The scaling of postural adjustments during bimanual load-lifting in traumatic brain-injured adults

Previous postural studies of traumatic brain injury (TBI) patients have been limited to identifying deficits in static and quasi-dynamic postural control tasks such as weight shifting. In this study, we examined whether or not patients with TBI are able to scale adequately their postural adjustments during the performance of the dynamic task of bimanual load-lifting. An age matched group of healthy adults served as controls. We used the Tetrax posturography system that calculates a stability score (ST) based on fluctuations in vertical ground reaction forces, normalized for body weight. During quiet standing, the ST scores of the TBI group were significantly higher than the control group. Forward weight shift and percentage change in the vertical ground reaction forces (lift postural adjustment (LPA) and post-lift postural adjustment (PLPA) scores) linearly increased with increasing load weight in both healthy and TBI subjects. Group differences were found in the magnitude of forward weight shift but not in the relative increase of the LPA and PLPA scores during the lifting and post-lifting phases respectively. The forward weight shift of the TBI group was lower-than-normal and asymmetrical--there was significantly less forward weight shift on the more affected than on the less affected limb. In addition, a significant amplitude coupling was found between the scaling of the weight shift of the heel and forefoot of each limb. However, no coupling was found between the weight shift amplitudes of homologous parts of both limbs in the TBI group. The results showed that scaling based on prior experience was preserved in the TBI group, though some TBI subjects demonstrated absent scaling in either the more affected or less affected heel or forefoot. The differences between the normal and TBI groups in postural adjustments are not necessarily a sign of pathology; rather they may represent a deliberate choice of the central nervous system to counteract predictable disturbances.     

Ethical issues surrounding human participants research using the Internet

The Internet appears to offer psychologists doing research unrestricted access to infinite amounts and types of data. However, the ethical issues surrounding the use of data and data collection methods are challenging research review boards at many institutions. This article illuminates some of the obstacles facing researchers who wish to take advantage of the Internet's flexibility. The applications of the APA ethical codes for conducting research on human participants on the Internet are reviewed. The principle of beneficence, as well as privacy and confidentiality, informed consent, deception, and avoiding harm are all illustrated through the use of a hypothetical online study.     

Phonological memory and vocabulary learning in children with focal lesions

Eleven children with early focal lesions were compared with 70 age-matched controls to assess their performance in repeating non-words, in learning new words, and in immediate serial recall, a triad of abilities that are believed to share a dependence on serial ordering mechanisms (e.g.,; ). Results for the experimental group were also compared with other assessments previously reported for the same children by. The children with brain injury showed substantial impairment relative to controls in the experimental tasks, in contrast with relatively unimpaired performance on measures of vocabulary and non-verbal intelligence. The relationships between word learning, non-word repetition, and immediate serial recall were similar to those observed in several other populations. These results support previous reports that there are persistent processing impairments following early brain injury, despite developmental plasticity. They also suggest that word learning, non-word repetition, and immediate serial recall may be relatively demanding tasks, and that their relationship is a fundamental aspect of the cognitive system.     

Chunking versus foraging search patterns by rats in the hierarchically baited radial maze

Rats were exposed to a radial maze containing six black smooth arms and six wire-grid-covered arms and a striped 'exit arm' in experiment 1. The probability of a black or grid arm being baited (5/6 vs 1/6) with sunflower seeds was associated with its proximal cue for some rats (the Relevant Arm Cue group) but not for others (the Irrelevant Arm Cue group). All rats could terminate a trial and receive a highly preferred morsel of apple by entering the exit arm only after having sampled all six seed-baited arms. Relevant Arm Cue rats usually chose some arms from the more densely baited set before choosing an arm from the less densely baited set and made fewer reentries than Irrelevant Arm Cue rats. Although such clustered, higher choice accuracy in the Relevant Arm Cue group corresponds to human clustered, better recall of verbal items from lists hierarchically organized by categories, these rats did not similarly exhaustively retrieve items (arm locations). That is, when required to terminate a trial by entering the 'exit' arm for an apple morsel after having sampled all seed-baited arms, both groups were equally unable to withhold making nonrewarded premature exits. This nonexhaustive foraging search pattern was maintained in the next two experiments in which the radial maze was reduced to three black and three grid arms along with the striped 'exit' arm and in which black and grid arm cues were paired with number of seeds (eight or one) in an arm for Relevant Arm Cue rats. Although Relevant Arm Cue rats displayed perfect clustering by entering all eight-seeded arms before a one-seeded arm, they made more premature exits and reentries into eight-seeded arms in experiment 2 or when forced to enter all eight-seeded arms in experiment 3 than did Irrelevant Arm Cue rats. These foraging tendencies prevent accurate estimations of the amount of information (i.e., arm locations) rats can 'chunk'. Electronic Publication     

