Effects of reinforcement history on response rate and response pattern in periodic reinforcement

Several researchers have suggested that conditioning history may have long-term effects on fixed-interval performances of rats. To test this idea and to identify possible factors involved in temporal control development, groups of rats initially were exposed to different reinforcement schedules: continuous, fixed-time, and random-interval. Afterwards, half of the rats in each group were studied on a fixed-interval 30-s schedule of reinforcement and the other half on a fixed-interval 90-s schedule of reinforcement. No evidence of long-term effects attributable to conditioning history on either response output or response patterning was found; history effects were transitory. Different tendencies in trajectory across sessions were observed for measures of early and late responding within the interreinforcer interval, suggesting that temporal control is the result of two separate processes: one involved in response output and the other in time allocation of responding and not responding.     

Prefrontal brain activity predicts temporally extended decision-making behavior

Although functional neuroimaging studies of human decision-making processes are increasingly common, most of the research in this area has relied on passive tasks that generate little individual variability. Relatively little attention has been paid to the ability of brain activity to predict overt behavior. Using functional magnetic resonance imaging (fMRI), we investigated the neural mechanisms underlying behavior during a dynamic decision task that required subjects to select smaller, short-term monetary payoffs in order to receive larger, long-term gains. The number of trials over which the longterm gains accrued was manipulated experimentally (2 versus 12). Event-related neural activity in right lateral prefrontal cortex, a region associated with high-level cognitive processing, selectively predicted choice behavior in both conditions, whereas insular cortex responded to fluctuations in amount of reward but did not predict choice behavior. These results demonstrate the utility of a functional neuroimaging approach in behavioral psychology, showing that (a) highly circumscribed brain regions are capable of predicting complex choice behavior, and (b) fMRI has the ability to dissociate the contributions of different neural mechanisms to particular behavioral tasks.     

Teaching business ethics to professional engineers

Without question “business ethics” is one of the hot topics of the day. Over the past months we have seen business after business charged with improper practices that violate commonly-accepted ethical norms. This has led to a loss of confidence in corporate management, and has had severe economic consequences. From many quarters business educators have heard the call to put more emphasis on ethical practices in their business courses and curricula. Engineering educators are also heeding this call, since the practice of engineering usually involves working for (or leading) a business and/or engaging in business transactions. In the summer of 2002, Auburn University’s Engineering Professional Development program made the decision to produce—based on the author’s Executive MBA course in Business Ethics—a distance-delivered continuing education program for professional engineers and surveyors. Participants across the USA now may use the course to satisfy continuing education requirements with respect to professional licensing and certification. This paper outlines the purpose and content of the course and describes its production, distribution, application, and evaluation. An earlier version of this paper was presented at the “Ethics and Social Responsibility in Engineering and Technology” meeting, New Orleans, 2003.     

The necessity and the value of placebo

The use of placebo in clinical trials has been repeatedly challenged as being unacceptable from an ethical point of view. The present paper responds to this criticism by taking up the issue in the light of the pertinent provisions of the Helsinki Declaration. Examples from different therapeutic areas are given that highlight the importance of placebo in situations in which its use is acceptable according to the Declaration. Particular emphasis is given to the question of active control trials, which, under conditions of low assay sensitivity, may become an ethically less acceptable approach than the use of a placebo control. An earlier version of this paper was presented at an international conference, “Placebo: Its Action and Place in Health Research Today,” held in Warsaw, Poland on 12–13 April, 2003.     

Psychopathy is related to negative affectivity but not to anxiety sensitivity

Although the hypothesis that psychopathic individuals are characterized by a reduced capacity for experiencing anxiety is central to many theories of psychopathy, most prior studies have examined anxiety and fear measures generally considered outdated in the literature. Moreover, prior findings are mixed, with several studies reporting no relationships between psychopathy and anxiety, and others suggesting negative relationships for the affective, interpersonal aspects of the disorder and positive relationships for the antisocial behavior dimension. To examine whether psychopathy dimensions are associated with contemporary measures of anxiety, the Anxiety Sensitivity Index and State Trait Anxiety Inventory-Trait scale were administered to 157 male inmates. Participants also completed the MMPI-derived Welsh Anxiety Scale (WAS), commonly used in psychopathy studies. Analyses provide no evidence for a negative relationship between psychopathy's affective, interpersonal factor and anxiety sensitivity after controlling for trait anxiety. Trait anxiety and WAS scores were positively associated with the antisocial behavior dimension of psychopathy. Findings do replicate prior relationships between the WAS and psychopathy, suggesting the WAS may measure aspects of negative affectivity that differ from anxiety.     

