Main and interaction effects of metallic toxins on classroom behavior

This study investigated the relationships of metal levels and metal combinations to children's classroom behavior. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 80 randomly selected elementary-age children, who were also rated by their classroom teacher on the Walker Problem Behavior Identification Checklist (WPBIC). Parents were interviewed to control for confounding variables that may have affected behavioral development. Regression analysis indicated that the set of metals was significantly related to increased scores on four of the five WPBIC subscales and on the total scale, with lead being a major contributor to four of the six dependent measures. Metal combinations were significantly related to increased scores on the WPBIC subscales measuring acting-out, disturbed peer relations, and immaturity, and on the total scale. A continuing reexamination of metal poisoning concentrations is needed because metal levels and metal combinations previously thought harmless may be associated with nonadaptive classroom behavior.     

Developmental cognitive neuroscience: progress and potential

Developmental cognitive neuroscience is an evolving field that investigates the relations between neural and cognitive development. Lying at the intersection of diverse disciplines, work in this area promises to shed light on classic developmental questions, mechanisms subserving developmental change, diagnosis and treatment of developmental disorders, and cognitive and neuroscientific topics traditionally considered outside the domain of development. Fundamental questions include: What are the interrelations between developmental changes in the brain (e.g. in connectivity, chemistry, morphology) and developmental changes in children's behavior and cognitive abilities (e.g. representational complexity, ability to sustain selective attention, speed of processing)? Why, and how, is learning enhanced during certain periods in development? How is our knowledge organized, and how does this change with development? We discuss preliminary investigations of such questions and directions for future work.     

The race model inequality: interpreting a geometric measure of the amount of violation

An inequality by J. O. Miller (1982) has become the standard tool to test the race model for redundant signals reaction times (RTs), as an alternative to a neural summation mechanism. It stipulates that the RT distribution function to redundant stimuli is never larger than the sum of the distribution functions for 2 single stimuli. When many different experimental conditions are to be compared, a numerical index of violation is very desirable. Widespread practice is to take a certain area with contours defined by the distribution functions for single and redundant stimuli. Here this area is shown to equal the difference between 2 mean RT values. This result provides an intuitive interpretation of the index and makes it amenable to simple statistical testing. An extension of this approach to 3 redundant signals is presented.     

Conditions under which young children can hold two rules in mind and inhibit a prepotent response

The day-night task requires saying "night" to a picture of the sun and "day" to a picture of the moon. In this investigation of why young children fail at this task, systematic variations of the task were administered to 96 children, half 4 years old and half 4 1/2 years old. Training children on the strategy of chunking the 2 rules into I ("say the opposite"), thus reducing memory load, did not help their performance. What helped was reducing the inhibitory demand by instructing them to say "dog" and "pig" (not "night" and "day") even though memory of 2 rules and inhibiting saying what the pictures represented were still required. Here the response to be activated and the response to be inhibited were unrelated. When the correct response was semantically related to, and the direct opposite of, the to-be-inhibited response, children performed poorly. Inserting a delay between stimulus and response helped even though that delay was filled with distraction. Young children apparently need several seconds to compute the answer on this task. Often they do not take the needed time; when forced to do so, they do well.     

Modeling spatial effects in visualtactile saccadic reaction time

Saccadic reaction time (SRT) to visual targets tends to be shorter when nonvisual stimuli are presented in close temporal or spatial proximity, even when subjects are instructed to ignore the accessory input. Here, we investigate visualtactile interaction effects on SRT under varying spatial configurations. SRT to bimodal stimuli was reduced by up to 30 msec, in comparison with responses to unimodal visual targets. In contrast to previous findings, the amount of multisensory facilitation did not decrease with increases in the physical distance between the target and the nontarget but depended on (1) whether the target and the nontarget were presented in the same hemifield (ipsilateral) or in different hemifields (contralateral), (2) the eccentricity of the stimuli, and (3) the frequency of the vibrotactile nontarget. The time-window-of-integration (TWIN) model for SRT (Colonius & Diederich, 2004) is shown to yield an explicit characterization of the observed multisensory spatial interaction effects through the removal of the peripheral-processing effects of stimulus location and tactile frequency.     

