Typical development of quantity comparison in school-aged children

Although basic numerical skills have been widely studied in the last years, very few studies have undertaken a developmental approach. The present study evaluated the development of the magnitude comparison basic numerical ability, in children from first, third and sixth grades by means of the subject's response time in numerical tasks presented in symbolic and non-symbolic formats. The results showed a significant decrease on quantities processing speed as age increases, which suggests numerical skills tend to become automatic with instruction. The differences found, concerning the general achievement pattern in each school year, might express the maturational specificities of the numerical representation system through development.     

Event-related EEG oscillations to semantically unrelated words in normal and learning disabled children

Learning disabilities (LD) are one of the most frequent problems for elementary school-aged children. In this paper, event-related EEG oscillations to semantically related and unrelated pairs of words were studied in a group of 18 children with LD not otherwise specified (LD-NOS) and in 16 children with normal academic achievement. We propose that EEG oscillations may be different in LD NOS children versus normal control children that may explain some of the deficits observed in the LD-NOS group. The EEGs were recorded using the 10/20 system. EEG segments were edited by visual inspection 1000ms before and after the stimulus, and only correct responses were considered in the analysis. Time-frequency (1-50Hz) topographic maps were obtained for the increases and decreases of power after the event with respect to the pre-stimulus average values. Significant differences between groups were observed in the behavioral responses. LD-NOS children show less number of correct responses and more omissions and false alarms than the control group. The event-induced EEG responses showed significant differences between groups. The control group showed greater power increases in the frequencies 1-6Hz than the LD-NOS group from 300 to 700ms. These differences were mainly observed in frontal regions, both to related and non-related words. This was interpreted as a deficit in attention, both to internal and external events, deficits in activation of working memory and deficits in encoding and memory retrieval in the LD-NOS children. Differences between groups were also observed in the suppression of alpha and beta rhythms in the occipital regions to related words in frequencies between 8 and 17Hz from 450 to 750ms. LD-NOS children showed shorter durations of the decreases in power than the control group. These results suggest also deficits in attention and memory retrieval. It may be concluded that LD-NOS children showed physiological differences from normal children that may explain their cognitive deficiencies.     

Prosocial tendencies predict friendship quality, but not for popular children

Is prosocial behavior a prerequisite for having good-quality friendships? This study (N = 477, mean age = 12.2 years) examined whether the link between children’s prosocial tendencies and their perceived friendship quality was dependent on children’s level of popularity in the peer group. Children’s prosocial tendencies were assessed both as observed behavior in a standardized setting and as a self-reported predisposition to act in prosocial ways. Across measures, the results showed that prosocial tendencies are associated with higher perceived friendship quality among nonpopular children (i.e., children holding average or lower levels of popularity), but not among popular children. Thus, even if they lack prosocial qualities, popular children are still able to hold good-quality friendships. Popular children may have other compensating characteristics, such as popularity by association, that make them attractive for peers to be friends with.     

When voices get emotional: A corpus of nonverbal vocalizations for research on emotion processing

Nonverbal vocal expressions, such as laughter, sobbing, and screams, are an important source of emotional information in social interactions. However, the investigation of how we process these vocal cues entered the research agenda only recently. Here, we introduce a new corpus of nonverbal vocalizations, which we recorded and submitted to perceptual and acoustic validation. It consists of 121 sounds expressing four positive emotions (achievement/triumph, amusement, sensual pleasure, and relief) and four negative ones (anger, disgust, fear, and sadness), produced by two female and two male speakers. For perceptual validation, a forced choice task was used (n = 20), and ratings were collected for the eight emotions, valence, arousal, and authenticity (n = 20). We provide these data, detailed for each vocalization, for use by the research community. High recognition accuracy was found for all emotions (86 %, on average), and the sounds were reliably rated as communicating the intended expressions. The vocalizations were measured for acoustic cues related to temporal aspects, intensity, fundamental frequency (f0), and voice quality. These cues alone provide sufficient information to discriminate between emotion categories, as indicated by statistical classification procedures; they are also predictors of listeners’ emotion ratings, as indicated by multiple regression analyses. This set of stimuli seems a valuable addition to currently available expression corpora for research on emotion processing. It is suitable for behavioral and neuroscience research and might as well be used in clinical settings for the assessment of neurological and psychiatric patients. The corpus can be downloaded from Supplementary Materials.     

