Sex Differences in Early Infancy

Minding the gap: a sex difference in young infants' mental rotation through thirty degrees of arc

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object's appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants' ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants' responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task.

Mastery-oriented motor competence intervention improves behavioral but not cognitive self-regulation in head start preschoolers: Randomized controlled trial results

Motor competence and self-regulation develop rapidly in early childhood; emerging work suggests motor competence interventions as a promising way to promote self-regulation (e.g., behavioral inhibition; cognitive flexibility) in young children. We tested the impact of a mastery-focused motor competence intervention (Children's Health Activity Motor Program [CHAMP])1 on behavioral and cognitive aspects of self-regulation among children attending Head Start. Grounded in Achievement Goal Theory, CHAMP encourages children's autonomy to navigate a mastery-oriented motor skill learning environment. Children (M age = 53.4 months, SD = 3.2) were cluster-randomized by classroom (6 per condition) to an intervention (n = 67) or control condition (n = 45). Behavioral self-regulation skills were assessed using the Head-Toes-Knees-Shoulders task (HTKS). Cognitive self-regulation skills were assessed using working memory and dimensional card-sorting executive function tasks. Random-effects hurdle models accounting for zero-inflated distributions indicated that children receiving CHAMP, versus not, were almost 3 times more likely to have non-zero HTKS scores at post-test; OR: 2.98 (CI 1.53, 5.81); however, there were no effects on any cognitive aspects of self-regulation (all p's > 0.05). Mastery climate motor competence interventions are an ecologically valid strategy that may have a greater impact on preschoolers' behavioral than cognitive aspects of self-regulation.

Sex Differences in Autism: Examining Intrinsic and Extrinsic Factors in Children and Adolescents Enrolled in a National ASD Cohort

Discernment of possible sex-based variations in presentations of autism spectrum disorder (ASD) symptoms is limited by smaller female samples with ASD and confounds with ASD ascertainment. A large national cohort of individuals with autism, SPARK, allowed parent report data to be leveraged to examine whether intrinsic child characteristics and extrinsic factors differentially impact males and females with ASD. Small but consistent sex differences in individuals with ASD emerged related to both intrinsic and extrinsic factors, with different markers for males and females. Language concerns in males may make discernment of ASD more straightforward, while early motor concerns in females may hamper diagnosis as such delays are not identified within traditional ASD diagnostic criteria.

Monkeys do not show sex differences in toy preferences through their individual choices

BACKGROUND

As interest in evaluating sex differences in nonhuman animals grows, the finding that male and female monkeys have toy preferences that differ, and that parallel those documented in human children, has garnered significant attention and is leveraged as an argument in favor of a biological contribution for human sex differences. To date, however, only two studies have investigated sex differences in monkeys' toy preferences, both documenting that males prefer toys considered to be "masculine" (such as vehicles) and females prefer toys considered to be "feminine" (such as dolls). Monkeys in these studies were tested in their social groups, making it hard to determine if the sex differences reported reflect actual individual preferences or result from social dynamics present at the time of testing.

METHOD

Here, we assessed the preferences of 14 rhesus macaques (N = 7 males; N = 7 females) who were singly tested in a choice test with a variety of toys characterized as masculine (hard non-zoomorphic wheeled toys), feminine (zoomorphic soft toys), neutral (hard non-zoomorphic toys) and ambiguous (zoomorphic or plush vehicles) based on criteria from previous studies.

RESULTS

Males and females showed similar preferences for neutral and "masculine" toys and preferred them (i.e., were more likely to interact with them) to "feminine" and sex-ambiguous toys. When they interacted with the toys, both males and females interacted more with neutral than with "masculine" toys. Females, but not males, interacted more with neutral and "masculine" toys than with "feminine" toys. The highest frequency of interaction for any single toy for the male monkeys was with the doll-standing is stark contrast to previous findings.

CONCLUSIONS

Our results contrast greatly with the previous study in rhesus monkeys, as well as findings in human children, suggesting that the previously documented sex differences are likely context dependent, and question the existence of a strong biological basis to sex differences in toy preferences.

The Predictive Role of Perceived Autonomy Support in Elementary School Children Physical Activity

The present article aimed to test a predictive model based on children's perception of autonomy support exercised by their physical education teachers in establishing a state of high motivational quality, which in turn leads to greater intention and physical activity. Participants were 502 elementary school students aged 9 to 11 years (52.59% males (9.47 ± 0.53 years old) and 47.41% females (9.54 ± 0.53 years old)), who completed a self-reported questionnaire of perceived autonomy support from physical education teachers, self-determination, intention to be physically active, and physical activity. Results showed that perceived autonomy support was positively related to autonomous motivation, which in turn was associated with intention and physical activity. In addition, the model did not present variations with respect to gender and confirmed the indirect effects of autonomous motivation on intention and practice of physical activity. Finally, we conclude on the importance of an adequate perception of autonomy support in students by their teachers for the establishment of an appropriate motivational state that could promote greater intention and physical activity. Thus, the motivational state acquired in physical education classes can be translated into intention and practice of physical activity in different contexts of students' daily lives.

Sex-related differences in the sagittal plane spinal angles in preschool and school-age children

Study aim: The study aimed to assess the differences in the magnitude of the anterior-posterior spinal curvatures depending on sex in children aged 5 and 9 years.

Material and methods: This prospective longitudinal observational study included 67 children (29 girls and 38 boys) in pre-school-age and school-age phases (the first examination at 5 years old and the second examination at 9 years old). Measurements of body weight and height were recorded. The computerized assessment of body posture was performed with the photo-grammetric method (MORA 4 Generation). The normality of the distribution of variables was assessed with the Shapiro-Wilk test. The Mann-Whitney U test was used to analyze the differences between the sexes in terms of body posture parameters and somatic parameters.

