Lower limb kinematic variability in dancers performing drop landings onto floor surfaces with varied mechanical properties

Elite dancers perform highly skilled and consistent movements. These movements require effective regulation of the intrinsic and extrinsic forces acting within and on the body. Customized, compliant floors typically used in dance are assumed to enhance dance performance and reduce injury risk by dampening ground reaction forces during tasks such as landings. As floor compliance can affect the extrinsic forces applied to the body, secondary effects of floor properties may be observed in the movement consistency or kinematic variability exhibited during dance performance. The aim of this study was to investigate the effects of floor mechanical properties on lower extremity kinematic variability in dancers performing landing tasks. A vector coding technique was used to analyze sagittal plane knee and ankle joint kinematic variability, in a cohort of 12 pre-professional dancers, through discrete phases of drop landings from a height of 0.2 m. No effect on kinematic variability was observed between floors, indicating that dancers could accommodate the changing extrinsic floor conditions. Future research may consider repeat analysis under more dynamic task constraints with a less experienced cohort. However, knee/ankle joint kinematic variability was observed to increase late in the landing phase which was predominantly comprised of knee flexion coupled with the terminal range of ankle dorsiflexion. These findings may be the result of greater neural input late in the landing phase as opposed to the suggested passive mechanical interaction of the foot and ankle complex at initial contact with a floor. Analysis of joint coordination in discrete movement phases may be of benefit in identifying intrinsic sources of variability in dynamic tasks that involve multiple movement phases.     

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.     

Dispositional accounts of evil personhood

It is intuitively plausible that not every evildoer is an evil person. In order to make sense of this intuition we need to construct an account of evil personhood in addition to an account of evil action. Some philosophers have offered aggregative accounts of evil personhood, but these do not fit well with common intuitions about the explanatory power of evil personhood, the possibility of moral reform, and the relationship between evil and luck. In contrast, a dispositional account of evil personhood can allow that evil is explanatory, that an evil person can become good, and that luck might prevent evil persons from doing evil or cause non-evil persons to do evil. Yet the dispositional account of evil personhood implies that some evil persons are blameless, which seems to clash with the intuition that evil persons deserve our strongest moral condemnation. Moreover, since it is likely that a large proportion of us are disposed to perform evil actions in some environments, the dispositional account threatens to label a large proportion of people evil. In this paper I consider a range of possible modifications to the dispositional account that might bring it more closely into alignment with our intuitions about moral condemnation and the rarity of evil persons. According to the most plausible of these theories, S is an evil person if S is strongly disposed to perform evil actions when in conditions that favour S’s autonomy.     

Gender Differences in the ABC’s of the Birds and the Bees: What Mothers Teach Young Children About Sexuality and Reproduction

Sexuality education is heavily gendered at adolescence. This study uses data from a national web survey of 631 U.S. mothers of 3 to 6 year old children to test whether similar gender differences exist in what mothers teach their young children about sexuality and reproduction. We test (a) whether mothers will report talking more with daughters or sons about sexuality related issues, and (b) whether mothers will report greater comfort talking about such issues with daughters or sons. We find (a) that mothers talk more to daughters than sons about romantic relationships, reproductive bodies, and morality, but not about sexual abuse or intercourse/pleasure. We find (b) mixed results regarding mothers’ comfort in talking with daughters or sons about sexuality.     

Clarifying the Relation Between Extraversion and Positive Affect

This article clarifies two sources of ambiguity surrounding the relation between extraversion and positive affect. First, positive affect is defined differently across major models of the structure of affect. Second, no previous research has examined potentially diverging associations of lower‐order aspects of extraversion (i.e., assertiveness and enthusiasm) with positive affect. Australian (Study 1: N = 437, 78% female, M_age = 20.41) and American (Study 2: N = 262, 39% female, M_age = 33.86) participants completed multiple measures of extraversion and positive affect. Correlations were employed to examine relations among these measures. In both studies, extraversion was most clearly associated with positive affect as conceptualized within a major factor model of affect—specifically, as positive activation (Watson & Tellegen, 1985)—rather than the valence‐based conceptualization of positive affect provided by a circumplex model of affect (Russell, 1980). This was also the case for the assertiveness and enthusiasm aspects of extraversion. Our findings clarify the nature of the positive affective component of extraversion, which is best described in terms of both positive valence and high activation.