Human performance on negative slope schedules of points exchangeable for money: a failure of molar maximization

Panel pressing was generated and maintained in 5 adult humans by schedules of points exchangeable for money. Following exposure to a variable-interval 30-s schedule and to a linear variable-interval 30-s schedule (which permitted points to accumulate in an unseen "store" in the absence of responding), subjects were exposed to a series of conditions with a point-subtraction contingency arranged conjointly with the linear variable-interval schedule. Specifically, points were added to the store according to the linear-variable interval 30-s schedule and were subtracted from the store according to a ratio schedule. Ratio value varied across conditions and was determined individually for each subject such that the subtraction contingency would result in an approximately 50% reduction in the rate of point delivery. Conditions that included the subtraction contingency were termed negative slope schedules because the feedback functions were negatively sloped across all response rates greater than the inverse of the variable-interval schedule, in this case, two per minute. Overall response rates varied inversely with the subtraction ratio, indicating sensitivity to the negative slope conditions, but were in excess of that required by accounts based on strict maximization of overall reinforcement rate. Performance was also not well described by a matching-based account. Detailed analyses of response patterning revealed a consistent two-state pattern in which bursts of high-rate responding alternated with periods of prolonged pausing, perhaps reflecting the joint influence of local and overall reinforcement rates.     

Cognitive processes underlying coping flexibility: differentiation and integration

This study investigates how individuals formulate flexible coping strategies across situations by proposing differentiation and integration as two stress-appraisal processes. Results showed that participants who coped more flexibly adopted the dimensions of controllability and impact in differentiating among different stressful situations. They also deployed an integrated strategy: the deployment of more monitoring in situations perceived as controllable but less of this strategy in situations perceived as uncontrollable. Participants who coped less flexibly did not adopt any given dimensions and tended to use more monitoring regardless of situational characteristics. These results suggest that individuals with different extents of coping flexibility differ in the cognitive processes. Individuals who cope more flexibly display a greater extent of differentiation and integration than do those who cope less flexibly. These findings are translated into strategies for stress management workshops.     

Validation of the psychopathic personality inventory on a female inmate sample

This investigation evaluated the construct validity of the Psychopathic Personality Inventory (PPI; Lilienfeld & Andrews, 1996), a self-report measure designed to assess psychopathy. One hundred and two incarcerated females were administered the Kaufman Brief Intelligence Test (K-BIT), an oral alcohol and drug screening measure, a demographic interview, the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), the Psychopathy Checklist-Revised (PCL-R), and the PPI. There were significant correlations among the PPI, MMPI-2 scales, and the PCL-R. In addition, the correlations between the PPI and the separate PCL-R factors were not significantly different from each other, indicating that the PPI is assessing both facets of the psychopathy construct to some extent. A high correlation between the PPI and the DSM-IV criteria, which assesses adult antisocial behaviors, revealed adequate concurrent validity. Nonsignificant or negligible correlations between the PPI and the MMPI-2 scales provided some support for discriminant validity. The results are discussed with respect to the clinical and forensic utility of the PPI, the limitations of the study, and the need for further research.     

The sectored foraging field: a novel design to quantify spatial strategies, learning, memory, and emotion

Although Norway rats are naturally gregarious, males typically live alone at some point during adulthood. Different social ecologies often require different learning strategies and also modulate response to stressors and gonadal development. To measure effects of the social environment on the interaction between cognition and emotion during aging, we focused on a natural learning context and devised the sectored foraging field, a progressively difficult spatial navigation task. Here, we describe how this apparatus and protocol permits multiple learning strategies in a minimally stressful environment, enabling finely graded analyses of cognition and emotionality. Male Sprague-Dawley rats living alone throughout adulthood adopted a sex-typic discernible spatial strategy. In contrast, males housed in group contexts utilized an algorithmic kinesthetic strategy, repeating the same motor action until they found food. Removal of food and distal, but not local cues, elicited anxious alertness, particularly in group-housed males. Cognitive performance of group-housed rats subsequent to food and cue removal was significantly impaired, yet enhanced in isolates.     