Responses of dairy heifers to the visual cliff formed by a herringbone milking pit: evidence of fear of heights in cows (Bos taurus)

The ability of cows (Bos taurus) to perceive depth has never been experimentally investigated. If cows can perceive depth, the milking pit in commercial milking facilities may be fear provoking for dairy cows, as past research has shown that most land-dwelling species possess an instinctive fear of heights. In the current study, 12 dairy heifers (1-year-old cows) were exposed to a milking pit (depth-exposed group) and 13 heifers (control group) were exposed to a standard change in the environment while they moved through a milking facility over a 5-day treatment period. Heifers in the depth-exposed group showed a higher heart rate (p < .05) and stopped more often (p < .05) than did those in the control group; persistence of heart rate but not of behavioral responses on repeated exposures indicated that some habituation to the depth stimulus had occurred. Depth exposure had no effect on cortisol concentrations or on ease of handling. These results indicate that heifers responded differently to a change in depth than they did to a standard change in the environment and provide evidence of both depth perception and acute fear of heights in cows.     

Personality Trait Differences Between Young and Middle‐Aged Adults: Measurement Artifacts or Actual Trends?

A growing body of research demonstrates that older individuals tend to score differently on personality measures than younger adults. However, recent research using item response theory (IRT) has questioned these findings, suggesting that apparent age differences in personality traits merely reflect artifacts of the response process rather than true differences in the latent constructs. Conversely, other studies have found the opposite—age differences appear to be true differences rather than response artifacts. Given these contradictory findings, the goal of the present study was to examine the measurement equivalence of personality ratings drawn from large groups of young and middle‐aged adults (a) to examine whether age differences in personality traits could be completely explained by measurement nonequivalence and (b) to illustrate the comparability of IRT and confirmatory factor analysis approaches to testing equivalence in this context. Self‐ratings of personality traits were analyzed in two groups of Internet respondents aged 20 and 50 (n = 15,726 in each age group). Measurement nonequivalence across these groups was negligible. The effect sizes of the mean differences due to nonequivalence ranged from –.16 to .15. Results indicate that personality trait differences across age groups reflect actual differences rather than merely response artifacts.     

Generality of the practical functional assessment and skill‐based treatment among individuals with autism and mental health disorders

A practical functional assessment format was recently developed that informed a skill‐based treatment for the problem behavior of children diagnosed with autism spectrum disorder. Since its inception there have been multiple replications of the procedures; however, the comprehensive model has rarely been applied to populations with more complex comorbid disorders and severe problem behavior such as those diagnosed with anxiety or depression. We conducted the current study to systematically replicate the entire practical functional assessment and skill‐based treatment model with two participants diagnosed with multiple mental health disorders admitted to a severe behavior outpatient unit. The practical functional assessment identified reinforcers that were provided contingent on increasingly complex forms of communication. Problem behavior remained low for both participants after reinforcement was thinned by increasing a response requirement of completing difficult tasks. Furthermore, the results were socially validated by the parents and teachers and the treatment was extended to the home setting.     

Stigma and the delegitimation experience: An interpretative phenomenological analysis of people living with chronic fatigue syndrome

Individual in-depth interviews with 14 people with chronic fatigue syndrome (CFS) were conducted, focusing on the experience of living with CFS. The interviews were transcribed verbatim and were analysed for recurrent themes using interpretative phenomenological analysis (IPA). Here we present two inter-related themes: “Negotiating a diagnosis” and “Negotiating CFS with loved ones”. Participants reported delay, negotiation and debate over diagnosis: further, they perceived their GPs to be sceptical, disrespectful and to be lacking in knowledge and interpersonal skills. However, participants found delegitimising encounters with their partners more difficult to deal with. Participants viewed such delegitimation as a form of personal rejection; they were hurt by their loved ones’ reactions and subsequently pondered the price of love, respect and friendship. The findings are discussed in relation to extant literature, and recommendations for future research are suggested.