Visual noise reveals category representations

How are categories represented in human memory? Exemplar models assume that a category is represented by individual instances from that category that have been experienced. More generally, a category might be represented by multiple templates stored in memory. A new item is classified according to its similarity to these templates.Prototype models represent a category with a single summary abstraction (i.e., a single template), often the central tendency of the experienced items. A new item is classified according to its similarity to these category prototypes. Here, we show how a technique for correlating observers’ responses with external noise can be used not only to distinguish single- from multiple-template representations, but also to induce the form of these templates. The technique is applied to two tasks requiring categorization of simple visual patterns; the results demonstrate that observers used multiple traces to represent their categories, and thus highlight the procedure’s potential for use in more complex settings.     

Visual memory decay is deterministic

After observers see an object or pattern, their visual memory of what they have seen decays slowly over time. Nearly all current theories of vision assume that decay of short-term memory occurs because visual representations are progressively and randomly corrupted as time passes. We tested this assumption using psychophysical noise-masking methods, and we found that visual memory decays in a completely deterministic fashion. This surprising finding challenges current ideas about visual memory and sets a goal for future memory research: to characterize the deterministic "forgetting function" that describes how memories decay over time.     

Adrenocortical reactivity and social competence in seven year-olds

We examined temporal changes in salivary cortisol in response to a peer self-presentation task in a group of seven year-olds, some of whom scored high, average, and low on the Harter, 1983 Perceived Social Competence Scale. Salivary cortisol was measured pre-task, and 20 and 35 min post-task. We found a significant relation between individual differences in perceived social competence and salivary cortisol reactivity in response to the task. Children who perceived themselves as socially competent exhibited a significantly greater decrease in salivary cortisol from 20 to 35 min following the task compared with children who self-reported a relatively lower degree of social competence. We speculate on the meaning of salivary cortisol changes in childrens socio-emotional development.     

Risk of sexual revictimization: A theoretical model

Survivors of child sexual abuse suffer serious short- and long-term psychological consequences. Sexual revictimization as an adult is one of the consequences that has been reported. At present, there is no theoretical model identifying the risk factors that result in child sexual abuse survivors being at greater risk of experiencing an adult sexual assault. The proposed model is designed to integrate existing research, stimulate further empirical work, and eventually aid in the development of a program to prevent revictimization. The variables hypothesized to play a mediating role in the pathway to revictimization include: severe psychological symptoms as a consequence of the child sexual abuse, poor coping styles, an insecure attachment style, hyperfemininity, delinquent behavior, drug use, and high risk sexual behavior.     

Factor Structure of the School Reinforcement Survey Schedule: School Is More Than Grades

The School Reinforcement Survey Schedule (SRSS) was administered to 5913 4th through 12th graders as part of an evaluation component of the University of South Carolina's Institute for Families in Society's School-Based Mental Health Project. A factor analysis of SRSS responses yielded six interpretable factors. Gender differences in responses showed that girls, as opposed to boys, find a wider variety of reinforcers associated with school to be pleasurable. A significant, but small, correlation was found between grades and school reinforcement.     

Attraction to a dissimilar stranger as a function of level of effectance arousal

An experiment was carried out to demonstrate that the relationship between attitudes of a stranger and attraction to that stranger can be mediated by effectance arousal and the consequent information search to reduce the arousal. The argument posited was that individuals under high effectance arousal produced by a confusing and ambiguous film would be attracted to dissimilar others as a source of information and uncertainty reduction. Results indicated that high levels of arousal produced greater attraction to a dissimilar stranger than to a similar stranger. This finding was reversed when an explanation was provided along with the confusing film, lending support to the uncertainty reduction position.     

Automated assessment of conditioning parameters for context and cued fear in mice

A behavioral technique often used to evaluate the cognitive performance of rats and mice is the fear conditioning paradigm. During conditioned fear experiments, freezing responses shown by rodents after exposure to environmental stimuli previously paired to an aversive experience provide a behavioral index of the animal's associative abilities. The present study examined the ability of a computer-controlled automated Freeze Monitor system for recording immobility behavior in mice. The sensitivity of the automated procedure to detect group differences caused by the application of various training protocols was also evaluated. Statistical analyses revealed significant positive correlations between immobility scores obtained with the automated apparatus and hand-scored data collected by a continuous or a time-sampling method. Behavioral patterns recorded by the computerized system were very similar to those obtained by the hand-scoring methods adopted. In particular, during context testing, exposure to environmental stimuli previously paired with a mild foot shock (unconditioned stimulus [US]) evoked increased immobility behavior in mice conditioned with the US compared with levels of immobility displayed by mice previously confined to the same contextual stimuli without receiving the US. Moreover, although during conditioned stimulus (CS) testing, mice previously exposed to the US displayed high levels of immobility when confined to environmental cues much different from those paired with the US (contextual fear generalization), both hand-scored and automated results revealed the effect of CS–US pairing (increased immobility) only in mice trained to associate the two stimuli (paired group) but not in mice exposed to both CS and US separated by a 40-sec time interval (unpaired group) or in mice receiving only the US (US group) during conditioning sessions. Overall, the results show associative conditioning measured in an automated apparatus and highlight the utility of obtaining both latency as well as beam interruption parameters.     

Bayesian Risk Assessment in Genetic Testing for Autosomal Dominant Disorders with Age-Dependent Penetrance

Risk assessment is an essential component of genetic counseling and testing, and the accuracy of risk assessment is critical for decision making by consultands. However, it has been shown that genetic risk calculations may have high error rates in practice. Risk calculations for autosomal dominant disorders are frequently complicated by age-dependent penetrance and sensitivities of less than 100% in genetic testing. We provide methods of risk calculation for prototypical pedigrees of a family at risk for an autosomal dominant disorder with age-dependent penetrance. Our risk calculations include scenarios in which the sensitivity of genetic testing is less than 100%, and in which the sensitivity of genetic testing varies for different family members at risk. Our Bayesian methods permit autosomal dominant disease probabilities to be calculated accurately, taking into account all relevant information. Our methods are particularly useful for hereditary cancer syndromes, in which genetic testing can seldom achieve 100% sensitivity. Our methods can be applied to many different scenarios, including those where the sensitivity of genetic testing varies for different family members at risk. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.     

The neurobiology of virtual reality pain attenuation.

During the past decade, virtual reality (VR) has gained recognition as a means of attenuating pain during medical procedures. However, while investigators have examined the effects of virtual environments on level of distraction, subjective pain intensity, and brain activity, there have been only a handful of investigations into the neurobiological mechanisms associated with VR's efficacy. In an effort to explain how VR may alter pain perception and produce analgesia, as well as to guide the development of novel and improved VR pain treatments, this review aims to link the wealth of empirical data examining the neurobiology of pain to the growing field of VR. This review is separated into three main sections: (a) a brief overview of the current literature on the use of VR for the treatment of pain; (b) a review of the basic neurobiology of how pain is detected, processed, and controlled by the brain; and (c) an exploration into how current VR pain treatments may impact the pain system to produce analgesia. In addition, the future of VR for pain treatment is discussed, including how current treatments might be improved and novel ways to use VR to treat pain might be developed. Speculation on future VR interventions is based on our current understanding of how the brain processes pain and how VR appears to alter this process and produce analgesia.