Postural stability and hand preference as constraints on one-handed catching performance in children

Effects of postural state and hand preference as constraints on 1-handed catching performance were investigated in different ability groups of children aged 9-10 years. On the basis of pretest data, the authors classified 48 participants into groups of good, intermediate, and poor catchers (n = 16 in each) and asked them to perform 1-handed catches with their preferred and nonpreferred hands while standing and sitting. The good catchers' performance was not affected by the imposed postural constraints but did improve when they used the preferred hand. A similar effect of hand preference was evident in the intermediate and poor catchers, but there was also an effect of postural constraint. Independent of hand preference, intermediate catchers' performance while seated improved significantly compared with that during standing. For poor catchers, there was an interaction between hand preference and posture; significant improvement was evident only when they used the preferred hand in the sitting condition. The finding that manipulation of posture and hand preference affected performance outcomes indicates that perceptual skill is not the only influence on catching performance in children. Manipulation of those key constraints may facilitate the acquisition of catching skill, but more research is needed to determine the permanence of those effects.     

Self-enhancement among high-exposure survivors of the September 11th terrorist attack: resilience or social maladjustment?

The authors examined self-enhancing bias as a predictor of adjustment among individuals in or near the World Trade Center during the September 11, 2001, terrorist attacks. Resilience was defined from categorical and continuous analyses of both participant self-report and friend and relative ratings of adjustment. Self-enhancement was associated with a resilient outcome, ratings of better adjustment prior to September 11th, greater positive affect, and reduced perceptions of social constraints. Additional analyses indicated that self-enhancers' reduced symptom levels were fully mediated by their low perceived social constraints. However, consistent with previous evidence suggesting a social cost to self-enhancement, at 18 months post-September 11th, self-enhancers' friends and relatives also rated them as decreasing in social adjustment and as being less honest.     

Effect of orienting the finger opposition space in the control of reach-to-grasp movements

Participants (N = 13) made reach-to-grasp movements to an elongated object with or without a forearm pronation movement. Grasp and transport components of movements performed without forearm pronation differed from those performed when participants preplanned forearm pronation. The transport distance traveled after peak aperture (aperture closure distance) was unchanged, however, suggesting that participants initiated aperture closure on the basis of the distance of the hand from the target. When they suddenly pronated the forearm in response to a perturbation, aperture kinematics were altered from a monophasic to a biphasic profile and aperture closure distance was shortened. Conversely, a sudden reorientation to a nonpronated position minimized those changes. Thus, the relationship between transport and aperture components is differentially altered depending on online reorientation of the forearm.     

Preference for human body odors is influenced by gender and sexual orientation

Human body odor may contribute to selection of partners. If so, sexual orientation may influence preference for and perhaps production of human body odors. In a test of these hypotheses, heterosexual and homosexual males and females made two-alternative forced-choice preference judgments for body odors obtained from other heterosexual and homosexual males and females. Subjects chose between odors from (a) heterosexual males and gay males, (b) heterosexual males and heterosexual females, (c) heterosexual females and lesbians, and (d) gay males and lesbians. Results indicate that differences in body odor are detected and responded to on the basis of, in part, an individual's gender and sexual orientation. Possible mechanisms underlying these findings are discussed.     

Independent resources for attentional tracking in the left and right visual hemifields

The ability to divide attention enables people to keep track of up to four independently moving objects. We now show that this tracking capacity is independently constrained in the left and right visual fields as if separate tracking systems were engaged, one in each field. Specifically, twice as many targets can be successfully tracked when they are divided between the left and right hemifields as when they are all presented within the same hemifield. This finding places broad constraints on the anatomy and mechanisms of attentive tracking, ruling out a single attentional focus, even one that moves quickly from target to target.     

How does attention select and track spatially extended objects? New effects of attentional concentration and amplification

Real-world situations involve attending to spatially extended objects, often under conditions of motion and high processing load. The present experiments investigated such processing by requiring observers to attentionally track a number of long, moving lines. Concurrently, observers responded to sporadic probes as a measure of the distribution of attention across the lines. The results revealed that attention is concentrated at the centers of lines during tracking, despite their uniformity, and that this center advantage grew as the lines became longer: Not only did observers get worse near the endpoints, but they became better at the lines' centers, as if attention became more concentrated as the objects became more extended. These results begin to show how attention is flexibly allocated in online visual processing to extended dynamic objects.     

Imitative learning of stimulus-response and response-outcome associations in pigeons

A novel automated procedure was used to study imitative learning in pigeons. In Experiments 1 and 2, observer pigeons witnessed a demonstrator pigeon successfully performing an instrumental discrimination in which different discriminative stimuli indicated which of 2 topographically distinct responses (R1 and R2) resulted in the delivery of seed. The observers were then presented with the discriminative stimuli and given access to the response panel. Observer pigeons' behavior during the discriminative stimuli was influenced by how the demonstrator had responded during these stimuli. In Experiment 3, observers witnessed demonstrator pigeons performing R1 for Outcome 1 and R2 for Outcome 2. Observers then received a procedure designed to devalue Outcome 1 relative to Outcome 2 and were subsequently less likely to perform R1 than R2. These results suggest that pigeons can learn both stimulus response and response-outcome associations by observation.     

What policymakers need and must demand from research regarding the employment rate of persons with disabilities

Enabling persons with disabilities to prepare for and engage in gainful employment has become a priority concern in U.S. society. As a result, federal and state policymakers are adopting employment-related initiatives designed to enhance the employment rate of persons with disabilities. Policymakers need credible evidence in order to assess and reform these initiatives. This recognized need, however, begs the question of what constitutes 'credible evidence.' Of particular concern in the disability policy arena is the debate over the types of conclusion about employment rates that can and cannot be drawn from analyses of national survey data sets. This article connects standard research methodology concepts with the complexities of evaluating disability policy to help stakeholders appreciate the issues involved in this debate. This appreciation can help policymakers (1) recognize unwarranted cause-and-effect conclusions based solely on existing national survey data and (2) demand better data and stronger research designs to complement the potential over-reliance on correlational studies using problematic survey data to estimate policy impacts. To this end, the article concludes with a practical framework with a checklist for assessing the adequacy of research regarding the employment rate of persons with disabilities.     

The Role of the Corpus Callosum in Interhemispheric Transfer of Information: Excitation or Inhibition?

The corpus callosum is the major neural pathway that connects homologous cortical areas of the two cerebral hemispheres. The nature of how that interhemispheric connection is manifested is the topic of this review; specifically, does the corpus callosum serve to communicate an inhibitory or excitatory influence on the contralateral hemisphere? Several studies take the position that the corpus callosum provides the pathway through which a hemisphere or cortical area can inhibit the other hemisphere or homologous cortical area in order to facilitate optimal functional capacity. Other studies suggest that the corpus callosum integrates information across cerebral hemispheres and thus serves an excitatory function in interhemispheric communication. This review examines these two contrasting theories of interhemispheric communication. Studies of callosotomies, callosal agenesis, language disorders, theories of lateralization and hemispheric asymmetry, and comparative research are critically considered. The available research, no matter how limited, primarily supports the notion that the corpus callosum serves a predominantly excitatory function. There is evidence, however, to support both theories and the possibility remains that the corpus callosum can serve both an inhibitory and excitatory influence on the contralateral hemisphere.