Effect of visual surrounding motion on body sway in a three-dimensional environment

Unidirectional motion of a uniplanar background induces a codirectional postural sway. It has been shown recently that fixation of a stationary foreground object induces a sway response in the opposite direction (Bronstein & Buckwell, 1997) when the background moves transiently. The present study investigated factors determining this contradirectional postural response. In the experiments presented, center of foot pressure and head displacements were recorded from normal subjects. The subjects faced a visual background of 2 x 3 m, at a distance of 1.5 m, which could be moved parallel to the interaural axis. Results showed that when the visual scene consisted solely of a moving background, the conventional codirectional postural response was elicited. When subjects were asked to fixate an earth-fixed foreground (window frame) placed between them and the moving background, a consistent postural response in the opposite direction to background motion was observed. In addition, we showed that this contradirectional postural response was not transient but was sustained for the 11 sec of background motion. We investigated whether this contradirectional postural response was the consequence of the induced movement of the foreground by background motion. Although induced movement was verbally reported by subjects when viewing an earth-fixed target projected onto the moving background, the contradirectional sway did not occur. These results indicate that foreground-background separation in depth was necessary for the contradirectional postural response to occur rather than induced movement. Another experiment showed that, when the fixated foreground was attached to the head of the observer, the contradirectional sway was not observed and was therefore unrelated to vergence. Finally, results showed that the contradirectional postural response was, in the main, monocularly mediated. We conclude that the direction of the postural sway produced by a moving background in a three-dimensional environment is determined primarily by motion parallax.     

BDNF serum levels in subjects developing or not post-traumatic stress disorder after trauma exposure

Post-traumatic stress disorder (PTSD) is a syndrome resulting from exposure to a severe traumatic event that poses threatened death or injury and produces intense fear and helplessness. The neural structures implicated in PTSD development belong to the limbic system, an important region for emotional processing. Brain-derived neurotrophic factor (BDNF) is a neurotrophin that serves as survival factor for selected populations of central nervous system (CNS) neurons and plays a role in the limbic system by regulating synaptic plasticity, memory processes and behavior. Impaired BDNF production in the brain can lead to a variety of CNS dysfunctions including symptoms associated with PTSD. However, so far fewer studies have investigated this neurotrophin in patients with PTSD. Furthermore, given the multiple role of BDNF in various CNS disorders, it cannot be excluded that traumatic events per se may influence neurotrophin levels, without a direct association to the PTSD syndrome.     

No dual-task practice effect in Alzheimer's disease

Diagnosis of Alzheimer's disease (AD) requires evidence of progressive decline in cognitive function. However, many tests used to assess cognitive function suffer from considerable practice effects, reducing their reliability. Several studies have reported that the ability to do two things at once, or dual tasking, is impaired in AD, but unaffected by healthy ageing. The apparent specificity of this impairment suggests that this assessment may be particularly useful in the early diagnosis of AD, but the reliability of this assessment remains unknown. Therefore, this study investigated simultaneous performance of digit recall and tracking tasks across six testing sessions in eight people with AD, eight healthy older adults and eight healthy younger adults. The results found that dual-task performance was unaffected by healthy ageing, but significantly impaired in AD, with no effect of repeated exposure. The absence of any improvements in performance despite increased familiarity with the task's demands suggests that not only is the dual-task assessment well suited for monitoring progression over time, but also that dual tasking involves a specific cognitive function which is impaired in the AD brain.     

The Relationship Between Parenting Style and Children's Adjustment: The Parents' Perspective

We examined the relationship between authoritative and authoritarian parenting styles and socio-emotional adjustment in elementary school children as reported from the parents' perspective. Mothers of first through fifth graders provided information about parenting style as well as children's competencies and problem behaviors. Teachers provided ratings of children's adjustment for a subset of the participants. Results indicated that authoritative parenting was associated negatively with parent- and teacher-rated maladaptive behavior, and positively with indicators of healthy adjustment. Correlations between authoritarian parenting and adjustment were either small or non-significant. Regression analyses indicated that authoritative parenting was more predictive of children's competence than maladaptation (22% versus 10% of variance). The effects of parenting style on adjustment were not moderated by demographic variables, such as the child's gender, grade level, ethnicity, and family income.     