Results: There were no statistically significant sex-related differences in the values of parameters of the anterior-posterior spinal curvatures in 5-year-old children. In the group of 9-year-old children in the angle of lumbar lordosis, a significant difference between the sexes was found (U = 387.00, p < 0.05). Girls aged 9 had a significantly higher mean value of the angle of lumbar lordosis than boys at the same age (p < 0.05).

Conclusions: A sex-related difference was found in the magnitude of lumbar lordosis in school-age children. Understanding the gender differentiation of lumbar lordosis is the first step towards explaining the wide variability of normal lumbar lordosis in adults and the developmental and biomechanical differences between male and female lumbar spines.

Sex and gender differences in the development of empathy

The topic of typical sex and gender difference in empathy is examined in both a developmental and neuroscientific perspective. Empathy is construed as a multi-layered phenomenon with various degrees of complexity unfolding in ontogeny. The different components of empathy (i.e., affective, cognitive, and prosocial motivation) will be discussed as they interact and are expressed behaviorally. Significant sex/gender differences in empathy are discussed in relation to putative bottom-up or top-down processes underlying empathetic responses. The early onset and the pervasive presence of such sex/gender differences throughout the lifespan are further discussed in light of social and neurobiological modeling factors, including early socialization, brain's structural/functional variances, as well as genetics and hormonal factors.

Physical Activity Practice and Optimal Development of Postural Control in School Children: Are They Related?

Background: This study aims to analyze the effect of physical activity practice on the postural control state of school children. If such an effect was detected, the second aim of the study was to identify which specific capacities of postural control benefited the most from physical activity. Methods: A cross-sectional study was performed using a convenience sample of 118 healthy children (54 girls) with a mean age of 10.3 ± 1.2 years. Their weight and height were measured. The accelerometric assessment of balance included four different tests in static balance and walking. Results: Physical activity habit prevalence was 38.9% in girls and 60.9% in boys, and its frequency was 2.3 days per week in girls and 2.8 days in boys. The active children obtained lower accelerations, but the active and sedentary girls showed lower accelerometric values than the active boys. The logistic regression analysis demonstrated the influence of sex on the accelerations of the body (p < 0.001), regardless of the habit of physical activity. Conclusions: Active children have better postural control than sedentary children, although sedentary girls have better balance than active boys. Therefore, physical activity practice seems to favor a more efficient development of postural control, but it cannot level or reverse the effect of the neurophysiological factors that are conditioned by sex.

Different Dynamics of Sensory-Motor Development and Behavior During the Transitional Period in Puppies: Preliminary Results

Many studies have analyzed the behavior of puppies during their socialization period, while little attention has been paid to the transitional period, when vision and hearing develop. Here, we compared the average age of sensory and motor development, and the behavior among a total of 25 puppies. Each litter was videotaped during 1-hour daily sessions on postnatal days 10-21 and coded for the following mutually exclusive behavioral categories: sleeping, suckling and moving. The moving category included side-to-side head swinging, exploring, rolling and allogrooming. The opening of the eyelids, appearance of the startle response and ability to stand up with either the front or hind legs were identified. The duration and frequency of puppy behaviors varied significantly with breed and season of birth. Breed and gender differences in gross motor and sensory development were also observed. These findings may turn out to be crucial to enhance the welfare, standards of rearing, and behavioral interventions aimed at improving adaptability to novel stimuli in pet dogs.

Catechol-O-methyltransferase val(158)met Polymorphism Interacts with Sex to Affect Face Recognition Ability

The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme. The dopaminergic system has been implicated in face recognition, a form of cognition for which a female advantage has typically been reported. This study aimed to investigate potential joint effects of sex and COMT genotype on face recognition. A sample of 142 university students was genotyped and assessed using the Faces I subtest of the Wechsler Memory Scale - Third Edition (WMS-III). A significant two-way interaction between sex and COMT genotype on face recognition performance was found. Of the male participants, COMT val homozygotes and heterozygotes had significantly lower scores than met homozygotes. Scores did not differ between genotypes for female participants. While male val homozygotes had significantly lower scores than female val homozygotes, no sex differences were observed in the heterozygotes and met homozygotes. This study contributes to the accumulating literature documenting sex-specific effects of the COMT polymorphism by demonstrating a COMT-sex interaction for face recognition, and is consistent with a role for dopamine in face recognition.

Head Movement Dynamics During Play and Perturbed Mother-Infant Interaction

We investigated the dynamics of head movement in mothers and infants during an age-appropriate, well-validated emotion induction, the Still Face paradigm. In this paradigm, mothers and infants play normally for 2 minutes (Play) followed by 2 minutes in which the mothers remain unresponsive (Still Face), and then two minutes in which they resume normal behavior (Reunion). Participants were 42 ethnically diverse 4-month-old infants and their mothers. Mother and infant angular displacement and angular velocity were measured using the CSIRO head tracker. In male but not female infants, angular displacement increased from Play to Still-Face and decreased from Still Face to Reunion. Infant angular velocity was higher during Still-Face than Reunion with no differences between male and female infants. Windowed cross-correlation suggested changes in how infant and mother head movements are associated, revealing dramatic changes in direction of association. Coordination between mother and infant head movement velocity was greater during Play compared with Reunion. Together, these findings suggest that angular displacement, angular velocity and their coordination between mothers and infants are strongly related to age-appropriate emotion challenge. Attention to head movement can deepen our understanding of emotion communication.