Functional Impulsivity as a Psychometric Manifestation of the Behaviour Activation System: a Contribution to the Solution of the 'Impulsivity Problem'.

The Reinforcement Sensitivity Theory (RST) view of personality has for many years related impulsivity to the Behaviour Activation System (BAS), a neurobiological network mediating appetitively motivated approach of reward. The wider literature however suggests that there are many varied manifestations of impulsivity, and it is not clear how these traits are to be reconciled with - or distinguished from - RST. Dickman (1990) has suggested that there are two principal forms of impulsivity; 1) dysfunctional impulsivity, which captures the traditionally negative view of this trait as failing to 'look before you leap', which seems unrelated to the RST view; and 2) functional impulsivity, which reflects the potential benefits of acting quickly, and which we argue is theoretically consistent with proposed manifestations of the BAS. In our first study, we investigate the relationship that Dickman's impulsivity scales have with measures of both RST and personality in general. We concluded that functional impulsivity may provide a useful psychometric measure of BAS, whereas dysfunctional impulsivity seems unrelated to RST. In our second study we use a go/no-go paradigm to confirm our conclusions empirically. Results indicated that functional impulsivity, along with two purpose-built BAS measures from the literature, was a significant predictor of increased responding to reward. In comparison, dysfunctional impulsivity predicted increased responding irrespective of whether responses were rewarded or punished. We discuss the significance of our findings to RST specifically, and personality research overall, concluding that this research compliments but theoretically refines Dickman's (1990) dichotomization of impulsivity

Dimension of the Torelli group for Out(F_n)

Let T_n be the kernel of the natural map from Out(F_n) to GL(n,Z). We use combinatorial Morse theory to prove that T_n has an Eilenberg-MacLane space which is (2n-4)-dimensional and that H_{2n-4}(T_n,Z) is not finitely generated (n at least 3). In particular, this recovers the result of Krstic-McCool that T_3 is not finitely presented. We also give a new proof of the fact, due to Magnus, that T_n is finitely generated.Comment: 27 pages, 9 figure

Individual differences in good manners rather than compassion predict fair allocations of wealth in the dictator game

Objective. One of the most common tools for studying prosociality is the dictator game, in which allocations to one’s partner are often described in terms of altruism. However, there is less consensus regarding the motivations driving these allocations, which may represent either emotional concern for others (compassion), adherence to social norms regarding fairness (politeness), or both. Method. In this paper, we apply personality psychology to the study of behavior in the dictator game, in which we examine the discriminant validity of distinct prosocial constructs from the Big Five and HEXACO models in relation to allocations of wealth. Results. Across four studies (combined N = 798) utilizing both hypothetical and incentivized designs, we found that the politeness—but not compassion—aspect of Big Five agreeableness, as well as HEXACO honesty-humility, uniquely predicted dictator allocations within their respective personality models. Conclusions. These findings contribute to a growing literature indicating that the standard dictator game measures “good manners” or adherence to norms concerning fairness, rather than pure emotional concern or compassionate motives, which have important implications for how this paradigm is used and interpreted in psychological research

Personality Measures Link Slower Binocular Rivalry Switch Rates to Higher Levels of Self-Discipline

In this paper we investigated the relation between personality and the rate of perceptual alternations during binocular rivalry. Studies have demonstrated that slower rivalry alternations are associated with a range of clinical conditions. It is less clear whether rivalry dynamics similarly co-vary with individual differences in psychological traits seen across non-clinical population. We assessed rivalry rates in a non-clinical population (n = 149) and found slower rivalry alternations were positively related r(149) = 0.20, p = 0.01 to industriousness, a trait characterized by a high level of self-discipline using the Big Five Aspect Scales (BFAS). Switch rates were also negatively related r(149) = -0.20, p = 0.01 to cognitive disorganization, a schizotypy trait capturing schizophrenia-like symptoms of disorganization using the Oxford-Liverpool Inventory of feelings and Experiences (O-LIFE). Furthermore, we showed that that these relations with personality were unaffected by the inclusion or exclusion of mixed percept in the response analysis. Together these results are relevant to theoretical models of rivalry investigating individual differences in rivalry temporal dynamics and they may reduce concerns about the impact of task compliance in clinical research using rivalry as a potential diagnostic tool

