A unified account of categorical effects in phonetic perception

Categorical effects are found across speech sound categories, with the degree of these effects ranging from extremely strong categorical perception in consonants to nearly continuous perception in vowels. We show that both strong and weak categorical effects can be captured by a unified model. We treat speech perception as a statistical inference problem, assuming that listeners use their knowledge of categories as well as the acoustics of the signal to infer the intended productions of the speaker. Simulations show that the model provides close fits to empirical data, unifying past findings of categorical effects in consonants and vowels and capturing differences in the degree of categorical effects through a single parameter.     

Facebook's Contribution to Well-being among Adolescent and Young Adults as a Function of Mental Resilience

Studies of correlations between general internet use and psychological well-being have shown mixed results. The present study aimed to elucidate the relationship between Facebook use and psychological well-being, with mental resilience expected to moderate the relationship. Two hundred Israeli adolescents and young adults completed questionnaires assessing their Facebook use, mental resilience, and psychological well-being. Results showed that Facebook use was positively correlated with psychological well-being, and that this relationship was particularly strong for participants with low mental resilience. The findings support a positive effect of Facebook use as providing a virtual supportive community for individuals who may lack the social skills needed to develop social capital and confidence through traditional communication paths.     

Affective expressions in groups and inferences about members' relational well-being: The effects of socially engaging and disengaging emotions

Our findings draw attention to the interpersonal communication function of a relatively unexplored dimension of emotions—the level of social engagement versus disengagement. In four experiments, regardless of valence and target group gender, observers infer greater relational well-being (more cohesiveness and less conflict) between group members from socially engaging (sadness and appreciation) versus disengaging (anger and pride) emotion expressions. Supporting our argument that social (dis)engagement is a critical dimension communicated by these emotions, we demonstrate (1) that inferences about group members' self-interest mediate the effect of socially engaging emotions on cohesiveness and (2) that the influence of socially disengaging emotion expressions on inferences of conflict is attenuated when groups have collectivistic norms (i.e., members value a high level of social engagement). Furthermore, we show an important downstream consequence of these inferences of relational well-being: Groups that seem less cohesive because of their members' proud (versus appreciative) expressions are also expected to have worse task performance.     

Natural sequence of recovery from child post-traumatic amnesia: A retrospective cohort study

The aim of this study was to determine the sequence of skills recovery during post-traumatic amnesia (PTA) in children with moderate to severe traumatic brain injuries (TBIs). Setting: Fifty children aged 8 to 15 years consecutively admitted to a children’s hospital with TBI and PTA>24 were tested in a retrospective cohort study where the main measure was the Westmead PTA Scale (WPTAS). The group analyses show that orientation to time took longer to recover than orientation to person and place, but not memory, while the individual analyses revealed that when orientation to time was grouped with memory, 94% of children recovered orientation to person and place before orientation to time and memory (examiner and pictures). Correlation coefficients between age and the number of days taken to recover skills were not found to be significant. It was established that, in terms of the natural sequence of skills recovery in children aged 8 to 15 years following moderate to severe TBI, recovery of orientation to time is more closely aligned to memory than to orientation to person and place. It was also established that WPTAS items are developmentally appropriate for children aged 8 to 15 years who have sustained TBI. These findings are clinically important because monitoring recovery from PTA both impacts the rehabilitation offered to individuals during acute care and aids discharge planning.     

Inflected words in production: Evidence for a morphologically rich lexicon

Current evidence suggests that there is a difference between the representations of multimorphemic words in production and perception. In perception, it is widely believed that both whole-word and root representations exist, while in production there is little evidence for whole-word representations. The present investigation demonstrates that whole-word and root frequency independently predict the duration of words suffixed with –ing, –ed, and –s, which reveals that both root and word representations play a role in the production of inflected English words. In a second line of analysis, we find that the number of inflected phonological neighbours independently predicts the duration of monomorphemic words, which extends these results and suggests that whole-word representations exist at the lexical level. Together these results suggest that both root and word representations of inflected words are stored in the lexicon and are relevant for the production of both monomorphemic and multimorphemic words.     

