Stochastic PERT networks as models of cognition: Derivation of the mean,variance, and distribution of reaction time using Order-of-Processing (OP) diagrams

It is frequently assumed that the mental activity which leads to a given response is made up of separable components or processes. One or more of the processes are assumed to contribute to the time required to respond. Computation of the mean, variance, and distribution of the reaction time is relatively straightforward when all processes are arranged in series or parallel. However, such is not the case when the processes have complex arrangements. A solution to a useful special case of the above problem is proposed. Specifically, it is shown that simple computations yield closed form expressions for the mean, variance, and distribution of reaction time when the processes can be arranged in a stochastic PERT network and when the durations of individual processes are sums of mutually independent, exponentially distributed random variables. The method of solution relies on the construction of an Order-of-Processing (OP) diagram from the original PERT network representation of behavior.     

The organization of spontaneous leg movements in newborn infants

Spontaneous, supine kicking in newborn (2- and 4-week-old) infants is described in terms of its temporal structure, interjoint coordination, and muscle activation characteristics as measured by surface electromyography. Phasic kick movements shoed a constrained temporal organization in the movement, but not the pause phases. Hip, knee, and ankle joints moved in temporal and spatial synchrony, and all three joints showed a rhythmical or periodic organization over time. EMGs revealed antagonist coactivation at the initiation of the flexor movement, but little or not extensor activity. The dorsal muscles, the gastrocnemius and hamstrings, showed less activity than the ventral pair, tibialis anterior and quadriceps. Burst and onset-to-peak durations were also constrained. As a result of neural mechanisms and biomechanical forces, newborn leg movements are structured muscle synergies. This organization has implications both for newborn functioning and for later development.     

Situational and Arousal-Based Messages and the Reduction of Crowding Stress

In an anticipatory crowding context, an attempt was made to assess the effects of various control-relevant messages for ameliorating crowding stress. Two informational foci (i.e., situational and emotional) were employed, and it was found that situational information was more effective in relieving discomfort associated with anticipated high-density than emotionally-focused information. In addition, an exploratory attempt was made to evaluate the effectiveness for relieving crowding stress of control-relevant information highlighting different aspects of density (i.e., overload, spatial intrusion, and interference). In general, it was found that such messages were effective in relieving discomfort to the extent that they accurately described the characteristics of the setting that subjects were anticipating.     

Counselling, support and advice: The adolescent viewpoint

Few discussions on counselling pay more than lip service to what adolescents actually want. Data presented on the preferences of adolescents with regard to helping services show that no one method of providing help would be adequate. An indication of the number of relatively Isolated and unsupported adolescents is given, suggesting that 20-40% of young people lack a regular source of advice or understanding. Professional and official sources of advice are rarely used, and are not likely to be until they improve both their accessibility and image in the eyes of youth.     

Individual Differences in Affective,Evaluative, and Behavioral Responses to an Erotic Film1

The current research sought to replicate and explore further unexpected pilot data indicating that negative reactions to filmed erotica may be associated with post-exposure increases in sexual activity. Subjects (31 males, 31 females) viewed an erotic film; background variables, affective, evaluative, and sexual-behavioral responses were assessed. Compared to individuals who evaluated the film as relatively nonpornographic, those who rated it as pornographic reported more restrictive sexual socialization experiences and more negative attitudes towards sex, responded to the film with more negative affect, and showed greater increases in sexual activity subsequent to exposure (all p <.05). Additional analyses provided some evidence that evaluations mediated behavioral responses to the stimulus. Cognitive labeling, transfer of arousal, and disinhibition considerations which may account for the relationship between responses to erotica and post-exposure sexual activity were discussed.     

Anxiety and sex role in body landmark functions

Two hypotheses were evaluated. One proposed that the more prominent a body landmark the less anxiety will be evoked by a theme linked to that landmark. The relation was determined between landmark prominence and anxiety evoked by a taped message appropriate to the landmark-linked theme. Two female samples were studied. The findings supported the hypothesis. A second hypothesis proposed that enhancing awareness of body landmarks under threat conditions is positively related to degree of masculinity and negatively related to degree of femininity. Changes in landmark awareness during appropriate taped messages were studied in two male and two female samples. Masculinity-femininity was also measured. The findings were particularly supportive of the hypothesis relating masculinity to mobilization of landmarks.     

Competitiveness in males and in females

Male and female undergraduates performed a task at which they either succeeded or failed in competition with either a male or female partner who subsequently either accepted or rejected them. Subjects who were rejected by a male partner following success or accepted following failure performed less well on a subsequent anagram task than did those who were accepted following success or rejected following failure. These results suggest the importance of situational factors as determinants of fear of success behavior.