment of conservation, it allows them to correctly judge the changed state of the nonconserved attribute.