Do multielement visual tracking and visual search draw continuously on the same visual attention resources?

Multielement visual tracking and visual search are 2 tasks that are held to require visual-spatial attention. The authors used the attentional operating characteristic (AOC) method to determine whether both tasks draw continuously on the same attentional resource (i.e., whether the 2 tasks are mutually exclusive). The authors found that observers can search and track within the same trial significantly better than would be predicted if the 2 tasks were mutually exclusive. In fact, the AOC for tracking and search is similar to that for tracking and auditory monitoring. The results of additional experiments support an attention-switching account for this high level of dual-task performance in which a single attentional resource is efficiently switched between the tracking and search. The results provide important constraints for architectures of visual selective attention and the mechanisms of multielement tracking.     

Evidence for an activation locus of the word-frequency effect in lexical decision

The authors report a lexical decision experiment designed to determine whether activation is the locus of the word-frequency effect. K. R. Paap and L. S. Johansen (1994) reported that word frequency did not affect lexical decisions when exposure durations were brief; they accounted for this by proposing that data-limited conditions prevented late-occurring verification processes. Subsequently, P. A. Allen, A. F. Smith, M. Lien, T. A. Weber, and D. J. Madden (1997) and K. R. Paap, L. S. Johansen, E. Chun, and P. Vonnahme (2000) reported additional evidence that word-frequency effects do and do not have an activation locus, respectively. The authors further tested this issue in a lexical decision experiment using data-limited procedures--predicted by verification models to eliminate word-frequency effects. The authors observed word-frequency effects using individually determined exposure durations that were only 1 screen cycle longer than the exposure duration that yielded chance performance. Word-frequency effects persisted even when an adjusted measure of performance was used.     

Understanding the social costs of narcissism: the case of the tragedy of the commons

Two studies examined narcissism and behavior in a commons dilemma. Study 1 used a four-person, laboratory-based task and Study 2 used a dyadic task. Participants were told that they represented one of four (Study 1) or two (Study 2) forestry companies and then were asked to harvest timber from a renewable forest. Narcissism was found to be positively related to acquisitive goals and harvesting more timber in the initial round. The more narcissists harvesting in the competitive group of four (Study 1) or dyad (Study 2), the less timber was harvested overall and the more rapidly the forest was depleted. Within competitive groups and dyads, however, narcissists harvested more than the nonnarcissists competing with them. In all, narcissism provided a benefit to the self, but at a long-term cost to other individuals and to the commons.     

The emerging fragile X premutation phenotype: evidence from the domain of social cognition

Fragile X syndrome is a neurodevelopmental disorder that is caused by large methylated expansions of a CGG repeat (>200) region upstream of the FMR1 gene that results in the lack of expression of the fragile X mental retardation protein (FMRP). Affected individuals display a neurobehavioral phenotype that includes a significant impairment in social cognition alongside deficits in attentional control, inhibition and working memory. In contrast, relatively little is known about the trajectory and specificity of any cognitive impairment associated with the fragile X premutation ("carrier-status") (approximately 55-200 repeats). Here, we focus on one aspect of cognition that has been well documented in the fragile X full mutation, namely social cognition. The results suggest that premutation males display a pattern of deficit similar in profile, albeit milder in presentation, to that of the full mutation. However, little evidence emerged for a correlation between CGG repeat length and severity of phenotypic outcomes. The findings are discussed in the context of functional neuroimaging and brain-behaviour-molecular correlates. We speculate that the deficiencies in social cognition are attributable to impairment of neural pathways modulated by the cerebellum.     

Cerebrospinal fluid concentrations of biogenic amines and corticotropin-releasing factor in adolescent non-human primates as a function of the timing of adverse early rearing

