Component probability and component reinforcer rate as biasers of free-operant detection

Six pigeons were trained on multiple schedules whose components were concurrent variable-interval extinction and concurrent extinction variable-interval schedules. In Experiments 1a and 1b the stimuli signaling the components were two different light intensities, and in Experiments 2a and 2b they were two identical intensities. The components of the multiple schedule changed probabilistically after each reinforcer. In Experiments 1a and 2a, the probability of presenting the components was varied over five conditions and a replication. In Experiments 1b and 2b, the component probability was .5 and the component reinforcer rates were varied systematically over five conditions and a replication. The data, analyzed according to the Davison-Tustin behavioral detection model, confirmed that the discriminability of the stimuli signaling the components was high when the stimuli were different, and low when the stimuli were the same. Discriminability, measured by log d, was unaffected by component probability variation and by component reinforcer-rate variation. When discriminability was high, bias, or the response allocation between the two keys, was more strongly affected by variation of reinforcer rate within components than by variation of component probability, but the reverse was found when discriminability was low. The results suggest that free-operant detection performance is controlled by the rates of reinforcers in periods of time in which stimuli signal differential contingencies. These periods comprise the components when the component stimuli are discriminable, and comprise the total session when the components are indiscriminable. An extension of the Davison-Tustin behavioral detection model that incorporates these results is presented.     

Post-training Unilateral Vagal Stimulation Enhances Retention Performance in the Rat

Many peripherally administered substances which modulate memory do not freely enter the brain. Such compounds may act through peripheral receptors that send messages centrally through vagal afferents. To explore this hypothesis, rats were chronically implanted with cuff electrodes on the left cervical vagus nerve. Each animal was trained 48 h after surgery on a one-trial inhibitory-avoidance task with a 0.75-mA, 1.0-s footshock. Immediately following training, each animal received either no stimulation or vagal stimulation (0.5-ms biphasic pulses; 20 Hz, 30 s) at one of three intensities (0.2, 0.4, 0.8 mA; eight animals per group). Retention was tested 24 h later. Neither the 0.2-in or 0.8-mA groups (22.1-s; 53.7-s median latency) showed altered retention performances, whereas the 0.4-mA group showed significantly improved retention (881.0 s) compared to unstimulated controls (21.1 s; U = 6, p < .01). This inverted-U shaped function indicates that vagal activation during memory consolidation modulates retention for memory tasks.     

Links among theory, research, and practice: cornerstones of clinical scientific progress

Discusses how explicit links among clinical theory, research, and practice are necessary if a clinical discipline is to survive in the managed care marketplace of today. Robust links among theory, research, and practice enable the elaboration of a systematic body of clinical knowledge that is practical in its deployment, effective in its methods, and compelling in its rationale. Moreover, theoretical advances are increasingly necessary, in that they allow scientists to categorize and prioritize the growing amount of empirically derived information, determine how pieces of multilevel data fit together, identify knowledge gaps, and set priorities for future studies. As shown by some of the articles in this special section, evolving theories of behavior have several characteristics in common; namely that they are developmental, transactional, contextual, adaptational, multilevel, and multidetermined. Concerns may be raised, however, as to whether current research methods are fully adequate to test these newer, more complex, multilevel theories or the clinical phenomena they seek to characterize. To address these difficulties, as well as to increase the pace of scientific advances that may result from propitious links among theory, research, and practice, I offer several recommendations to clinical psychology in general and to clinical child psychological research in particular.     

Informant-Based Determinants of Symptom Attenuation in Structured Child Psychiatric Interviews

Informant-related determinants of item attenuation, that is, the drop-off in symptom endorsement rates at retest, were examined in an enriched community subsample of 245 parent–child pairs drawn from the National Institute of Mental Health Methods for Epidemiology of Child and Adolescent Mental Disorders Study. Youngsters and their parents were interviewed with the Diagnostic Interview Schedule for Children (Version 2.3; DISC-2.3) on two occasions with a mean test–retest interval of 12 days. Item attenuation rates were high for both informants, with adults failing to confirm 42% and children 58% of baseline responses at retest. Stepwise regressions revealed that item attenuation at DISC-P retest was higher for adult informants who were younger, and who reported on older and less impaired children. On the DISC-C, attenuation was higher for children who were less impaired, rated as doing worse in school, and who had a longer test–retest interval. These results are broadly consistent with past studies examining the determinants of attenuation and test–retest reliability and have implications for the design and use of structured diagnostic instruments.     

DEVELOPMENT OF BASIC AUDITORY DISCRIMINATION IN PRESCHOOL CHILDREN

Abstract— Intensity (loudness), frequency (pitch), and duration discrimination were examined in 41 normal-hearing children, aged 4 to 6 years, and 9 adults. A second study retested 25 of the youngest children 12 to 18 months later. Intensity discrimination showed the least improvement with age and was adultlike by age 5 for most of the children. In contrast, frequency and duration discrimination showed highly significant improvement with age, but remained poorer than adults' discrimination for many 6-year-olds. Large individual differences were observed within alt tasks and age groups.     

The effects of three abstinence sex education programs on student attitudes toward sexual activity

The effects of three abstinence sex education programs on student attitudes toward sexual activity were studied. The programs were administered to 7th- and 10th-grade students in three school districts in the State of Utah. All students were administered a pre- and posttest survey to determine attitude change. The independent variables were program, grade level, gender, and pre/posttest. The dependent variable was the combined and averaged response to 12 questions taken from the survey. There was a four-way interaction between the independent variables. The Sex Respect program produced the most positive attitude change.     

Depressive symptom patterns among older women

The structure of depressive symptom patterns was investigated in a community sample of 344 women between the ages of 51 and 92 who were administered the SCL-90-R Depression and Additional Symptoms Scales. Confirmatory factor analysis was used to test alternative measurement hypotheses implied by clinical formulations of depressive symptom patterns among elderly persons. The findings show support for the hypothesis that 2 somewhat different depressive syndromes, along with 4 more delimited forms of distress, underlie symptom-reporting patterns. Implications of these findings for future research on the relation between aging and depression are discussed.     

The effect of specific hypnotic suggestions on blood pressure in normotensive subjects

Twenty normotensive subjects participated on a voluntary basis in an experiment designed to study the effects of specific suggestions on blood pressure (BP). After an induction procedure, the experimental group received suggestions presumed to be relatively nonactivating, although capable of lowering or raising BP. A control group was used to record the BP changes over time. All subjects met for one session. Eight subjects from the experimental group met for a second session. Both adaptation and induction resulted in significant BP decreases. A specific suggestion to increase BP gave a significant result when compared to the induction point. There was no significant change from induction to the BP decrease suggestion. Both systolic and diastolic BP behaved in the same way. A second experimental session resulted in no significant change compared with the first session. Also, no significant difference was found in suggestibility scores from the first to the second session. The results are in line with previously published studies.