Thermal behaviour of polystyrene/silica composites

The particle-size distribution in silica powder prepared by the sol–gel method has been determined by dynamic light scattering analysis. The average diameter of the particles was found to be 250?nm. Using a low-temperature nitrogen adsorption–desorption technique, it was found that the synthesised powder may be referred to as mesoporous materials. Polystyrene/silica composite films were fabricated by casting from o-xylene solutions. It was found, using thermogravimetry, that incorporation of silica leads to an increase in both the onset temperature of polymer degradation and in the temperature at which the maximum rate of weight loss occurs. Using differential scanning calorimetry, the phase transitions from the glassy state to the elastic one were studied for the polymeric materials. New data relating to the effect of silica on the glass-transition temperature, T_g, of composites with a low weight fraction of SiO₂ were found. Specifically, we found a non-monotonic concentration dependence of the value of T_g. The present results advocate for employing silica as an effective filler for producing polymer composites with enhanced thermal properties.     

Learning to Decide with and without Reasoning: How Task Experience Affects Attribute Weighting and Preference Stability

Certain experiments have shown that reasoning may weaken the stability of people's preferences, especially with regard to well‐learned perceptual judgment and decision‐making tasks, while learning has an opposite, consistency‐enhancing effect on preferences. We examined the effects of these factors in a visual multi‐attribute decision‐making task where reasoning, in contrast, has been found to benefit judgments by making them more stable. The initial assumption in this study was that this benefit would be typical for novel tasks, like the one employed here, and that it would decrease when the task is thoroughly learned. This assumption was examined in three experiments by contrasting it with an alternative assumption that this previously obtained beneficial effect is caused solely by learning, not by reasoning. It was found that learning indeed makes preferences more stable by consolidating the weights of the attributes. Reasoning, however, does not benefit this task when it is completely novel but facilitates learning and stability of the preferences long run, therefore increasing the consistency of the participants in the macrolevel. Copyright © 2017 John Wiley & Sons, Ltd.     

Stability and Change in Domain‐specific Self‐esteem and Global Self‐esteem

A notable uptick of interest in the stability of self‐esteem has been observed over the past few years. Most researchers, however, have focused on unidimensional rather than multidimensional conceptualizations of self‐esteem. The paucity of empirical research is surprising given conflicting theoretical perspectives on the stability of self‐esteem. The goal of the present study was to thoroughly disentangle different conceptualizations of self‐esteem and test opposing classical theories on (i) the stability and (ii) the direction of mutual influence of these different forms of self‐esteem. We analysed two‐year longitudinal data from participants (N = 644 at T1, N = 241 at T2) with an average age of 47.0 years (SD = 12.4). Analyses using a latent variable approach revealed that the domains of self‐esteem were relatively stable in terms of rank order and mean levels. In fact, the size of the stability coefficients was comparable to that of other trait measures that have been reported in the literature and paralleled the stability observed for global self‐esteem. Results did not provide support for either top‐down or bottom‐up effects between domain‐specific and global self‐esteem. These findings have important theoretical and practical implications regarding the stability and development of self‐esteem in adulthood and advance the understanding of self‐esteem in personality theory. © 2018 European Association of Personality Psychology     

The stability and causal effects of task‐specific and generalized self‐efficacy in college1

This research investigated the stability and causal effects of task‐specific self‐efficacy and generalized self‐efficacy in college students. In Study 1, task‐specific self‐efficacy and generalized self‐efficacy scales were administered to university students (N = 237) on two occasions, with an interval of 2 months. In Study 2, task‐specific (care‐work) self‐efficacy and generalized self‐efficacy scales were administered to college students who were studying to be care workers (N = 49) on three occasions (before the first care‐work practicum, after the practicum, and 3 months later). The results of both studies indicated that generalized self‐efficacy was more stable than task‐specific self‐efficacy. In Study 1, both generalized self‐efficacy and task‐specific self‐efficacy affected each other in daily life. Study 2 examined the effects of an ego‐engaged experience (the first care‐work practicum) for task‐specific (care‐work) self‐efficacy and generalized self‐efficacy. The results indicated that changes in care‐work self‐efficacy did not affect generalized self‐efficacy.     

Attention Is Required to Coordinate Reaching and Postural Stability during Upper Limb Movements Generated While Standing

Abstract

In the present study we investigated how attention contributes to the interaction between reach planning and execution, and postural control. Reaching movements were generated while standing and were performed either in isolation or in conjunction with a secondary reaction time (RT) task. In addition, to better understand how online movement control is affected by this interaction, the reaching movements could be unexpectedly perturbed medial-laterally. Postural kinetic, arm kinematic and RT, and secondary RT measures were used to characterize the responses. Results indicate task performance worsened when both the reaching and secondary tasks were completed simultaneously. Our results imply the generation of reaching movements while standing requires attentional resources to properly coordinate the interaction between the reaching task and postural control.     

