Methylphenidate and cognitive flexibility: Dissociated dose effects in hyperactive children

A randomized, double-blind, placebo-controlled trial was conducted to assess the acute effects of placebo and three doses of methylphenidate (MPH) (0.3, 0.6, 0.9 mg/kg) on cognitive flexibility and overt behavior in 28 children with a confirmed diagnosis of attention deficit-hyperactivity disorder. Two underlying cognitive processes (response inhibition and response reengagement) were assessed by measuring the probability and speed with which subjects could inhibit responses to a primary task (forced-choice letter discrimination) and immediately execute a response to a secondary task (simple reaction time) when given a signal to do so. Results indicated that MPH enhanced cognitive flexibility, although the high dose was less effective than lower doses in enhancing response inhibition. Dissociations of dose effects on cognitive function and behavior were demonstrated: Dose-response functions for changes in behavior were linear, whereas the function for response inhibition was U-shaped. Findings argue against the typical clinical practice of determining the response to stimulant treatment from a single measure such as parent report of child behavior.     

Observer Perceptions of Chronic Low Back Pain1

This study examined the effects of three variables on perceptions of symptoms associated with chronic low back pain: (a) the presence or absence of supporting medical evidence, (b) the valence (positive/negative) of the relationship of an observer to the person in pain, (c) the degree of control (present/absent) of the person in pain over the circumstances of pain onset. The independent variables were manipulated in a (2 × 2 × 2) within-subjects design. Forty-eight undergraduate subjects were asked to estimate levels of pain intensity, emotional distress, and disability for the person in pain described in each of eight vignettes. Significant main effects, a two-way interaction, and a three-way interaction emerged, indicating that these contextual variables exerted substantial and complex effects on observer perceptions. The implications of these findings are discussed for matters such as pain assessment and disability determination.     

Retroactive raising of a sensory threshold by a contralateral stimulus

In an experiment designed to extend Howarth and Treisman's recent observations on the lowering of the visual and auditory threshold produced by a warning stimulus, it has been found that the threshold to electrical stimulation of one forearm is raised by a similar stimulus on the other forearm. As in the earlier experiments the “warning” was effective if it came 100 millisec. before or after the threshold stimulus. The effect increased with increasing warning strength over the range of five near-threshold strengths used.

These results appear to be inconsistent with the explanation previously proposed to account for the retroactive lowering of threshold. This suggested that the warning was acting simply as a marker, reducing the subject's uncertainty as to when the stimulus was coming. The fact that the rise in threshold was also induced retroactively shows that some interaction must be occurring in the central processes concerned in perception, and that it cannot be explained in terms of attenuation of the afferent volley.     

The stability of binocular rivalry during spaced and massed viewing

Attention, Perception, & Psychophysics - The purpose of the study was consideration of the stability of binocular rivalry rates during extended periods of spaced and massed viewing by untrained...     

Empathy and Social Perspective Taking in Children with Attention-Deficit/Hyperactivity Disorder

This study explored empathy and social perspective taking in 8 to 12 year old children with and without Attention-Deficit/Hyperactivity Disorder (ADHD). The sample comprised 92 children, 50 with a diagnosis of ADHD and 42 typically developing comparison children. Although children with ADHD were rated by their parents as less empathic than children without ADHD, this difference was accounted for by co-occurring oppositional and conduct problems among children in the ADHD sample. Children with ADHD used lower levels of social perspective taking coordination in their definition of problems, identification of feelings, and evaluation of outcomes than children without ADHD, and these differences persisted after the role of language abilities, intelligence and oppositional and conduct problems were taken into account. Girls were more empathic and had higher overall social perspective taking scores than boys. Implications for research and practice are discussed. This research was funded by the Social Sciences and Humanities Research Council (SSHRC).     

The influence of object conceptions on the mechanical intuitions of children and adults

This research examines how initial conceptualizations of objects and space exert an influence on predictions about the physical world but simultaneously lead the naïve to misconstrue a dynamic event. In four investigations, children (kindergartners, third graders, and sixth graders) and adults predicted where an oscillating screen would contact an object occluded by the screen's motion, a task adapted from the infant literature which is used to assess early knowledge of the solidity constraint on object motion. Participants demonstrated remarkable proficiency in anticipating the point of contact despite the formal geometric complexity of the event. However, although predictions were close approximations of the parameters objectively determinable for the event, responses were universally biased; participants systematically underestimated the distance the screen would travel to contact the object. Participants' responses were never in violation of the principle: One object cannot pass into the space occupied by another. Children and adults used different strategies to achieve their predictions, so the pattern of misconstruals across task parameters were developmentally related; however, the direction of the misconstrual was developmentally invariant. The findings are evaluated in terms of how initial knowledge of objects constrains intuition about physical events.     

Cortisol reactivity and regulation associated with shame responding in early childhood

The purpose of this study was to characterize cortisol response and regulation associated with shame responding in early childhood and to examine how general the relation between shame and cortisol is. It was predicted that children responding to task failure with shame would show a larger and more prolonged cortisol response than other children. Participants were 214 children (124 boys, 90 girls) ranging from 3.7 to 4.5 years of age (M = 4.14 years, SD = 0.24). Shame responding was assessed from children's emotion-expressive behavior in response to failing 6 performance tasks, 2 preceding (initial) and 4 following (subsequent) assessment of hypothalamic-pituitary-adrenal axis activation. Cortisol response and regulation associated with failure were assessed from saliva sampled before and 15, 20, 25, 30, and 40 min following the first of the 2 initial failures. For boys and for some girls, high initial shame was associated with greater cortisol reactivity and slower regulation of the cortisol response. For boys, high initial shame and relatively slow regulation of the associated cortisol response predicted subsequent shame responding occurring after recovery of the cortisol response. For girls, high initial shame, but not cortisol response, predicted subsequent shame responding. (PsycINFO Database Record (c) 2008 APA, all rights reserved).     

Women showing off: notes on female exhibitionism

The limitations of the phallocentric cast of earlier psychoanalytic formulations of "female exhibitionism" linger into the present. In part this connects to certain historical expectations for women's social behavior, and to the vicissitudes of Freud's insufficient knowledge of women in his libidinal psychosexual phasing used as a basis for analytic understanding. The contemporary fade of libido theory contributes to the neglect of such topics as they relate to the biological body. Yet ease and conflict regarding conscious and unconscious female body image representations related to that stepchild of theory-pregnancy and childbirth in particular-play a major role in female body display. Recognition of such body fantasies and female body meanings from early childhood into maturity tends to be marginalized within all of the psychoanalytic theories current today. The focus here on female exhibitionism suggests a normative spectrum for pleasurably active sex seeking and pleasurable procreative desire and fantasy that is present in a female's use of her body and which (of course, but secondarily) can become caught up in conflict. Two cases accenting analyses of female "showing off" behavior are included.     

Interactions between mothers and infants: impact of maternal anxiety

The aim of the study was to examine the impact of anxiety in the postnatal year on maternal contribution to mother-infant interaction. Participants were 32 mothers with high anxiety and 32 mothers with low anxiety, when their infants were aged 10-14 months. Mother-infant interaction was videotaped during a standardized play situation and coded blind to group status. High trait anxiety mothers showed less sensitive responsivity (p<.05) and reduced emotional tone (p<.05) during interaction. When participants scoring high in depressive symptomatology were removed for a subgroup analysis, the same pattern of results was obtained, suggesting that the observed differences in mother-infant interaction were due to group differences in anxiety.