Adolescent bonnet macaques nursed as infants by mothers facing unpredictable requirements for food procurement (variable foraging demand, VFD) display persistent neurobiological disturbances. This study examined the long-term neurochemical and behavioral effects of adverse rearing initiated later in infancy than in previous cohorts of subjects to test the hypothesis that the timing of an early adverse experience would influence patterns of biobehavioral outcome. Cisternal cerebrospinal fluid (CSF) monoamine and corticotropin-releasing factor (CRF) concentrations were obtained from 20 bonnet macaques (11 VFD-reared and 9 normally reared controls) approximately 2 years after the end of differential rearing. VFD-reared primates displayed on multiple samplings significantly lower CSF CRF concentrations and higher CSF 5-hydroxyindoleacetic acid (5-HIAA) concentration compared to controls. In the VFD-reared, significant inverse correlations between CRF and all three monoamines were found (5-HIAA, 3-methoxy-4-hydroxyphenethyleneglycol and homovanillic acid), most prominently for 5-HIAA. In controls, but not VFD-reared subjects, CSF CRF was positively correlated with changes in "gregariousness" upon presentation of a fear stimulus. VFD-reared subjects displayed greater baseline hierarchical engagement than controls. In contrast to prior findings, in which rearing under VFD conditions at an earlier age led to increased CSF CRF compared with controls, CSF CRF was lower after later exposure to VFD rearing than in controls. Thus, the timing of exposure to VFD conditions early in life evidently determines whether CSF CRF was found to be elevated or decreased, within the context of increased serotonin metabolism, during the course of primate maturation.     

Personality predicts working-memory-related activation in the caudal anterior cingulate cortex

Behavioral studies suggest that two affective dimensions of personality are associated with working memory (WM) function. WM load is known to modulate neural activity in the caudal anterior cingulate cortex (ACC), a brain region critical for the cognitive control of behavior. On this basis, we hypothesized that neural activity in the caudal ACC during a WM task should be associated with personality: correlated negatively with behavioral approach sensitivity (BAS) and positively with behavioral inhibition sensitivity (BIS). Using functional magnetic resonance imaging, we measured brain activity in 14 participants performing a three-back WM task. Higher self-reported BAS predicted better WM performance (r = .27) and lower WM-related activation in the caudal ACC (r = -.84), suggesting personality differences in cognitive control. The data bolster approach-withdrawal (action control) theories of personality and suggest refinements to the dominant views of ACC and personality.     

Inadequate Housing Among Families Under Investigation for Child Abuse and Neglect: Prevalence from a National Probability Sample

This study aimed to estimate the prevalence of inadequate housing that threaten out-of-home placement among families under investigation by child welfare. Data came from the National Survey of Child and Adolescent Well-Being, a nationally representative longitudinal survey of child welfare-involved families. Child protective services caseworkers as well as caregivers provided information on families whose child remained in the home after initial investigation (N = 3,867). Multilevel latent class analyses tested the presence of inadequately housed subgroups using 4 housing problem indicators at baseline. Logistic regressions assessed convergent and predictive validity. A two class latent solution best fit the data. Findings indicated that inadequate housing contributed to risk for out-of-home placement in approximately 16 % of intact families under investigation by child protective services. These families were 4 times more likely to need housing services 12 months later. Federal legislation emphasizes integration of social services as necessary to end homelessness. This study demonstrates overlap across public agencies. Enhanced coordination of child welfare and housing services facilitates interventions to prevent and mitigate homelessness.     

Asymmetrical loading affects intersegmental dynamics during the swing phase of walking

Much of the work related to lower extremity inertia manipulations has focused on temporal, kinematic and traditional inverse dynamics assessments during locomotion. Intersegmental dynamics is an analytical technique that provides further insights into mechanisms underlying linked-segment motion. The purpose of this study was to determine how intersegmental dynamics during the swing phase of walking are altered during asymmetrical lower extremity loading. Participants walked overground at a speed of 1.57 m s^?1 with 0, 0.5, 1.0, and 2.0 kg attached to one foot. Net, interaction, gravitational, and muscle moments were computed. Moment magnitudes at joints of the loaded leg increased systematically with increasing load, whereas unloaded leg moments were unaffected by loading. With increasing load, relative contributions of interaction moments about the knee and hip and gravitational moment about the ankle increased (i.e., 21%, 8%, and 44% increases, respectively), whereas the relative contributions of muscle moments about all three joints declined (i.e., ?4%, ?13%, and ?8% decreases for the ankle, knee, and hip, respectively for unloaded vs. 2.0 kg). These results suggest that altered inertia properties of the limb not only affected the amount of muscular effort required to swing the leg, but also changed the nature of the interaction between segments.