The impact of character attribution on composite production: A real world effect?

Facial memory draws upon both veridical detail and beliefs based upon prior knowledge and stereotypes. Shepherd, Ellis, McMurran, and Davies (1978) demonstrated that subjects' perception and subsequent reconstruction of a face using the “Photofit” kit was significantly influenced by whether they believed the person to be a multiple murderer or a local hero. The current study explored whether similar effects would occur when the face involved was one of four male celebrities about which subjects held pronounced positive or negative views and where reconstruction was accomplished using the computerised “E-fit” composite system. Semantic differential ratings showed significant influences of liking on subjects' perception and reconstruction of the faces involved, though the pattern of effects was not always readily predictable. Liking also influenced accuracy of reconstruction; ranking and naming data showed that the best composites were made by subjects who disliked the target and made their reconstructions with the aid of a photograph.     

The impact of character attribution on composite production: A real world effect?

Facial memory draws upon both veridical detail and beliefs based upon prior knowledge and stereotypes. Shepherd, Ellis, McMurran, and Davies (1978) demonstrated that subjects' perception and subsequent reconstruction of a face using the “Photofit” kit was significantly influenced by whether they believed the person to be a multiple murderer or a local hero. The current study explored whether similar effects would occur when the face involved was one of four male celebrities about which subjects held pronounced positive or negative views and where reconstruction was accomplished using the computerised “E-fit” composite system. Semantic differential ratings showed significant influences of liking on subjects' perception and reconstruction of the faces involved, though the pattern of effects was not always readily predictable. Liking also influenced accuracy of reconstruction; ranking and naming data showed that the best composites were made by subjects who disliked the target and made their reconstructions with the aid of a photograph.     

Exposure to Media Images of Female Attractiveness and Concern with Body Weight Among Young Women1

Despite the popular belief that the thinstandard of female attractiveness currently presented inthe media is a primary contributor to the high level ofconcern with body weight among women, experimental studies have not shown that exposure to mediaimages increases women's weight concern. Threeexperiments are reported demonstrating that exposure tomedia images does often result in increased weightconcern among women, but that body dissatisfaction, astable personality characteristic, is a moderator ofvulnerability to this effect. Although most womenreported higher weight concern when exposed to media vs. neutral images, women with low initial bodydissatisfaction did not. In addition, this researchsuggests that negative effects on weight concern mayresult from even passive exposure to media images, but that exposure to realistic attractivenessis less likely to cause increased weight concern. Theethnicity of the participants in these studies reflectedthat of the local population, with over 90% white. The nonwhite participants primarily belonged toone of the following groups; Asian, Pacific Islander,Latino.     

Effects of High-Probability Request Sequences on Preschoolers' Compliance and Disruptive Behavior

A high-probability request sequence was implemented with three preschool children with developmental delays within their classroom during typical activities. A multiple baseline design across subjects was used to evaluate the effects of the high-probability request sequence on compliant responding to low-probability requests and the occurrence of disruptive behavior. Results of the study indicate that the use of the high-probability request sequence was effective in increasing compliant responding to low-probability requests delivered by two different trainers for all children. No increases in disruptive behavior were noted as a result of using the high-probability request sequence. When the high-probability request sequence was withdrawn, compliant responding to low-probability requests was maintained for all children across time and in different settings.