Stability,Change, and Informant Variance in Newlyweds' Physical Aggression: Individual and Dyadic Processes

Individual and dyadic stability models of newlyweds' physical aggression were evaluated in a sample of 394 newlywed community couples recruited at engagement and followed for 2.5 years. Aggression in young couples was hypothesized to be a stable, enduring trait, consistent with a latent state–trait conceptualization. However, the findings indicated that aggression can more parsimoniously be conceptualized as a “somewhat stable” trait with strong short‐term correlations that gradually decrease at increasing intervals. Aggression was significantly dyadic. Men and women's aggression were consistently associated with one another across time beginning at engagement, with little evidence that one person's aggression evoked aggression in the partner in the time intervals studied. Consistency in a person's reporting of aggression, not shared with the partner, was strongest for self‐reports. Aggr. Behav. 38:1‐15, 2012. © 2011 Wiley Periodicals, Inc.     

Why More Intelligent Individuals Like Classical Music

The origin of values and preferences is an unresolved theoretical problem in social and behavioral sciences. The Savanna‐IQ Interaction Hypothesis, derived from the Savanna Principle and a theory of the evolution of general intelligence, suggests that more intelligent individuals are more likely to acquire and espouse evolutionarily novel values and preferences than less intelligent individuals but that general intelligence has no effect on the acquisition and espousal of evolutionarily familiar values and preferences. Recent work on the evolution of music suggests that music in its evolutionary origin was always vocal and that purely instrumental music is evolutionarily novel. The Savanna‐IQ Interaction Hypothesis would then imply that more intelligent individuals are more likely to prefer purely instrumental music than less intelligent individuals, but general intelligence has no effect on the preference for vocal music. The analyses of American (General Social Surveys) and British (British Cohort Study) data are consistent with this hypothesis. Additional analyses suggest that the effect of intelligence on musical preference is not a function of the cognitive complexity of music. Copyright © 2011 John Wiley & Sons, Ltd.     

Temporal stability of behavioural intention as a moderator of intention–health behaviour relationships

Seven prospective studies of health behaviours containing eight prospective datasets testing the moderating role of intention stability on intention–behaviour and past behaviour–behaviour relationships were examined within the context of the Theory of Planned Behaviour. The measure of intention stability was based on lack of change in intentions between the two measurement time points. Across different behaviours, samples and time frames more stable intentions were associated with intentions at time 1 that were stronger predictors of behaviour at time 2. Intention stability did not consistently moderate the past behaviour–behaviour relationship. Across studies the frequency-weighted mean correlation between intentions and behaviour was substantially greater for stable (r ₊?=?0.60) compared to unstable (r ₊?=?0.27) intentions (Z _difference?=?6.65, p?<?0.001). The past behaviour–behaviour correlation was also stronger for stable (r ₊?=?0.50, p?<?0.001) compared to unstable (r₊ ?=?0.34, p?<?0.001) intentions (Z _difference?=?3.12, p?<?0.01). Perceived behavioural control was the variable most strongly related to stable intentions. Implications for understanding the role of health cognitions in the performance of health behaviour are discussed.     

The use of implementation intentions and the decision balance sheet in promoting exercise behaviour

Although increasing exercise and fitness has often been associated with positive health outcomes, infrequent exercise participation has remained a problem. Since two distinct motivational and volitional phases to goal pursuit have been proposed, a combined motivational (decision balance sheet, DBS) and volitional (implementation intentions) intervention was predicted to be more effective in increasing exercise behaviour than a control or either strategy alone. A total of 86 students were randomly assigned to one of the four conditions, and were all asked to try to exercise two more times a week than they currently did, over a four week period. Their fitness levels were measured through fitness tests conducted pre- and post-intervention. A priori orthogonal contrasts indicated that the experimental strategies produced a greater increase in exercise frequency and total time spent exercising per week and accordingly showed greater fitness improvements than the control group. Moreover, the volitional groups taken together produced greater increase in time spent exercising and a marginally greater improvement in frequency than the DBS alone. The combined intervention led to improvements in fitness and marginal increases in frequency over the implementation intention alone group. It is proposed that for the combined group the DBS may have aided recall of the implementation intention or increased commitment to it, as remembering and then acting on the plan, in the stated place and time, mediated the implementation intention–behaviour relationship. The combined intervention produced the greatest fitness improvements, indicating that this strategy can lead to important health benefits.     

A comparison of working memory profiles in children with ADHD and DCD

The main objective of present study was to investigate whether the patterns of working memory performance differ as a function of attention and motor difficulties, and whether children with ADHD and DCD could be reliably discriminated on the basis of their memory deficits. A related aim was to investigate the link between their working memory profiles and academic attainment. Fifty children with ADHD-Combined, 55 children with DCD, and an age-matched group of 50 typically developing children with average working memory were assessed on standardized measures of working memory, IQ, and academic attainment (reading, spelling, comprehension, and math). The normal controls performed significantly better than both clinical groups on all working memory tests. Specific patterns emerged in the memory profile of the clinical groups: The children with DCD had a depressed performance in all working memory tests, with particularly low scores in visuospatial memory tasks; children with ADHD performed within age-expected levels in short-term memory but had a pervasive working memory deficit that impacted both verbal and visuospatial domains. The clinical groups could reliably be discriminated on the basis of their short-term memory scores. Their learning profiles were similar. It is possible that the working memory profiles of the children with ADHD and DCD are influenced by distinct underlying cognitive mechanisms, rather than a general neurodevelopmental delay. Despite these distinctive patterns of memory performance, both clinical groups performed similarly on academic attainments, suggesting that memory may underlie learning difficulties, independent of related clinical disorders.