Frontal electroencephalogram alpha asymmetry during sleep: stability and its relation to affective style

Electroencephalogram (EEG) alpha (8-12 Hz) asymmetries were collected from the mid-frontal and central regions during presleep wakefulness and Stage 1, Stage 2, and rapid eye movement (REM) sleep in 11 healthy right-handed participants who were free of psychiatric, neurological, and sleep problems. The authors found significant correlations between presleep wakefulness and different stages of sleep in the frontal, but not central, EEG alpha asymmetry measure. The strongest correlation was between presleep waking and REM sleep, replicating and extending relation earlier work to a normal population. The high degree of association between presleep waking and REM sleep may be a result of high cortical activation common to these states and may reflect a predisposition to different styles of emotional reactivity.     

The body-inversion effect

Researchers argue that faces are recognized via the configuration of their parts. An important behavioral finding supporting this claim is the face-inversion effect, in which inversion impairs recognition of faces more than nonface objects. Until recently, faces were the only class of objects producing the inversion effect for untrained individuals. This study investigated whether the inversion effect extends to human body positions, a class of objects whose exemplars are structurally similar to each other. Three experiments compared the recognition of upright and inverted faces, houses, and body positions using a forced-choice, same/different paradigm. For both reaction time and error data, the recognition of possible human body postures was more affected by inversion than the recognition of houses. Further, the recognition of possible human body postures and recognition of faces showed similar effects of inversion. The inversion effect was diminished for impossible body positions that violated the biomechanical constraints of human bodies. These data suggest that human body positions, like faces, may be processed configurally by untrained viewers.     

Expertise in tactile pattern recognition

This article explores expertise in tactile object recognition. In one study, participants were trained to differing degrees of accuracy on tactile identification of two-dimensional patterns. Recognition of these patterns, of inverted versions of these patterns, and of subparts of these patterns was then tested. The inversion effect (better recognition of upright than inverted patterns) and the part-whole effect (better recognition of the whole than a part pattern), traditionally considered signatures of visual expertise, were observed for tactile experts but not for novices. In a second study, participants were trained as visual or tactile experts and then tested in the trained and nontrained modalities. Whereas expertise effects were observed in the modality of training, cross-modal transfer was asymmetric; visual experts showed generalization to haptic recognition, but tactile experts did not show generalization to visual recognition. Tactile expertise is not obviously attributable to visual mediation and emerges from domain-general principles that operate independently of modality.     

Priming infants to attend to color and pattern information in an individuation task

Wilcox (Cognition 72 (1999) 125) reported that infants are more sensitive to form than surface features when individuating objects in occlusion events: it is not until 7.5 months that infants spontaneously use pattern information, and 11.5 months that they spontaneously use color information, as the basis for object individuation. The present research assessed the extent to which infants' sensitivity to surface features could be increased under more supportive conditions. More specifically, we examined whether younger infants could be primed to draw on color and pattern features in an individuation task if they were first shown the functional value of attending to color and pattern information (i.e. the color or the pattern of an object predicted the function it would engage in). Five experiments were conducted with infants 4.5 to 9.5 months of age. The main findings were that 9.5- and 7.5-month-olds could be primed to use color information, and 5.5- and 4.5-month-olds could be primed to attend to pattern information, after viewing the function events. The results are discussed in terms of the kinds of experiences that can lead to increased sensitivity to surface features and the mechanisms that support feature priming in young infants.     

Lexical orthographic knowledge develops from the beginning of literacy acquisition

This study reports two experiments assessing the spelling performance of French first graders after 3 months and after 9 months of literacy instruction. The participants were asked to spell high and low frequency irregular words (Experiment 1) and pseudowords, some of which had lexical neighbours (Experiment 2). The lexical database which children had been exposed to was strictly controlled. Both a frequency effect in word spelling accuracy and an analogy effect in pseudoword spelling were obtained after only 3 months of reading instruction. The results suggest that children establish specific orthographic knowledge from the very beginning of literacy acquisition.     

