Brain dynamics of word familiarization in 20-month-olds: effects of productive vocabulary size

The present study investigated the brain mechanisms involved during young children's receptive familiarization with new words, and whether the dynamics of these mechanisms are related to the child's productive vocabulary size. To this end, we recorded event-related potentials (ERPs) from 20-month-old children in a pseudoword repetition task. Results revealed distinct patterns of repetition effects for children with large and small productive vocabularies. High producers showed evidence of recognizing the novel words already after three presentations, while the low producers needed five presentations to display a recognition effect. The familiarization process was manifested in the modulations of two components, the N200-400 and a later fronto-central component, which appeared to increase in amplitude until a certain level of encoding was reached and then decrease with further repetition. These findings suggest a relation between the onset of the productive vocabulary spurt and the rate of receptive word familiarization.     

Left gaze bias in humans, rhesus monkeys and domestic dogs

While viewing faces, human adults often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee’s face is often inspected first and for longer periods. Using a preferential looking paradigm, we demonstrate that this bias is neither uniquely human nor limited to primates, and provide evidence to help elucidate its biological function within a broader social cognitive framework. We observed that 6-month-old infants showed a wider tendency for left gaze preference towards objects and faces of different species and orientation, while in adults the bias appears only towards upright human faces. Rhesus monkeys showed a left gaze bias towards upright human and monkey faces, but not towards inverted faces. Domestic dogs, however, only demonstrated a left gaze bias towards human faces, but not towards monkey or dog faces, nor to inanimate object images. Our findings suggest that face- and species-sensitive gaze asymmetry is more widespread in the animal kingdom than previously recognised, is not constrained by attentional or scanning bias, and could be shaped by experience to develop adaptive behavioural significance.     

Is Retirement Good or Bad for Subjective Well-Being?

Retirement has been viewed either as a transition that is accompanied by psychological distress or as a time of continued, or even enhanced, subjective well-being. Existing evidence is mixed, with some studies reporting retirement as positively related to well-being and others reporting a negative relationship or none at all. Our research indicates that developmental and social contexts shape an individual’s retirement decisions and experiences, so that retirement should be studied in its ecological and life-course context. Research on marital quality and subjective well-being in retirement has demonstrated both similarities and differences between men and women, as well as the need to consider couples conjointly (rather than viewing individuals in isolation). Future research focusing on the retirement process as it unfolds over time and in ecological context can serve to illuminate the circumstances under which retirement promotes or detracts from the quality of life.     

Parent characteristics and parent-child interactions in families of nonproblem children and ADHD children with higher and lower levels of oppositional-defiant behavior

This study examined parent-child interactions and parent characteristics in families of nonproblem children and attention deficit hyperactivity disorder (ADHD) children with lower (ADHD-LOD) and higher (ADHD-HOD) levels of oppositional-defiant behavior. Families of ADHD children were recruited from a parent training program. Observed and parent-reported child behavior problems were highest in the ADHD-HOD group. Observed parent behavior revealed few differences, but daily reports indicated that parents in both ADHD groups used more negative-reactive and fewer positive parenting strategies than control parents. Maternal psychological functioning differed between the ADHD and nonproblem groups, but not between the two ADHD groups. Fathers of ADHD-HOD children reported more psychological disturbance than controls. Parenting self-esteem was lowest in the ADHD-HOD group and highest in the nonproblem group. The results support the LOD and HOD distinction, but also suggest that, although certain difficulties are more common in the families of ADHD-HOD children, families of ADHD-LOD children also differ from controls on a number of dimensions.This research was supported by grants from the Medical Research Council of Canada and the British Columbia Health Research Foundation. Appreciation is extended to Josie Geller, Kim Behrenz, Susan Greaves, and Sonia Pietzsch who assisted with data collection and coding, and to the families who generously gave their time to participate in the research. Thanks also to two anonymous reviewers for their comments.     

