Effects of D-amphetamine and ethanol on variable and repetitive key-peck sequences in pigeons

This experiment assessed the effects of d-amphetamine and ethanol on reinforced variable and repetitive key-peck sequences in pigeons. Pigeons responded on two keys under a multiple schedule of Repeat and Vary components. In the Repeat component, completion of a target sequence of right, right, left, left resulted in food. In the Vary component, 4-peck sequences differing from the previous 10 produced food. d-Amphetamine (0.1-3.0 mg/kg, i.m.) was administered in two separate phases, separated by ethanol administration (1.0-2.0 g/kg, i.g.). Under control conditions, measures of variability were high in the Vary component, and lower in the Repeat component. Following administration of the highest dose of d-amphetamine, but not ethanol, response rates decreased in both components. d-Amphetamine and ethanol tended to increase overall sequence variability in the Repeat component, and had less of an effect in the Vary component. Performance in the Repeat component during Phase 2 of d-amphetamine administration was more disrupted than during Phase 1. Measures of variability and repetition based on shifts in the relative frequency distributions of the 16 possible keypeck sequences differed from those based on the overall measure of variability, highlighting the importance of considering both molar and molecular measures when assessing the effects of drugs on reinforced variability and repetition. In addition, the shifts in the relative frequency distribution of response sequences suggest that d-amphetamine produced decrements in repeat performance by decreasing discriminative control within response sequences, whereas ethanol decreased repeat performance by decreasing discriminability between components as well as discriminative control within response sequences.     

Memory and interpretation of visual representations of threat in socially anxious and nonanxious individuals

The present study was designed to replicate and extend results reported by Brendle and Wenzel (Behav. Res. Ther. 42 (2004) 155), who found that socially anxious individuals accurately recalled threat-relevant information but subsequently imposed a biased interpretation upon that same material, using more ecologically valid stimuli. Socially anxious (n=37) and nonanxious (n=47) individuals viewed two positive, two negative, and two neutral video vignettes and completed two cognitive tasks assessing memory and interpretation of factual details immediately and after 48 h. Similar to the results reported by Brendle and Wenzel (2004), socially anxious and nonanxious individuals did not differ in their memory for details that had been presented in the vignettes. However, socially anxious individuals made more negative interpretations of details included in the vignettes than nonanxious individuals, although unlike Brendle and Wenzel (2004), they did not demonstrate the tendency to make less positive interpretations. It is concluded that socially anxious individuals are characterized by interpretation biases when presented with threat-relevant information, and there is no evidence to suggest that they are characterized by memory biases for threat-relevant information.     

The effects of methylphenidate on a functional analysis of disruptive behavior: a replication and extension

In the present investigation, a functional analysis of the disruptive behavior of a 18-year-old man who had been diagnosed with attention deficit hyperactivity disorder and moderate mental retardation was conducted, both when he was taking methylphenidate and when he was not taking the medication. The results of this functional analysis demonstrated that the participant's disruptive behaviors were reinforced by access to attention only when he was not taking methylphenidate.     

Prayers, spiritual support, and positive attitudes in coping with the September 11 national crisis

This study was designed to help fill gaps in faith-related and positive psychology research. Psychologists have called for precise assessment of effective faith factors inherent within spiritual experiences that may explain their beneficial effects. Positive psychologists suggest the need to examine social and faith-related origins of optimism. Based on previous research, we redefined spiritual support and developed a new assessment. The study is a survey of 453 graduate and undergraduate students 3 months after the September 11, 2001, terrorist attacks. The results showed that participants, who believed in diverse spiritual entities, used various types of prayer for coping. A structural equation model showed that a linkage of spiritual support and positive attitudes mediated the effect of faith-based and secular factors on post-September 11 distress. Higher levels of initial negative emotional response were associated with the use of prayer for coping, which was, in turn, related to less distress through the pathway of the above linkage.     

When opposites attract: a multi-sample demonstration of complementary person-team fit on extraversion

This study assessed the nature of the person-team fit relationships for extraversion on members' attraction toward their teams. Unlike most studies of personality-based fit, which emphasize similarity, we predicted that complementary fit on extraversion (i.e., high individual-low team or low individual-high team levels) would result in greater attraction to the team. Data from two independent samples of intact project teams were analyzed, including 324 MBA students comprising 64 case analysis teams and 217 members of 26 manufacturing teams. Using polynomial regression analysis and three-dimensional surface plots, our results supported the predicted relationship. In addition, the data indicated that individuals who were more attracted to their teams were also better performers, as judged by their peers and supervisors.     