Sex and age modulate the visual perception of distance

An experiment was conducted to evaluate the ability of 28 younger and older adults to visually bisect distances in depth both indoors and outdoors; half of the observers were male and half were female. Observers viewed 15-m and 30-m distance extents in four different environmental settings (two outdoor grassy fields and an indoor hallway and atrium) and were required to adjust the position of a marker to place it at the midpoint of each stimulus distance interval. Overall, the observers’ judgments were more accurate indoors than outdoors. In outdoor environments, many individual observers exhibited perceptual compression of farther distances (e.g., these observers placed the marker closer than the actual physical midpoints of the stimulus distance intervals). There were significant modulatory effects of both age and sex upon the accuracy and precision of the observers’ judgments. The judgments of the male observers were more accurate than those of the female observers and they were less influenced by environmental context. In addition, the accuracies of the younger observers’ judgments were less influenced by context than those of the older observers. With regard to the precision of the observers’ judgments, the older females exhibited much more variability across repeated judgments than the other groups of observers (younger males, younger females, and older males). The results of our study demonstrate that age and sex are important variables that significantly affect the visual perception of distance.     

Assessing the effectiveness of drawing an autobiographical memory as a mood induction procedure in children

The objective of our study was to examine the effectiveness of a new version of the autobiographical recall procedure (i.e., drawing a happy personal event) in eliciting a positive mood in 6-, 8-, and 10-year-old children and to compare the drawing condition to the more classical telling condition. The mood of children was assessed before and after induction using the Self-Assessment Manikin (SAM) and across the two emotional dimensions of valence and arousal. The results showed that the drawing condition was as effective as the telling condition for inducing a positive mood. Furthermore, in the drawing condition, children reported feeling calmer than in the telling condition, suggesting that drawing was more likely to help children regulate their emotional state. The drawing procedure could be used in future research aiming to induce positive moods in school-aged children, to help further investigate the relationship between cognition and emotion.     

The relationship between sleep and working memory in children with neurological conditions

The objective of this study is to investigate whether sleep problems might account for the increased working memory deficits observed in school-aged children with neurological conditions. A novel, transdiagnostic approach to the investigation was chosen, and sleep is treated as a process that can potentially account for working memory difficulties across a range of neurological conditions. Prevalence estimates of sleep problems are also examined. Archival data of 237 children aged 6 to 11 years were collected from a Western Australian statewide neuropsychological service for the period 26 July 2011 to 14 January 2014. Measures of parent-reported sleep quality, snoring, and daytime sleepiness were obtained, in addition to objective measures of verbal and spatial working memory, storage capacity, and processing speed. The results of the data analysis reveal that over one third of participants reported having clinically-significant levels of sleep problems and that poor sleep quality is significantly associated with verbal working memory difficulties. This association remains after partialling out the variance contributed to performance by storage capacity and processing speed, suggesting that sleep is impacting upon an executive component of working memory. No other significant associations are observed. The results suggest that poor sleep quality is associated with an executive component of verbal (rather than spatial) working memory in children with neurological conditions. This has implications for the biological mechanisms thought to underlie the relationship between sleep and cognition in children. The results also demonstrate the clinical utility of a transdiagnostic approach when investigating sleep and cognition in children with neurological conditions.     

The relationship between sleep problems and working memory in children born very preterm

In two studies, the relationship between sleep and working memory performance was investigated in children born very preterm (i.e., gestation less than 32 weeks) and the possible mechanisms underlying this relationship. In Study 1, parent-reported measures of snoring, night-time sleep quality, and daytime sleepiness were collected on 89 children born very preterm aged 6 to 7 years. The children completed a verbal working memory task, as well as measures of processing speed and verbal storage capacity. Night-time sleep quality was found to be associated with verbal working memory performance over and above the variance associated with individual differences in processing speed and storage capacity, suggesting that poor sleep may have an impact on the executive component of working memory. Snoring and daytime sleepiness were not found to be associated with working memory performance. Study 2 introduced a direct measure of executive functioning and examined whether sleep problems would differentially impact the executive functioning of children born very preterm relative to children born to term. Parent-reported sleep problems were collected on 43 children born very preterm and 48 children born to term (aged 6 to 9 years). Problematic sleep was found to adversely impact executive functioning in the very preterm group, while no effect of sleep was found in the control group. These findings implicate executive dysfunction as a possible mechanism by which problematic sleep adversely impacts upon cognition in children born very preterm, and suggest that sleep problems can increase the cognitive vulnerability already experienced by many of these children.