The factor structure of the Anxiety Sensitivity Index among Northern Plains Native Americans

Within our current research climate, an emphasis has been placed on examining the cross-cultural applicability of psychological tools, and exploring their utility with people of different backgrounds. Within this line of investigation lies the risk of classifying people too broadly and masking important regional, tribal, or dialectical differences. This may be particularly potent among Native Americans, given the number of distinct indigenous entities. This study examined the psychometric characteristics of the Anxiety Sensitivity Index with a tribally homogeneous sample, as compared to previous tribally-heterogeneous and majority culture findings. Results suggested that data from a homogeneous Native American sample poorly fit factor solutions reported from heterogeneous Native American and Caucasian samples, and favored a unifactorial solution. Implications for assessment with Native American peoples are discussed.     

The Suspended Aesthetic: Slavoj Žižek on Eastern European Film

Slavoj iek's writings on Krzysztof Kies´lowski and Andrej Tarkovskij represent direct challenges to the Central and Eastern European tradition of spiritual art and to dominant aesthetic concepts as such. He refuses to separate the solemn films of Kies´lowski and Tarkovskij from popular culture and stresses their import as ethical statements by their directors. Despite this ethical emphasis, iek makes an important contribution to philosophical aesthetics. He implicitly defines art as a suspension of reality which reveals time in its fragility and potentiality. Defining iek's aesthetics in terms of suspension helps to explain his partiality for Kies´lowski and Tarkovskij and bears comparison to the Russian tradition of philosophical aesthetics, in particular Aleksej Losev and Alexander Bakshy.     

The relationship between disgust sensitivity, anxiety and obsessions

Three hundred participants, including volunteers from an obsessional support group, filled in questionnaires relating to disgust sensitivity, health anxiety, anxiety, fear of death, fear of contamination and obsessionality as part of an investigation into the involvement of disgust sensitivity in types of obsessions. Overall, the data supported the hypothesis that a relationship does exist between disgust sensitivity and the targeted variables. A significant predictive relationship was found between disgust sensitivity and total scores on the obsessive compulsive inventory (OCI; Psychological Assessment 10 (1998) 206) for both frequency and distress of symptomatology. Disgust sensitivity scores were significantly related to health anxiety scores and general anxiety scores and to all the obsessional subscales, with the exception of hoarding. Additionally, multiple regression analyses revealed that disgust sensitivity may be more specifically related to washing compulsions: frequency of washing behaviour was best predicted by disgust sensitivity scores. Washing distress scores were best predicted by health anxiety scores, though disgust sensitivity entered in the second model. It is suggested that further research on the relationship between disgust sensitivity and obsessionality could be helpful in refining the theoretical understanding of obsessions.     

Pain anxiety among chronic pain patients: specific phobia or manifestation of anxiety sensitivity?

Rather than viewing anxiety among chronic pain patients as simply a component of negative affectivity, investigators have developed a model of "pain anxiety" in which patients develop fear and avoidance of activity linked to pain. We examined whether pain anxiety can be conceptualized as a specific phobia, or whether evidence supported the notion that pain anxiety is better understood as a manifestation of anxiety sensitivity in the context of chronic pain. Chronic musculoskeletal pain patients (N=70) underwent cold pressor and mental arithmetic tasks while cardiovascular, self-report, and behavior indexes were recorded. They completed measures of pain anxiety, anxiety sensitivity, fear of negative evaluation, depression and trait anxiety. Correlation analyses showed pain anxiety was related to pain-relevant responses during cold pressor, but it was also related to evaluation-relevant responses during cold pressor, and to pain- and evaluation-relevant responses (including subtraction accuracy) during mental arithmetic. Regression analyses showed that almost all effects of pain anxiety on task responses were accounted for by anxiety sensitivity. Fear of negative evaluation, in contrast, correlated only with evaluation-relevant responses, and mostly during mental arithmetic. These effects remained significant when depression, trait anxiety, or anxiety sensitivity were statistically controlled. Pain anxiety may be an expression of anxiety sensitivity rather than a circumscribed phobia; a distinction that could profitably guide treatment strategies.     

Model comparison of nonlinear structural equation models with fixed covariates

Recently, it has been recognized that the commonly used linear structural equation model is inadequate to deal with some complicated substantive theory. A new nonlinear structural equation model with fixed covariates is proposed in this article. A procedure, which utilizes the powerful path sampling for computing the Bayes factor, is developed for model comparison. In the implementation, the required random observations are simulated via a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. It is shown that the proposed procedure is efficient and flexible; and it produces Bayesian estimates of the parameters, latent variables, and their highest posterior density intervals as by-products. Empirical performances of the proposed procedure such as sensitivity to prior inputs are illustrated by a simulation study and a real example.This research is fully supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (Project No. CUHK 4346/01H). The authors are thankful to the Editor, the Associate Editor, and anonymous reviewers for valuable comments which improve the paper significantly, and grateful to ICPSR and the relevant funding agency for allowing use of the data in the example. The assistance of Michael K.H. Leung and Esther L.S. Tam is gratefully acknowledged.