Making treatment effect inferences from multiple-baseline data: The utility of multilevel modeling approaches

Multiple-baseline studies are prevalent in behavioral research, but questions remain about how to best analyze the resulting data. Monte Carlo methods were used to examine the utility of multilevel models for multiplebaseline data under conditions that varied in the number of participants, number of repeated observations per participant, variance in baseline levels, variance in treatment effects, and amount of autocorrelation in the Level 1 errors. Interval estimates of the average treatment effect were examined for two specifications of the Level 1 error structure (σ² I and first-order autoregressive) and for five different methods of estimating the degrees of freedom (containment, residual, between—within, Satterthwaite, and Kenward—Roger). When the Satterthwaite or Kenward—Roger method was used and an autoregressive Level 1 error structure was specified, the interval estimates of the average treatment effect were relatively accurate. Conversely, the interval estimates of the treatment effect variance were inaccurate, and the corresponding point estimates were biased.     

Connecting with New Audiences: Exploring the Impact of Mobile Communication Devices on the Experiences of Young Adults in Museums

Museums worldwide have embraced digital technology and social media in their exhibitions and marketing, yet many discourage visitors' use of mobile communication devices (MCDs), claiming this detracts from the learning experience. This study was guided by mindfulness theory from social cognitive psychology which provides a framework for studying attention, engagement, and learning. It explored the museum experiences of 58 young adults under three experimental conditions—a control group who visited an exhibition with no instructions, a no-MCD group who surrendered all MCDs on entry, and a directed MCD group given guidance on how to use their MCD including taking photographs. The no-MCD group spent significantly less time in the exhibition and had the lowest scores for mindfulness and perceived learning. The directed MCD group spent significantly longer in the exhibition and at exhibits with more text and had the highest scores for mindfulness and perceived learning. This group also took more and different photographs in the exhibition than did the control group. Implications for museum design and MCD policy are outlined.     

The relationship between pitch and space in congenital amusia

Congenital amusia manifests as a lifelong difficulty in making sense of musical sound. The extent to which this disorder is accompanied by deficits in visuo-spatial processing is an important question, bearing on the issue of whether pitch processing draws on supramodal spatial representations. The present study assessed different aspects of visuo-spatial processing with a range of tasks (Shepard-Metzler Mental Rotation, Corsi Blocks Task, Visual Patterns Test) in 14 amusics and matched controls. The absence of a group difference on any of these tasks fails to support a previous claim that the disorder is strongly related to deficits in spatial processing. However, a subgroup of amusics, with significantly elevated thresholds on a pitch direction discrimination task relative to the rest of the group, were slower, but equally accurate, at Mental Rotation. This finding is discussed in relation to the nature of supramodal representations of contour and strategies for dynamic mental transformation.     

Film review

Lucy, 21 months, in foster care for 19 days(Film series and guide-book, Young Children in Brief Separation obtainable from Concord Films Council, Nacton, Ipswich, Suffolk, U.K.).     

Pseudoneglect in back space

Successful interaction with the environment depends upon our ability to retain and update visuo-spatial information of both front and back egocentric space. Several studies have observed that healthy people tend to show a displacement of the egocentric frame of reference towards the left. However representation of space behind us (back space) has never been systematically investigated in healthy people. In this study, by means of a novel visual imagery task performed within a virtual reality environment, we found that representation of right back space is perceived as smaller than the left. These results suggest that there is a selective compression or distortion for mental representation related to the right space behind us.     

Musical expertise has minimal impact on dual task performance

Studies investigating effect of practice on dual task performance have yielded conflicting findings, thus supporting different theoretical accounts about the organisation of attentional resources when tasks are performed simultaneously. Because practice has been proven to reduce the demand of attention for the trained task, the impact of long-lasting training on one task is an ideal way to better understand the mechanisms underlying dual task decline in performance. Our study compared performance during dual task execution in expert musicians compared to controls with little if any musical experience. Participants performed a music recognition task and a visuo-spatial task separately (single task) or simultaneously (dual task). Both groups showed a significant but similar performance decline during dual tasks. In addition, the two groups showed a similar decline of dual task performance during encoding and retrieval of the musical information, mainly attributed to a decline in sensitivity. Our results suggest that attention during dual tasks is similarly distributed by expert and non-experts. These findings are in line with previous studies showing a lack of sensitivity to difficulty and lack of practice effect during dual tasks, supporting the idea that different tasks may rely on different and not-sharable attentional resources.