Enhancing social diffusion theory as a basis for prevention intervention: A conceptual and strategic framework

Social diffusion theory has recently been recognized as a promising approach for large-scale disease prevention and health promotion efforts. This paper describes how principles and tactics from social cognitive theory, operant psychology, social psychology, social marketing, and the overarching stages of change model can be used to further develop the conceptual and strategic (technological) bases of social diffusion theory. Within an integrative framework, we discuss in detail more effective ways to train peer mediators of behavior change as one example of how social diffusion theory can benefit from this conceptual and strategic reformulation. We then further illustrate the use of peer mediators of change in human immunodeficiency virus (HIV) and cancer prevention intervention studies with both interventions training peer mediators to diffuse information, norms, and risk reduction strategies. Although the results of these studies showed reductions in high-risk behaviors across population segments, more closely following the framework discussed in this article should further increase the behavior change potential of future interventions based on social diffusion theory.     

What did mummy say? Dyadic interactions between young "hard to manage" children and their mothers

Thirty preschoolers rated as hard to manage on Goodman's (R. Goodman, 1997) Strengths and Difficulties Questionnaire (SDQ), and a group of matched control children were observed and recorded on audiotape at home, interacting with their mothers (Time 1). At the 18-month follow-up home visits (Time 2), the children and mothers were filmed across 4 observation settings. Mother–child interactions were rated on affect, control, responsiveness and connectedness of communication. At Time 1, mothers of the hard to manage group used more negative control and engaged in fewer connected conversations than did mothers in the control group. At Time 2, mothers of the hard to manage group displayed higher levels of negative control and lower levels of positive control. These results are discussed in terms of the importance of examining connected communication and different observation contexts when examining dyadic mother–child interactions.     

Two bs or not two Bs? A signal detection theory analysis of repetition blindness in a counting task

Stimulus repetition usually benefits performance. A notable exception is repetition blindness (RB), in which subjects fail to report a repeated stimulus in a rapid serial visual presentation. Theories differ in attributing RB to either perceptual encoding or memory retrieval and to impaired discrimination versus response bias. In the present study, subjects judged whether one or two letters were imbedded in sequences of digits. Unlike previous studies, false guesses of two unrepeated letters were distinguished from false guesses of two repeated letters. When repeated- and unrepeated-letter trials were randomly intermixed (Experiment 1), RB was entirely attributable to response bias. However, when they were separately blocked (Experiments 2 and 3), RB was manifested in discriminability (d'). The results support perceptual-encoding accounts of RB but indicate that effects on discriminability depend on subjects' processing strategies.     

Perceptual assignment of opacity to translucent surfaces: the role of image blur

In constructing the percept of transparency, the visual system must decompose the light intensity at each image location into two components one for the partially transmissivc surface, the other for the underlying surface seen through it. Theories of perceptual transparency have typically assumed that this decomposition is defined quantitatively in terms of the inverse of some physical model (typically, Metelli's 'episcotister model'). In previous work, we demonstrated that the visual system uses Michelson contrast as a critical image variable in assigning transmittance to transparent surfaces not luminance differences as predicted by Metelli's model [F Metelli, 1974 Scientific American 230(4) 90 98]. In this paper, we study the contribution of another variable in determining perceived transmittance, namely, the image blur introduced by the light-scattering properties of translucent surfaces and materials. Experiment 1 demonstrates that increasing the degree of blur in the region of transparency leads to a lowering in perceived transmittance, even if Michelson contrast remains constant in this region. Experiment 2 tests how this addition of blur affects apparent contrast in the absence of perceived transparency. The results demonstrate that, although introducing blur leads to a lowering in apparent contrast, the magnitude of this decrease is relatively small, and not sufficient to explain the decrease in perceived transmittance observed in experiment 1. The visual system thus takes the presence of blur in the region of transparency as an additional image cue in assigning transmittance to partially transmissive surfaces.     

Ethical and practical considerations in managing incidental findings in functional magnetic resonance imaging

Functional magnetic resonance imaging has emerged as a powerful tool for mapping the neurologic underpinnings of sensory, motor and cognitive function. Much of this evolution carries assumptions about the subject population under study and, in particular, the neurologic status of subjects entered into studies either as healthy controls or as belonging to a specific disease group. Recent reports of incidental MRI abnormalities in normal volunteers for fMRI studies have brought to attention a variety of practical challenges and ethical dilemmas for researchers, many of whom are not physicians and most of whom have no formal radiological training. We propose a minimum standard for consenting subjects in fMRI protocols, and consider strategies over the longer term that call for expert physician participation, archiving of incidental findings including false positives, and the adoption of guidelines for handling variation in neural activations or performance that appear outside expected norms.     

Diffusion-tensor imaging of cognitive performance

MR methods have for some years been used to assess cognitive performance. Recently, studies have shown that diffusion-tensor imaging (DTI), which provides noninvasive maps of microscopic structural information of oriented tissue in vivo, is finding utility in studies of cognition in the normal and abnormal aging population. These studies suggest that water proton nonrandom, anisotropic diffusion measured by DTI is highly sensitive to otherwise subtle disease processes not easily seen with conventional MRI tissue contrast mechanisms and raises new issues of the role of MR in assessing cognitive potential.     

"Clockness" in the detection of dementia: a semantic-conceptual effect

We studied aspects of clock cognition that might underlie the sensitivity of the CDT in screening for dementia of the Alzheimer type (DAT). Two groups, 15 patients with mild-moderate DAT and 15 controls, were assessed with the CDT and specially designed tests of clock-related cognition. Patients were impaired on the CDT, but they did not differ from controls in copying a clock face or selecting the correct representation of a given time. Patients were worse than controls at distinguishing between clock and nonclock objects, detecting anomalies in clocks, and in setting time irrespective of response format. These findings suggest that semantic-conceptual aspects of clock-related cognition are important in discriminating between patients with DAT and controls.     

The research subject as wage earner

Theoretical Medicine and Bioethics - The practice of paying research subjects for participating inclinical trials has yet to receive an adequate moral analysis.Dickert and Grady argue for a wage...     

Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life

Two studies examined violent video game effects on aggression-related variables. Study 1 found that real-life violent video game play was positively related to aggressive behavior and delinquency. The relation was stronger for individuals who are characteristically aggressive and for men. Academic achievement was negatively related to overall amount of time spent playing video games. In Study 2, laboratory exposure to a graphically violent video game increased aggressive thoughts and behavior. In both studies, men had a more hostile view of the world than did women. The results from both studies are consistent with the General Affective Aggression Model, which predicts that exposure to violent video games will increase aggressive behavior in both the short term (e.g., laboratory aggression) and the long term (e.g., delinquency).