Reception of Morse code through motional, vibrotactile, and auditory stimulation

The potential for communication through the kinesthetic aspect of the tactual sense was examined in a series of experiments employing Morse code signals. Experienced and inexperienced Morse code operators were trained to identify Morse code signals that were delivered as sequences of motional stimulation through up-down displacements (roughly 10 mm) of the fingertip. Performance on this task was compared with that obtained for both vibrotactile and acoustic presentation of Morse code using a 200-Hz tone delivered either to the fingertip through a minishaker or diotically to the two ears under headphones. For all three modalities, the ability to receive Morse code was examined as a function of presentation rate for tasks including identification of single letters, random three-letter sequences, common words, and sentences. Equivalent word-rate measures (i.e., product of percent correct scores and stimulus presentation rate) were nearly twice as high for auditory presentation as for vibrotactile stimulation, which in turn was about 1.3 times that for motional stimulation. The experienced subjects outperformed the inexperienced subjects by amounts that increased with task complexity. For example, the former were able to receive sentences at 18 words/min with motional stimulation, whereas the latter, following 75 h of training, were unable to perform this task. The present results and those of other research with tactual communication systems are compared, particularly regarding estimates of information-transfer rates.     

Maternal characteristics,ratings of child behavior,and mother-child interactions in families of children with externalizing disorders

Relationships among maternal characteristics, ratings of child behavior, and observed mother-child interactions were examined in a sample of 40 4- to 12-year-old children with externalizing disorders. Mothers and children were observed in a task interaction and mothers provided self-reports of depressed mood, parenting self-esteem, marital satisfaction, social support, and life stress. Child behavior was rated by both mothers and teachers. Several significant correlations were found among observed mother and child behaviors and among maternal self-report measures. However, few significant relationships were found between maternal characteristics and observed mother or child behavior. Although life stress predicted increased child negativity, maternal depressed mood was related to more appropriate child behavior. Mother and teacher ratings of child behavior demonstrated few significant relationships with other measures. These results suggest that, in samples comprised primarily of children with attention deficit disorder from socially advantaged families, few relationships exist between maternal characteristics, parenting behavior, and child behavior.This study was part of a doctoral dissertation conducted by the first author at Florida State University, under the direction of the second author, and supported by the Social Sciences and Humanities Research Council of Canada. Portions of the data also appear in a chapter by Johnston titled A behavioral-family systems approach to assessment: Maternal characteristics associated with externalizing behavior in children. In R. Prinz (Ed.),Behavioral assessment of children and families (Vol. 4, pp. 163–189). Greenwich, CT: JAI Press. The authors express appreciation to Alan Lang, Barbara Licht, and Richard Tate, for their thoughtful comments. We are grateful to Beverley Atkeson and a dedicated group of coders and to Dr. C. E. Cunningham and the staff of the Chedoke Child and Family Center for their support. Finally, our thanks to the families who participated.     

Facilitating referential communication among children: The listener as teacher

This study was designed to test the hypothesis that systematic variations in listener behavior can have an important influence on both speaker behavior and communicative success among children. In particular, we investigated the idea that systematic variations in listener behavior might have not only within-trial effects on the adequacy of speakers' messages and the accuracy of communication among children, but also cumulative effects on speakers' initial messages across trials. Effects of stimulus complexity were also examined. Pairs of 7- and 9-year-old children participated in a referential communication game, with the younger child serving as speaker and the older one as listener. Half of the listeners were given a plan for effective listening which emphasized the importance of asking questions if the speakers' messages were ambiguous. Replicating earlier findings, the plan manipulation was successful in encouraging listeners to ask questions when necessary. The major result was that listener questions not only had the expected trial-by-trial effect on message adequacy and communicative accuracy, but also showed a cumulative effect on speaker performance. When exposed to systematic listener feedback, speakers improved their initial messages over trials. Stimulus complexity was not a major determinant of performances. These findings suggest that provision of systematic listener feedback may be an effective method for teaching speaker skills to young children.