Delay discounting mediates the association between posterior insular cortex volume and social media addiction symptoms

Addiction-like symptoms in relation to excessive and compulsive social media use are common in the general population. Because they can lead to various adverse effects, there is a growing need to understand the brain systems and processes that are involved in potential social media addiction. We focus on the morphology of the posterior subdivision of the insular cortex (i.e., the insula), because it has been shown to be instrumental to supporting the maintenance of substance addictions and problematic behaviors. Assuming that social media addiction shares neural similarities with more established ones and consistent with evidence from the neuroeconomics domain, we further examine one possible reason for this association—namely that insular morphology influences one's delay discounting and that this delay discounting contributes to exaggerated preference for immediate social media rewards and consequent addiction-like symptoms. Based on voxel-based morphometry techniques applied to MRI scans of 32 social media users, we show that the gray matter volumes of the bilateral posterior insula are negatively associated with social media addiction symptoms. We further show that this association is mediated by delay discounting. This provides initial evidence that insular morphology can be associated with potential social media addiction, in part, through its contribution to poor foresight and impulsivity as captured by delay discounting.     

Category-length and category-strength effects using images of scenes

Global matching models have provided an important theoretical framework for recognition memory. Key predictions of this class of models are that (1) increasing the number of occurrences in a study list of some items affects the performance on other items (list-strength effect) and that (2) adding new items results in a deterioration of performance on the other items (list-length effect). Experimental confirmation of these predictions has been difficult, and the results have been inconsistent. A review of the existing literature, however, suggests that robust length and strength effects do occur when sufficiently similar hard-to-label items are used. In an effort to investigate this further, we had participants study lists containing one or more members of visual scene categories (bathrooms, beaches, etc.). Experiments 1 and 2 replicated and extended previous findings showing that the study of additional category members decreased accuracy, providing confirmation of the category-length effect. Experiment 3 showed that repeating some category members decreased the accuracy of nonrepeated members, providing evidence for a category-strength effect. Experiment 4 eliminated a potential challenge to these results. Taken together, these findings provide robust support for global matching models of recognition memory. The overall list lengths, the category sizes, and the number of repetitions used demonstrated that scene categories are well-suited to testing the fundamental assumptions of global matching models. These include (A) interference from memories for similar items and contexts, (B) nondestructive interference, and (C) that conjunctive information is made available through a matching operation.     

Capturing a More Complete View of Employees’ Lives Outside of Work: The Introduction and Development of New Interrole Conflict Constructs

This research introduces 4 new constructs that reflect interrole conflict (i.e., work‐to‐personal, personal‐to‐work, family‐to‐personal, and personal‐to‐family conflict) and provide a more complete view of the roles and responsibilities employees experience outside of work. An integration of interrole conflict literature and research on work and nonwork roles or domains highlights the importance of considering an individual's personal domain, which includes activities one pursues because of his or her own interests (e.g., friends, hobbies, community). Unfortunately, without conflict measures pertaining to this new role, researchers cannot clearly understand how roles other than family interfere with individuals’ work role including how interrole conflict impacts employees who do not have significant responsibilities in the family domain. Five phases of research across 4 separate samples were conducted in order to develop measures for the 4 new conflict constructs and to examine relationships with important work, family, life, and health outcomes. Findings from multisource data, including self‐rated, coworker‐rated, as well as single and nonsingle participants, show that the 4 new forms of interrole conflict have significant implications for employees and organizations.     

When death is not a problem: Regulating implicit negative affect under mortality salience

Terror management theory assumes that death arouses existential anxiety in humans which is suppressed in focal attention. Whereas most studies provide indirect evidence for negative affect under mortality salience by showing cultural worldview defenses and self‐esteem strivings, there is only little direct evidence for implicit negative affect under mortality salience. In the present study, we assume that this implicit affective reaction towards death depends on people's ability to self‐regulate negative affect as assessed by the personality dimension of action versus state orientation. Consistent with our expectations, action‐oriented participants judged artificial words to express less negative affect under mortality salience compared to control conditions whereas state‐oriented participants showed the reversed pattern.     