Family-Friendly Environments and U.S. Army Soldier Performance and Work Outcomes

This study examined how perceptions of a family-friendly environment relate to physical fitness, efficacy beliefs, and intentions to remain in the military. Survey data and actual performance measures from 230 U.S. Army soldiers were examined. Findings indicated that a perceived family-friendly environment was positively related to intentions to remain in the military upon fulfillment of obligation. Additionally, perceptions of family-friendly environments were positively related to collective efficacy perceptions. These findings provide strong support for the need to create and maintain a strong family-friendly work environment, not only to improve the well-being of employees but also to benefit the organization's retention efforts, obtained from employees being more willing to remain with the organization.     

Crime and violence in Brazil: Systematic review of time trends,prevalence rates and risk factors

Between 1980 and 2010 there were 1 million homicides in Brazil. Dramatic increases in homicide rates followed rises in inequality, more young men in the population, greater availability of firearms, and increased drug use. Nevertheless, disarmament legislation may have helped reduce homicide rates in recent years. Despite its very high rate of lethal violence, Brazil appears to have similar levels of general criminal victimization as several other Latin American and North American countries. Brazil has lower rates of drug use compared to other countries such as the United States, but the prevalence of youth drug use in Brazil has increased substantially in recent years. Since 1990, the growth of the Brazilian prison population has been enormous, resulting in the fourth largest prison population in the world. Through a systematic review of the literature, we identified 10 studies assessing the prevalence of self-reported offending in Brazil and 9 studies examining risk factors. Levels of self-reported offending seem quite high among school students in Brazil. Individual and family-level risk factors identified in Brazil are very similar to those found in high-income countries.     

Ontogeny of meal patterning in rats and its recapitulation during recovery from lateral hypothalamic lesions.

The development of feeding patterns was investigated in weanling rats and in rats with lateral hypothalamic lesions. From 16 to 25 days of age, the weanlings demonstrated a preprandial intake pattern, i.e., a positive correlation between meal size and time since the preceding meal. This subsequently declined while the postprandial relationship (correlation with time until subsequent meal) began to emerge such that by 30-35 days of age a full adult pattern was observed. Rats recovering from lateral hypothalamic lesions, for a brief period, also demonstrated a preprandial intake pattern. The postprandial relationship was abolished by the lesions. These results suggest that the development of adult meal patterning results from maturation of lateral hypothalamic mechanisms governing meal initiation.     

An automated swim alley for small animals: I. Instrumentation

A swim alley for testing the long-term performance capacity of rats is described. Rats swim back and forth in an alley, in temperature-controlled water, between platforms that are alternately and automatically raised and lowered. At the end of each traverse, an animal is allowed to rest on a raised platform for a period of time before the platform is lowered, which initiates the next traverse. Continuous measurement is made of speed of movement between platforms.     

Sex differences in the patterning of adult roles as a determinant of sex differences in occupational achievement

A sample of 4,035 men and women from the Project TALENT high school class of 1963 cohort was examined to determine the extent to which sex differences in the patterning of adult roles contribute to observed sex differences in occupational achievement. Men and women were found to differ in the comparative timing, ordering, and continuity of educational, occupational, marital, and procreational roles in early adulthood. These differences in role patterns explained only a small portion of the observed sex differences in occupational attainment, as sex appeared to be a strong direct determinant of both role patterns and attainment. However, some aspects of the patterning of these roles appeared to have an independent influence on occupational attainment; in these instances, the patterns associated with lower earnings were more likely to have been followed by women. Further investigation of the impact of variations in the patterning of adult roles on women's (and men's) occupational achievement is recommended.This work was supported by Grant MH29509 from the National Institute of Mental Health.