Treatment of panic disorder: live therapy vs. self-help via the Internet

A randomized trial was conducted comparing 10 individual weekly sessions of cognitive behaviour therapy for panic disorder (PD) with or without agoraphobia with a 10-module self-help program on the Internet. After confirming the PD diagnosis with an in-person structured clinical interview (SCID) 49 participants were randomized. Overall, the results suggest that Internet-administered self-help plus minimal therapist contact via e-mail can be equally effective as traditional individual cognitive behaviour therapy. Composite within-group effect sizes were high in both groups, while the between-group effect size was small (Cohen's d=16). One-year follow-up confirmed the results, with a within-group effect size of Cohen's d=0.80 for the Internet group and d=0.93 for the live group. The results from this study generally provide evidence to support the continued use and development of Internet-distributed self-help programs.     

Disclosure of HIV-Positive Status to Latino Gay Men's Social Networks

This study explored disclosure of serostatus in a sample of 155 HIV-positive Latino gay men from New York City and Washington, DC. We examined rates of disclosure to different members of the social network: mothers, fathers, close friends, and primary sexual partners. There were high rates of disclosure of HIV-positive serostatus to main partners and closest friends and lower rates to fathers and mothers. We examined the role of 3 contextual target-dependent factors (emotional closeness to target, anticipated reactions from target, and target's knowledge of sexual orientation), as well as acculturation and time since diagnosis. Three separate logistic regression models were performed to predict disclosure of HIV-positive status to 3 targets: mothers, fathers, and closest friends. We found that disclosure was not a generalized tendency, but rather different factors were influential depending on the target. Whether the target was aware of participant's sexual orientation was associated with disclosure in all 3 models. Greater emotional closeness also predicted disclosure to mother and father; greater U.S. acculturation was associated with disclosure to father and marginally to mother. A longer time since diagnosis was associated with disclosure to the closest friend. These findings highlight the importance of taking into account roles and relationships, and their effect on disclosure.     

Apraxia differs in corticobasal degeneration and left-parietal stroke: A case study.

Corticobasal degeneration (CBD) is a progressive disorder characterized by both cortical and basal ganglia dysfunction such as asymmetrical apraxia, and akinetic rigidity, involuntary movements, and cortical sensory loss. Although apraxia is a key finding for the differential diagnosis of CBD, it has not been determined whether the features of apraxia seen in subjects with CBD are similar to those features exhibited by subjects with left-hemisphere damage from stroke. Therefore, for both clinical purposes and in order to better understand the brain mechanisms that lead to apraxia in CBD, we studied praxis in a patient with CBD and compared him to patients who are apraxic from left-parietal strokes. We used three-dimensional movement analyses to compare the features of apraxic movement. This subject with CBD was a dentist whose initial complaint had been that he "forgot" how to use his tools in the mouths of his patients. Analyses were performed on the trajectories made when using a knife to actually slice bread, and when repetitively gesturing slicing made to verbal command. Movements of the left hand, wrist, elbow, and shoulder were digitized in 3-D space. Although the CBD subject was clearly apraxic, the features of his apraxia differed markedly from those of the subjects with lesions in the left parietal lobe. For movements to command, the CBD subject showed joint coordination deficits, but his wrist trajectories were produced in the appropriate spatial plane, were correctly restricted to a single plane, and, like control subjects, were linear in path shape. However, when he was actually manipulating the tool and object, all of these aspects of his trajectories became impaired. In contrast, the deficits of the apraxic subjects with left-parietal damage were most pronounced to verbal command with their movements improving slightly although remaining impaired during actual tool and object manipulation. Unlike patients with parietal strokes, patients with CBD have degeneration in several systems and perhaps deficits in these other areas may account for the differences in praxic behavior.     

Definitions of physical abuse: A preliminary inquiry into children's perceptions

Research and policy-makers have frequently called for operational definitions of child abuse, however neither group has considered including children's perceptions of what constitutes abuse. The purpose of this study was to expand the discussion on definitions of child abuse by examining children's perceptions of physical abuse. This was done by collecting data to begin to document abused children's ratings of the seriousness of various abusive acts and to begin to examine gender and age differences in children's perceptions. The data revealed significant differences in children's perceptions of the seriousness of specific acts of abuse and a significant interaction between age and type of abuse. Although young children generally produced lower seriousness ratings than older children, their ratings were significantly lower on only a few types of abuse. When children's ratings were compared to similar ratings reported in earlier studies of adolescents, community members, and mental health professionals, the children in this study rated the abusive acts as less serious than the adolescents or community members, but very similar to the professionals who work in the area of child abuse and neglect. Although this must be considered a preliminary investigation, the potential implications for various legal and social contexts are discussed.