An Affordance-Based Approach to Visually Guided Overtaking

When an automobile driver overtakes a lead vehicle while avoiding oncoming traffic, does he or she do so with reference to the limits of his or her car? We investigated overtaking from the perspective of the theory of affordances. We define the overtake-ability affordance as a ratio of the minimum satisfying velocity required for safe overtaking (MSV) to the maximum velocity of the driver's car (V_max). Two groups of participants performed overtaking maneuvers, if deemed possible, by driving either a slow (V_max = 25 m/s) or a fast (V_max = 32.5 m/s) virtual car in overtaking situations constrained by 14 values of MSV. For any given MSV condition, participants in the fast car group were more likely to attempt an overtaking maneuver. However, when MSV was expressed in intrinsic units as a ratio of V_max for both groups, the frequency of overtaking was not significantly different across groups. Furthermore, overtaking frequency dropped to near 0% for both groups when MSV exceeded V_max. In accordance with the affordance-based framework (Fajen, 2007), our results suggest that participants select their overtaking maneuvers by perceiving an overtake-ability affordance.     

Values and helping behavior: A study in four cultures

Values are important factors in determining individuals' behaviours. Previous studies have examined the relations between values and helping behaviour, but usually in the context of a single culture. The current study examines the relations between personal value types and helping behaviour among university students (N = 722) in four cultures (Germany, Scotland‐UK, Israel and Turkey). Across cultures, the value types of self‐transcendence versus self‐enhancement and conservation versus openness to change were positively related to helping. Specifically, self‐transcendence values were positively related, and self‐enhancement and openness to change values negatively related, to helping behaviour. The correlations pattern did not differ significantly between cultures.     

Gaze avoidance in social phobia: Objective measure and correlates

Gaze aversion could be a central component of the physiopathology of social phobia. The emotions of the people interacting with a person with social phobia seem to model this gaze aversion. Our research consists of testing gaze aversion in subjects with social phobia compared to control subjects in different emotional faces of men and women using an eye tracker. Twenty-six subjects with DSM-IV social phobia were recruited. Twenty-four healthy subjects aged and sex-matched constituted the control group. We looked at the number of fixations and the dwell time in the eyes area on the pictures. The main findings of this research are: confirming a significantly lower amount of fixations and dwell time in patients with social phobia as a general mean and for the 6 basic emotions independently from gender; observing a significant correlation between the severity of the phobia and the degree of gaze avoidance. However, no difference in gaze avoidance according to subject/picture gender matching was observed. These findings confirm and extend some previous results, and suggest that eye avoidance is a robust marker of persons with social phobia, which could be used as a behavioral phenotype for brain imagery studies on this disorder.     

Continuum modeling of the reverse Hall–Petch effect in nanocrystalline metals under uniaxial tension: how many grains in a finite element model?

Owing to their very high strength, nanocrystalline metals have been extensively studied over the recent years. The direct Hall–Petch law, empirically proportioning the material strength to the inverse square root of its grain size has been shown to break down below a grain size of the order of tenths of nanometers. This phenomenon has been widely rationalized as a gradual switch from intragrain mediated deformation mechanisms to grain boundary mediated deformation mechanisms. This transition has been observed in many finite element simulations, despite the intrinsic restriction of necessarily limiting the nanocrystalline representative assembly to only a few grains. Such a limitation is generally overlooked, and its influence on an uniaxial tension test – when compared to a complete sample of millions of grains – ignored. We propose here to quantify the approximation done by considering a finite number of grains by means of a simple analytical model based on the early work of Stevens [R.N. Stevens, Philos. Mag. 23 (1971) p. 265]. The finite element approximation is demonstrated to be relatively good, even down to only three grains in width, and a method to “correct” the stress-strain curves of small representative volumes is proposed.