On the shoulders of giants

British psychologists such as Hans Eysenck and Jeffrey Gray have been giants in the field of individual differences, offering psychobiological accounts of major personality traits such as extraversion and neuroticism, as well as the cluster of impulsive antisocial sensation-seeking personality facets, marked by Eysenck's psychoticism scale. These theories have stimulated vibrant research programmes worldwide, including several within British psychology departments. This article provides a snapshot of classic and contemporary British research into the affective, behavioural and cognitive processes which characterise personality

Extraversion and Reward-Processing: Consolidating Evidence from an Electroencephalographic Index of Reward-Prediction-Error

Trait extraversion has been theorized to emerge from functioning of the dopaminergic reward system. Recent evidence for this view shows that extraversion modulates the scalp-recorded Reward Positivity, a putative marker of dopaminergic signaling of reward-prediction-error. We attempt to replicate this association amid several improvements on previous studies in this area, including an adequately-powered sample (N = 100) and thorough examination of convergent-divergent validity. Participants completed a passive associative learning task presenting rewards and non-rewards that were either predictable or unexpected. Frequentist and Bayesian analyses confirmed that the scalp recorded Reward Positivity (i.e. the Feedback-Related-Negativity contrasting unpredicted rewards and unpredicted non-rewards) was significantly associated with three measures of extraversion and unrelated to other basic traits from the Big Five personality model. Narrower sub-traits of extraversion showed similar, though weaker associations with the Reward Positivity. These findings consolidate previous evidence linking extraversion with a putative marker of dopaminergic reward-processing

Polynomial diffeomorphisms of C^2, IV: The measure of maximal entropy and laminar currents

This paper concerns the dynamics of polynomial automorphisms of ${\bf C}^2$. One can associate to such an automorphism two currents $\mu^\pm$ and the equilibrium measure $\mu=\mu^+\wedge\mu^-$. In this paper we study some geometric and dynamical properties of these objects. First, we characterize $\mu$ as the unique measure of maximal entropy. Then we show that the measure $\mu$ has a local product structure and that the currents $\mu^\pm$ have a laminar structure. This allows us to deduce information about periodic points and heteroclinic intersections. For example, we prove that the support of $\mu$ coincides with the closure of the set of saddle points. The methods used combine the pluripotential theory with the theory of non-uniformly hyperbolic dynamical systems

The Vasoactive Potential of Kisspeptin-10 in the Peripheral Vasculature

Splice products of the Kiss1 protein (kisspeptins) have been shown to be involved in a diverse range of functions, including puberty, metastasis and vasoconstriction in large human arteries. Circulating Kisspeptin-10 (Kp-10) plasma levels are low in normal individuals but are elevated during various disease states as well as pregnancy. Here, we investigated the potential of Kp-10, the shortest biologically active kisspeptin, to influence microvascular effects, concentrating on the cutaneous vasculature. Kp-10 caused a dose-dependent increase in oedema formation (0.3–10nmol/injection site), assessed by Evans Blue albumin dye extravasation, in the dorsal skin of CD1 mice. Oedema formation was shown to be inhibited by the histamine H1 receptor antagonist mepyramine. The response was characterised by a ring of pallor at the injection site in keeping with vasoconstrictor activity. Therefore, changes in dorsal skin blood flow were assessed by clearance of intradermally injected 99mtechnetium. Kp-10 was found to significantly reduce clearance, in keeping with decreased blood flow and providing further evidence for vasoconstrictor activity. The decreased clearance was partially inhibited by co-treatment with the cyclo-oxygenase inhibitor indomethacin. Finally evidence for the kisspeptin receptor gene (Kiss1R), but not the kisspeptin peptide gene (Kiss1), mRNA expression was observed in heart, aorta and kidney samples from normal and angiotensin II induced hypertensive mice, with similar mRNA levels observed in each. We have evidence for two peripheral vasoactive roles for kisspeptin-10. Firstly, plasma extravasation indicative of ability to induce oedema formation and secondly decreased peripheral blood flow, indicating microvascular constriction. Thus Kp-10 has vasoactive properties in the peripheral microvasculature