How to measure working memory capacity in the change detection paradigm

Although the measurement of working memory capacity is crucial to understanding working memory and its interaction with other cognitive faculties, there are inconsistencies in the literature on how to measure capacity. We address the measurement in the change detection paradigm, popularized by Luck and Vogel (Nature, 390, 279-281, 1997). Two measures for this task-from Pashler (Perception & Psychophysics, 44, 369-378, 1988) and Cowan (The Behavioral and Brain Sciences, 24, 87-114, 2001), respectively-have been used interchangeably, even though they may yield qualitatively different conclusions. We show that the choice between these two measures is not arbitrary. Although they are motivated by the same underlying discrete-slots working memory model, each is applicable only to a specific task; the two are never interchangeable. In the course of deriving these measures, we discuss subtle but consequential flaws in the underlying discrete-slots model. These flaws motivate revision in the modal model and capacity measures.     

Prevalence of Anxiety and Depression in Australian Adolescents: Comparisons with Worldwide Data

Data from two Australian studies were combined so that the prevalence of anxiety and depression in a large, normative sample of Australian adolescents could be investigated. The combined sample comprised 1,299 adolescents randomly selected from metropolitan and country schools in Melbourne, a large Australian city. The data were examined in order to ascertain the percentages of adolescents who scored above the clinical cut-off on two self-report instruments-the Revised Children's Manifest Anxiety Scale (C. R. Reynolds & B. 0. Richmond, 1985) and the Reynolds Adolescent Depression Scale (W. M. Reynolds, 1986). The results of these analyses were then compared with previously reported prevalence rates from studies worldwide. This comparison revealed striking differences in the prevalence of anxiety and depression across different countries and cultures. Limitations attributable to different self-report measures and imposed-etic approaches are discussed. Issues pertaining to social and political climate are also raised.     

Reenactment of televised content by 2-year olds: toddlers use language learned from television to solve a difficult imitation problem

Parents commonly label objects on television and for some programs, verbal labels are also provided directly via voice-over. The present study investigated whether toddlers' imitation performance from television would be facilitated if verbal labels were presented on television via voice-over or if they were presented by parents who were co-viewing with their toddlers. Sixty-one 2-year olds were randomly assigned to one of four experimental groups (voice-over video, parent video, parent video no label, parent live) or to a baseline control condition. Toddlers were tested with novel objects after a 24h delay. Although, all experimental groups imitated significantly more target actions than the baseline control group, imitation was facilitated by novel labels regardless of whether those labels were provided by parents or by voice-over on television. These findings have important implications for toddler learning from television.     

Bilateral capacity for speech sound processing in auditory comprehension: evidence from Wada procedures

Data from lesion studies suggest that the ability to perceive speech sounds, as measured by auditory comprehension tasks, is supported by temporal lobe systems in both the left and right hemisphere. For example, patients with left temporal lobe damage and auditory comprehension deficits (i.e., Wernicke's aphasics), nonetheless comprehend isolated words better than one would expect if their speech perception system had been largely destroyed (70-80% accuracy). Further, when comprehension fails in such patients their errors are more often semantically-based, than-phonemically based. The question addressed by the present study is whether this ability of the right hemisphere to process speech sounds is a result of plastic reorganization following chronic left hemisphere damage, or whether the ability exists in undamaged language systems. We sought to test these possibilities by studying auditory comprehension in acute left versus right hemisphere deactivation during Wada procedures. A series of 20 patients undergoing clinically indicated Wada procedures were asked to listen to an auditorily presented stimulus word, and then point to its matching picture on a card that contained the target picture, a semantic foil, a phonemic foil, and an unrelated foil. This task was performed under three conditions, baseline, during left carotid injection of sodium amytal, and during right carotid injection of sodium amytal. Overall, left hemisphere injection led to a significantly higher error rate than right hemisphere injection. However, consistent with lesion work, the majority (75%) of these errors were semantic in nature. These findings suggest that auditory comprehension deficits are predominantly semantic in nature, even following acute left hemisphere disruption. This, in turn, supports the hypothesis that the right hemisphere is capable of speech sound processing in the intact brain.     

Young children's social networks as a function of age and dysfunction

Social networks provide a larger context than that of the nuclear family in which the child develops. In order to examine the networks of young children, mothers of 75 handicapped children, aged 3 to 6 years, and a matched sample of normal children were surveyed in terms of people in the child's network and frequency of daily contact. The effects of age of subject and handicapping condition on social network composition and contact were of interest. Handicapping condition played a much greater role in the network composition than did chronological age. Handicapped children had larger networks, although they did not have daily contact with network members compared to normal children. Handicapped children thus were not isolated, but appeared to have a large network composed of relatives and adults and, to a lesser extent, peers. Normal children showed a developmental shift, in terms of an increase in the proportion of peers to adults, from 3 to 6 years, whereas handicapped children did not show this change. It is suggested that the handicapped child's developmental delay and caregiving demands may necessitate greater and more prolonged adult contact, which, consequently, constrains the nature of the social network in terms of adult and peer composition. Insufficient peer contact may restrict the handicapped child's opportunity to learn important social skills.     

Social psychology of mental health: the social structure and personality perspective

Previous research has revealed a persistent association between social structure and mental health. However, most researchers have focused only on the psychological and psychosocial aspects of that relationship. The present paper indicates the need to include the social and structural bases of distress in our theoretical models. Starting from a general social and psychological model, our research considered the role of several social, environmental, and structural variables (social position, social stressors, and social integration), psychological factors (self-esteem), and psychosocial variables (perceived social support). The theoretical model was tested working with a group of Spanish participants (N = 401) that covered a range of social positions. The results obtained using structural equation modeling support our model, showing the relevant role played by psychosocial, psychological and social, and structural factors. Implications for theory and intervention are discussed.     

A critical evaluation of c as a measure of mnemonic resolution

It is known that visual working memory capacity is limited, but the nature of this limit remains a subject of controversy. Increasingly, two factors are thought to limit visual memory: an object-based limit associated with so-called "slots" models, and an information-based limit associated with resource models. Recently, Barton, Ester, and Awh (2009) introduced a measure of mnemonic resolution, which they dubbed c. We show here that c is critically flawed, and cannot be interpreted as a measure of resolution. We recommend strongly against its use and interpretation, and suggest alternatives approaches for researchers who want to explore mnemonic resolution.