Effect of classical conditioning on an internal clock

Six experiments with rats used a psychophysical choice procedure to study the internal clock used to discriminate duration. They investigated if the clock is sensitive to the signal value (associative strength) of a stimulus. The experiments involved two types of trials. On choice trials, a stimulus lasted a short (e.g., 3 s) or long (e.g., 12 s) duration; then the rats chose between two levers. The rewarded choice depended on the duration of the stimulus. On conditioning trials, the stimulus used on choice trials was presented, but it ended without food (extinction trials) or with food (pairing trials) regardless of what the rat did. The main stimulus minus accuracy with the long stimulus. Experiment 1 showed that extinction trials increased short bias relative to training without conditioning trials or to training with pairing trials. The rest of the experiments tested explanations of these results. The same results were found when extinction trials were the same duration as the short stimulus (Experiment 2), when extinction trials were a random duration (Experiment 5), and when the signal value of the conditioned stimulus was changed in another way (Experiment 6). The effect of conditioning trials was modality specific (Experiments 3 and 4). Of the explanations considered, the best one--the only one not contradicted at least once--is that changing the signal value of a stimulus changes how the clock times the stimulus. Reducing signal value reduces the measured duration.     

Stuttering and the valsalva mechanism: A hypothesis in need of investigation

This note presents the hypothesis than the excessively forceful closure of the mouth of larynx associated with certain types of stuttering may involve a neurological confusion between speech and the human body's Valsalva mechanism, which is designed to increase pulmonary pressure by forceful closure of the upper airway to assist in many types of physical effort. It is suggested that such behavior may result from excessive neuromotor tuning of the Valsalva mechanism prior to speech, especially in situations where the stutterer anticipates the need to “try hard” to speak properly. Such tuning may both interfere with phonation and render the Valsalva mechanism overexcitable to triggering stimuli, such as the increase in subglottal pressure that accompanies the start of articulation.     

On the role of differential sample behaviors in matching-to-sample

Pigeons were trained on matching-to-sample (MTS) with differential sample-response requirements that were identical with respect to two pairs of sample stimuli but were either correlated or uncorrelated with correct choice. Experiment 1A showed that birds in the uncorrelated condition were slower to reach criterion levels of accuracy than birds in the correlated condition in spite of their equivalent sample discriminations. However, correlated birds were more disrupted in their matching performances than the uncorrelated birds when subsequently switched to nondifferential sample-response requirements (Experiment 1B). Experiment 2 showed that differential sample behaviors also generated higher levels of accuracy on delayed MTS when correlated with choice, and that accuracy in this condition did not differ as a function of whether the samples were hues or lines. Sample dimension did affect memory performance, on the other hand, in the uncorrelated condition. In Experiment 3, reversing differential sample-response requirements for one pair of samples substantially reduced matching accuracy in the correlated group but had almost no effect in the uncorrelated group. These findings demonstrate that differential sample behaviors directly control pigeons' matching performances and also overshadow conditional stimulus control by the samples when these behaviors are predictive of correct choice. The facilitation in matching produced by differential sample behaviors apparently arises from the additional cue these behaviors provide, not because they enhance sample discriminability.     

Early adolescent egocentrism: a review of six articles

This paper reviews six articles which appear to be representative of the past fifteen years during which researchers have focused on early adolescent egocentrism. Each article is described in chronological order and compared to research findings suggested by the other articles. Although the researchers have suggested some interesting associations, there is a lack of consistency among their findings. The author indicates methodological problems and questions for further research which arise from the reviewed articles.     

The impact of high school on social development

In reviewing the literature on the social impact of high school, six themes were identified: (1) students perceive strong norms for conformity to school rules, (2) the emphasis on conformity and control influences the quality of student/teacher relations which tend to be role bound and inflexible, (3) paths to social status continue to emphasize athletic competence, (4) peer group identification has an impact on social relations within the larger community as well as in the school setting, (5) powerlessness is felt as a result of the authoritarian approach to decision making, and (6) the overall high school environment does not enhance students' beliefs in the Bill of Rights. It was concluded that high school students have limited opportunities for flexible self-definition. As a result of the way they are treated by authority figures and the strong pressures toward conformity, many adolescents fail to learn the extent of their rights or effective strategies for the exercise of power.     

Youth suicide

The literature on youth suicide (ages 15-24) is surveyed for the period 1980-1985. Emphasis is placed on general determinants of suicide, predictors in the form of psychological tests, precipitating events (immediate causes), and signs--clues that may signify impending attempts at self-destruction. Suggestions for prevention, and limitations of research on suicide are offered.     

Keeping juvenile delinquents in school: a prediction model

The purpose of this study was to test an empirically based prediction model of school dropout on a sample of 137 juvenile delinquents, some who have dropped out and some who have remained in school. The specific factors among the many found in previous research that are salient for predicting whether delinquent youths will drop out or remain in school were determined. An important finding of this study is that it required only four factors to yield a high level of prediction: misbehavior in school, disliking school, the negative influence of peers with respect to dropping out and getting into trouble, and a marginal or weak relationship with parents. The four factors identified create a model that is directly applicable to prevention strategies and is extremely parsimonious.     

Perceptual learning of a non-focal color discrimination between ages three and six

A match-to-sample task and a preference-ranking procedure were used to provide predifferentiation experiences on a color discrimination of 3-, 4-, 5-, and 6-year-old children. Chronological age was the best predictor of task success. Six-year-olds averaged twice as many correct matches as 3-year-olds. Gender and predifferentiation experience were not significant as main effects or in interactions affecting test performance. There was no difference between scores of untrained and trained children. The predifferentiation experiences had no effect. The data suggest that the years between 3 and 6 may be an important period in the development of the perceptual abilities needed to discriminate among subtle differences in one hue. Boys' and girls' abilities seem to develop at the same rate during this age span.     

Family Characteristics and Posttraumatic Stress Disorder: A Follow-Up of Israeli Combat Stress Reaction Casualties

This study assessed the role of family status and family relationships in the course of combat-related posttraumatic stress disorder (PTSD). The sample consisted of 382 Israeli soldiers who suffered a combat stress reaction episode during the 1982 Lebanon War. Results showed that one year after the war married soldiers had higher rates of PTSD than did unmarried soldiers. Furthermore, higher rates of PTSD were associated with low expressiveness, low cohesiveness, and high conflict in the casualties' families. Theoretical, methodological, and clinical implications are discussed.     

Chronic Illness and the Life Cycle:A Conceptual Framework

This article provides a conceptual framework for thinking about the system created at the interface of chronic illness with the family life cycle. First, a psychosocial typology and time phases of illness schema is described as a necessary, preliminary step to create a common language that bridges the worlds of illness, individual, and family development. This schema organizes similarities and differences between diseases in a manner useful to psychosocial-developmental rather than biomedical inquiry. Then, drawing on several major life-cycle theories in the literature, key concepts (periods of transition, life-structure building and maintaining, centripetality, and centrifugality) are used in a complementary fashion to link these three lines of development. Equipped with these psychosocial languages, consideration is given to transgenerational aspects of illness, loss, and crisis, and the interwoven threads of illness, family, and individual development. Clinical vignettes are provided to highlight this conceptual framework.