Impaired Visuospatial Short-Term Memory in Children with ADHD

Previous studies provide clear evidence that visuospatial memory performance in children with attention-deficit/hyperactivity disorder (ADHD) is significantly lower than in typically developing children. In the present study, we investigated a major cause of their low performance using a spatial span test. Possibly, inattention resulting from lack of motivation or interest causes their low performance so that they do not correctly encode targets to be remembered. On the other hand, a deficit in temporary maintenance per se may cause their low performance; that is, their inefficient use of rehearsal during a retention interval may lead to memory traces’ fast decay. Results in this study indicated that children with ADHD could sustain attention during the encoding phase. Furthermore, their performance at delayed recall was significantly lower than immediate recall, but delayed recall did not affect typically developing children's performance. These results provide evidence for the likelihood that a factor causing children with ADHD difficulty in temporarily maintaining visuospatial information is fast decay of memory traces as a result of inefficient use of rehearsal, not inattention in the encoding phase.     

Power use and differential competence as determinants of subordinates' evaluative and behavioural responses in simulated organizations

Insights from leader–member exchange theory and social justice theory were combined to derive predictions about the effects of relative competence and power use by a more powerful other on evaluative and behavioural responses of subordinates. These predictions were tested in two experiments, using a simulated organizational structure. The main results of the first experiment (N=73) indicate that frequency of power use is an important determinant of subordinates' evaluations of the status quo, supporting predictions from leader–member exchange theory. However, in line with a procedural justice explanation, perceived legitimacy of the superior's behaviour and participants' cooperative intentions were determined jointly by power use and relative competence. A second experiment (N=152) more closely investigated behavioural responses. The findings obtained in Experiment 1 were replicated, and as predicted, interaction effects of the superior's power use and competence were found for subordinates' collaborative behaviour and employee turnover. Both these effects were mediated by participants' sense of commitment to their superior. Theoretical and practical implications of the findings are discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

Sex Differences in the Pathway from Low Birth Weight to Inattention/hyperactivity

Inattention/hyperactivity is a childhood outcome of low birth weight. However, the mechanisms by which low birth weight leads to inattention/hyperactivity are unclear. This study examined arousal, activation, motor speed, and motor coordination as possible mechanisms, attending to sex differences. 823 children (400 males) from Detroit and surrounding suburbs were assessed with the Child Behavior Checklist and the Teacher Report Form and completed experimental tasks to assess vigilance and activation (Continuous Performance Test signal detection parameters) and motor output speed and control (Grooved Pegboard) at 6 years of age. The relationship between birth weight and inattention/hyperactivity was slightly, but not significantly, stronger for boys than for girls. Arousal, motor speed, and motor coordination significantly partially mediated the relationship between birth weight and inattention/hyperactivity for boys and girls. Moderated mediation was found for the pathway between motor coordination and inattention/hyperactivity such that this relationship was stronger for boys than for girls. Sex differences in the associated features of attention symptoms may reflect partially distinct etiological pathways.     

Greater attention problems during childhood predict poorer executive functioning in late adolescence

Attention problems (behavior problems including inattention, disorganization, impulsivity, and hyperactivity) are widely thought to reflect deficits in executive functions (EFs). However, it is unclear whether attention problems differentially relate to distinct EFs and how developmental stability and change predict levels of EFs in late adolescence. We investigated, in an unselected sample, how teacher-rated attention problems from ages 7 to 14 years related to three correlated but separable EFs, measured as latent variables at age 17. Attention problems at all ages significantly predicted later levels of response inhibition and working memory updating, and to some extent set shifting; the relation to inhibiting was stronger than the relations to the other EFs or IQ. Growth models indicated that attention problems were quite stable in this age range, and it was the initial levels of problems, rather than their changes across time, that predicted later EFs. These results support the hypothesis that attention problems primarily reflect difficulties with response inhibition.