Genetically influenced change in sensation seeking drives the rise of delinquent behavior during adolescence

Sensation seeking is associated with an increased propensity for delinquency, and emerging research on personality change suggests that mean levels of sensation seeking increase substantially from childhood to adolescence. The current study tested whether individual differences in the rate of change of sensation seeking predicted within-person change in delinquent behavior and whether genetically influenced differences in rate of personality change accounted for this association. Sensation seeking and delinquent behavior were assessed biennially between ages 10-11 and 16-17 in a nationally representative sample of 7675 youths from the National Longitudinal Study of Youth: Children and Young Adults (CNLSY). Analyses using latent growth curve modeling found that within-person change in sensation seeking was significantly and positively correlated with within-person change in delinquency from childhood to adolescence. Furthermore, behavioral genetic analyses of a subset of 2562 sibling pairs indicated that there were substantial genetic influences on both initial levels of sensation seeking and change in sensation seeking during early adolescence, with over 80% of individual differences in change due to genetic factors. Finally, these genetically driven increases in sensation seeking were most important for predicting increases in delinquency, whereas environmental paths between sensation seeking and delinquency were not significant. These results suggest that developmental changes in delinquent behaviors during adolescence are driven by a genetically governed process of personality change.     

Barriers and facilitators to public bicycle scheme use: A qualitative approach

The purpose of this study was to explore barriers and facilitators to using CityCycle, a public bicycle share scheme in Brisbane, Australia. Focus groups were conducted with participants belonging to one of three categories. Group one consisted of infrequent and non-cyclists (no bicycle riding over the past month), group two were regular bicycle riders (ridden a bicycle at least once in the past month) and group three was composed of CityCycle members. A thematic analytic method was used to analyse the data. Three main themes were found: Accessibility/spontaneity, safety and weather/topography. The lengthy sign-up process was thought to stifle the spontaneity typically thought to attract people to public bike share. Mandatory helmet legislation was thought to reduce spontaneous use. Safety was a major concern for all groups and this included a perceived lack of suitable bicycle infrastructure, as well as regular riders describing a negative attitude of some car drivers. Interestingly, CityCycle riders unanimously perceived car driver attitudes to improve when on CityCycle bicycles relative to riding on personal bicycles. Conclusions: In order to increase the popularity of the CityCycle scheme, the results of this study suggest that a more accessible, spontaneous sign-up process is required, 24/7 opening hours, and greater incentives to sign up new members and casual users, as seeing people using CityCycle appears critical to further take up.     

Preschools reduce early academic-achievement gaps: a longitudinal twin approach

Preschools may reduce inequalities in early academic achievement by providing children from disadvantaged families with higher-quality learning environments than they would otherwise receive. In this study, longitudinal data from a nationally representative sample of more than 600 twin pairs were used to estimate the contributions of genes, the shared environment, and the nonshared environment to cognition and achievement scores in children enrolled versus not enrolled in preschool. Attending preschool at age 4 was associated with reductions in shared environmental influences on reading and math skills at age 5, but was not associated with the magnitude of shared environmental influences on cognition at age 2. These prospective effects were mediated by reductions in achievement gaps associated with minority status, socioeconomic status, and ratings of parental stimulation of cognitive development. Lower socioeconomic status was associated with lower rates of preschool enrollment, which suggests that the very children who would benefit most from preschools are the least likely to be enrolled in them.     

Remembering the best and worst of times: Memories for extreme outcomes bias risky decisions

When making decisions on the basis of past experiences, people must rely on their memories. Human memory has many well-known biases, including the tendency to better remember highly salient events. We propose an extreme-outcome rule, whereby this memory bias leads people to overweight the largest gains and largest losses, leading to more risk seeking for relative gains than for relative losses. To test this rule, in two experiments, people repeatedly chose between fixed and risky options, where the risky option led equiprobably to more or less than did the fixed option. As was predicted, people were more risk seeking for relative gains than for relative losses. In subsequent memory tests, people tended to recall the extreme outcome first and also judged the extreme outcome as having occurred more frequently. Across individuals, risk preferences in the risky-choice task correlated with these memory biases. This extreme-outcome rule presents a novel mechanism through which memory influences decision making.     

Visual regulation of manual aiming: A comparison of methods

Visual regulation of upper limb movements occurs throughout the trajectory and is not confined to discrete control in the target area. Early control is based on the dynamic relationship between the limb, the target, and the environment. Despite robust outcome differences between protocols involving visual manipulations, it remains difficult to identify the kinematic events that characterize these differences. In this study, participants performed manual aiming movements with and without vision. We compared several traditional approaches to movement analysis with two new methods of quantifying online limb regulation. As expected, participants undershot the target and their movement endpoints were more variable when vision was not available. Although traditional measures such as reaction time, time after peak velocity, and the presence of discontinuities in acceleration were sensitive to the visual manipulation, measures quantifying the trial-to-trial spatial variability throughout the trajectory were the most effective in isolating the time course of online regulation.     

The Influence of Walking Speed and Prior Practice on Locomotor Distance Estimation

In an attempt to reconcile discrepant findings in the literature (Elliott, 1986; Thomson, 1983), walking speed, prior practice, and walking delay were manipulated to determine if they had an impact on locomotor distance estimation. Contrary to suggestions by Thomson (1986), walking variability in the direction of locomotion depended only on a subject’s initial distance from the targets.     

Evidence that episodic memory impairment during tobacco abstinence is independent of attentional mechanisms

Previous studies have demonstrated reductions in episodic memory during nicotine withdrawal. However, these studies have been unable to dissociate memory reductions from losses in attention associated with tobacco abstinence. In the present study, the authors sought to determine whether episodic memory reduction is a primary effect of nicotine withdrawal during tobacco abstinence. Heavy smokers were tested when smoking normally and following 24 hrs of abstinence. Participants were tested with a recognition memory task in which items were studied under full and divided attention conditions. Forward digit span and backward digit span were also included as control measures. Withdrawal was associated with a reduction in memory performance that was independent of attention at encoding. The authors conclude that impairment of episodic memory is a primary effect of nicotine withdrawal during tobacco abstinence. Further research is required to determine if this is associated with continued use of tobacco and cessation failures.     

Approach and Avoidance Temperament as Basic Dimensions of Personality

ABSTRACT This research comprises 6 studies designed to examine approach and avoidance temperament as basic dimensions of personality. In Study 1, we developed direct measures of approach and avoidance temperament. In Study 2, we demonstrated that the approach and avoidance temperament variables are not epiphenomena of response biases. In Study 3, we documented the test‐retest stability of the temperament variables. In Study 4, we documented that approach and avoidance temperament are separate from other like‐valenced variables and may be construed as the core of these variables. In Study 5, we documented that approach and avoidance temperament are separate from chronic promotion and prevention foci. In Study 6, we distinguished the temperament variables from achievement goal variables and documented the temperament variables as antecedents of achievement goals and achievement goals as proximal predictors of performance. Approach and avoidance temperament are discussed as an ideal foundation for a strong, enduring structure of personality.