Relationship between religion-related factors and obsessive compulsive disorder

This exploratory study sought to determine whether selected religion-related factors differentiated between 86 patients with obsessive compulsive disorder (OCD), 73 patients with panic disorder, and 292 patients with other psychiatric (non-anxiety) disorders. A standard history questionnaire was used to obtain information from patients concerning religion of origin, involvement in religious activities, religious conflict, and perceived religiousness of parents. It was found that the percentage of patients who reported experiencing religious conflict was significantly higher for the OCD group than for the other two groups. Other findings suggested associations between Catholicism and OCD and between Protestantism and panic disorder, but further research is needed to clarify these relationships. This article is based on a paper presented at the 98th annual convention of the American Psychological Association, Boston, August 1990.     

Suicide attempts in twins whose co-twins' deaths were non-suicides

Familial similarity for suicidal behavior has been interpreted by psychosocially oriented researchers as reflecting extreme grief following loss. This view would anticipate a higher frequency of attempted suicide among bereaved MZ than DZ twins (regardless of cause of death), given their generally increased social closeness. Alternatively, support for a genetic influence on suicidal behavior has been provided by findings of greater concordance among monozygotic (MZ) than dizygotic (DZ) twins, and among biological than adoptive relatives. This approach predicts that the occurrence of suicidal attempts among bereaved MZ and DZ twins whose co-twins deaths were non-suicides should not differ and should be low in frequency, given an absence of predisposing genetic factors. Attempted suicide was compared in 166 MZ and 79 DZ twins whose co-twins' deaths were non-suicides. Suicidal attempts (during the first two months following the loss) were recalled by 3 MZ twins (1.8%) and by 3 DZ twins (3.7%), a difference that was not significant. The present study, together with previous twin and adoption studies, supports the view that concordance for suicide among family members reflects a common genetic predisposition to suicidal behavior.     

Goal-directed decision making as probabilistic inference: a computational framework and potential neural correlates

Recent work has given rise to the view that reward-based decision making is governed by two key controllers: a habit system, which stores stimulus-response associations shaped by past reward, and a goal-oriented system that selects actions based on their anticipated outcomes. The current literature provides a rich body of computational theory addressing habit formation, centering on temporal-difference learning mechanisms. Less progress has been made toward formalizing the processes involved in goal-directed decision making. We draw on recent work in cognitive neuroscience, animal conditioning, cognitive and developmental psychology, and machine learning to outline a new theory of goal-directed decision making. Our basic proposal is that the brain, within an identifiable network of cortical and subcortical structures, implements a probabilistic generative model of reward, and that goal-directed decision making is effected through Bayesian inversion of this model. We present a set of simulations implementing the account, which address benchmark behavioral and neuroscientific findings, and give rise to a set of testable predictions. We also discuss the relationship between the proposed framework and other models of decision making, including recent models of perceptual choice, to which our theory bears a direct connection.     

Extending the simultaneous-sequential paradigm to measure perceptual capacity for features and words

In perception, divided attention refers to conditions in which multiple stimuli are relevant to an observer. To measure the effect of divided attention in terms of perceptual capacity, we introduce an extension of the simultaneous-sequential paradigm. The extension makes predictions for fixed-capacity models as well as for unlimited-capacity models. We apply this paradigm to two example tasks, contrast discrimination and word categorization, and find dramatically different effects of divided attention. Contrast discrimination has unlimited capacity, consistent with independent, parallel processing. Word categorization has a nearly fixed capacity, consistent with either serial processing or fixed-capacity, parallel processing. We argue that these measures of perceptual capacity rely on relatively few assumptions compared to most alternative measures.     

PandaEPL: A library for programming spatial navigation experiments

Recent advances in neuroimaging and neural recording techniques have enabled researchers to make significant progress in understanding the neural mechanisms underlying human spatial navigation. Because these techniques generally require participants to remain stationary, computer-generated virtual environments are used. We introduce PandaEPL, a programming library for the Python language designed to simplify the creation of computer-controlled spatial-navigation experiments. PandaEPL is built on top of Panda3D, a modern open-source game engine. It allows users to construct three-dimensional environments that participants can navigate from a first-person perspective. Sound playback and recording and also joystick support are provided through the use of additional optional libraries. PandaEPL also handles many tasks common to all cognitive experiments, including managing configuration files, logging all internal and participant-generated events, and keeping track of the experiment state. We describe how PandaEPL compares with other software for building spatial-navigation experiments and walk the reader through the process of creating a fully functional experiment.     

Risk Factors for Attempting Suicide in Prisoners

We wished to examine determinants of suicidal behavior in prisoners. 903 male prisoners had a psychiatric interview which included various psychometric tests. Suicide attempters were compared with prisoners who had never attempted suicide. Significantly more of the attempters had a history of psychiatric disorder, substance abuse, a family history of suicidal behavior, convictions for violent crime, had exhibited aggressive behavior in jail, and had higher BGLHA aggression scores. A similar pattern of risk factors was found for prisoners with suicidal ideation. A lifetime history of attempting suicide, or of having suicidal ideation, is frequent in prisoners. Risk factors include family, developmental, aggression, personality, psychiatric, and substance abuse factors.