Effects of reinforcement schedule on facilitation of operant extinction by chlordiazepoxide

Learning and memory are central topics in behavioral neuroscience, and inbred mice strains are widely investigated. However, operant conditioning techniques are not as extensively used in this field as they should be, given the effectiveness of the methodology of the experimental analysis of behavior. In the present study, male C57B1/6 mice, widely used as background for transgenic studies, were trained to lever press on discrete-trial fixed-ratio 5 or fixed-interval (11 s or 31 s) schedules of food reinforcement and then exposed to 15 extinction sessions following vehicle or chlordiazepoxide injections (15 mg/kg i.p., administered either prior to all extinction sessions, or prior to the final 10 extinction sessions). Extinction of operant behavior was facilitated by drug administration following training on either schedule, but this facilitation only occurred once a number of extinction sessions had taken place. The extinction process proceeded more rapidly following fixed-interval training. Resistance to extinction was equally high following training with either schedule type, and was reduced by drug administration in both cases. These phenomena were evident in individual cumulative records and in analyses of group data. Results are interpreted in terms of phenomena of operant extinction identified in Skinner's (1938) Behavior of Organisms, and by behavioral momentum theory. These procedures could be used to extend the contribution of operant conditioning to contemporary behavioral neuroscience.     

EFFECTS OF MORPHINE ON TEMPORAL DISCRIMINATION AND COLOR MATCHING: GENERAL DISRUPTION OF STIMULUS CONTROL OR SELECTIVE EFFECTS ON TIMING?

Discrepant effects of drugs on behavior maintained by temporal-discrimination procedures make conclusive statements about the neuropharmacological bases of timing difficult. The current experiment examined the possible contribution of a general, drug-induced disruption of stimulus control. Four pigeons responded on a three-component multiple schedule that included a fixed-interval 2-min, temporal discrimination, and color-matching component. Under control conditions, response rates and choice responses during the first two components showed evidence of control by time, and accuracy for color matching was high in the third component. Morphine administration flattened the distribution of fixed-interval responding and produced a general disruption of accuracy in the temporal-discrimination component, whereas accuracy in the color-matching component was relatively unaffected. Analysis of the psychophysical functions from the temporal-discrimination component indicated that morphine decreased accuracy of temporal discrimination by decreasing overall stimulus control, rather than by selectively affecting timing. These results suggest the importance of determining the neurophysiological bases of stimulus control as it relates to temporal discrimination.     

Self-engagement, stressors, and health: a longitudinal study

The authors examined whether engagement in a performance domain could buffer or exacerbate the consequences of different stressors. Soldiers completed measures of engagement in work, work demands (days training, work hours, and subjective work overload), and symptoms at two time periods. Engagement in work interacted with days training and work hours at Time 1 to predict health symptoms at Time 2 (after controlling Time 1 outcomes). Soldiers highly engaged in their jobs were less likely to report negative consequences under high levels of training/work hours in comparison to soldiers disengaged from their jobs. However, engagement in work interacted with work overload in the opposite manner, with high levels of engagement potentiating the relationship between overload and reports of health symptoms. Engagement in a domain appears to buffer individuals from stressors that do not undermine performance but may exacerbate the impact of stressors that compromise performing well in the domain.     

Cognition at risk: Gestalt/feature-intensive processing,attention deficit,and substance abuse

Attention deficit hyperactive disorder (ADHD) is associated with elevated levels of substance abuse, but the cognitive linkages involved have been little explored. The present study builds upon earlier work showing that more gestalt, as opposed to feature-intensive, styles of processing are conductive to substance abuse, especially in those with ADHD symptoms. The work reported here indicates that a protective factor against substance abuse may lie in relatively efficient heuristic processing, especially synthetic or inferential heuristic processing, but further demonstrates that those with ADHD symptoms tend to have poorer abilities in this regard, even at the subclinical, nondiagnosed level. Results are discussed in terms of the gestalt/featureintensive processing theory of cognition.     

A simplified technique for scoring DSM-IV personality disorders with the Five-Factor Model

The current study compares the use of two alternative methodologies for using the Five-Factor Model (FFM) to assess personality disorders (PDs). Across two clinical samples, a technique using the simple sum of selected FFM facets is compared with a previously used prototype matching technique. The results demonstrate that the more easily calculated counts perform as well as the similarity scores that are generated by the prototype matching technique. Optimal diagnostic thresholds for the FFM PD counts are computed for identifying patients who meet diagnostic criteria for a specific PD. These threshold scores demonstrate good sensitivity in receiver operating characteristics analyses, suggesting their usefulness for screening purposes. Given the ease of this scoring procedure, the FFM count technique has obvious clinical utility.