The water level task is a common measure of spatial reasoning.

<p>The goal is to determine the level of the water, after the glass is tipped. The task can involve asking people to draw a line showing this level in an empty glass, with the score as the degree of deviation from horizontal. Options can also be presented for people to choose among, as shown here.</p

Human condition-dependent physical traits disrupted by NTDs.

<p>Human condition-dependent physical traits disrupted by NTDs.</p

Infection with two common NTD parasites compromises boys’ fitness more strongly than that of girls.

<p>The results are based on the commonly used shuttle run measure, whereby fitness is determined by the number of 20-meter back-and-forth laps that can be completed in a fixed amount of time. The figure is based on data (combined across children and adolescents) presented in [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004489#pntd.0004489.ref101" target="_blank">101</a>].</p

Sexual or social selection will result in the elaboration of traits that enhance or signal competitive abilities or influence mate choices.

<p>The top distributions show how these evolutionary processes result in larger traits (red) in one sex versus the other (green); or larger sexually selected (red) than naturally selected (green) traits in the same individual. As shown by the bottom distributions, exposure to parasites or to other stressors often has stronger effects on the elaborated than the contrast trait.</p

In developing populations, the stressors associated with low socioeconomic status (SES) compromise boys’ height more than that of girls and girls’ pelvic development more than that of boys.

<p>The figure shows standard deviation (SD) differences (lower SES—higher SES) in height and pelvic width for 8- and 14-year-olds from lower SES and higher SES families from Tanzania. Values > 0 indicate children from lower SES families scored higher, whereas values < 0 indicate children from lower SES families scored lower. Eight-year-olds from lower SES families were somewhat taller than their higher SES peers, but this reversed for 14-year-olds. Critically, the SES differences across age were larger for boys’ height (SD = 1.98) than pelvic width (SD = 1.42), and were larger for girls’ pelvic width (SD = 1.75) than height (SD = 1.28). The figure is based on data presented in [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004489#pntd.0004489.ref118" target="_blank">118</a>].</p

Avian condition-dependent traits compromised by parasites.

<p>Avian condition-dependent traits compromised by parasites.</p

Results for Mixed Models Predicting Growth in 6^th-9^th Academic Achievement.

<p>Results for Mixed Models Predicting Growth in 6^th-9^th Academic Achievement.</p

Sex differences in mathematics (top) and reading performance (bottom).

<p>Top: For each PISA assessment, the sex differences in mathematics (boys’ performance – girls’ performance) is displayed for the 5th, 50th, and 95th percentile of the performance distribution. Bottom: Similar for sex differences in reading (girls’ performance – boys’ performance).</p

Children’s visuospatial memory predicts mathematics achievement through early adolescence

<div><p>A previous study showed that gains in visuospatial memory from first to fifth grade predicted end-of-fifth grade mathematics but not reading achievement, controlling other factors. In this follow up study, these relations were assessed from sixth to ninth grade, inclusive (n = 145). The results showed that growth in visuospatial memory across the elementary school years was related to growth in mathematics achievement after fifth grade, controlling intelligence, the central executive and phonological memory components of working memory, in-class attentive behavior, parental education, and fifth grade mathematics achievement. As found for fifth grade, this relation was not found for reading achievement after fifth grade. In total, the results suggest that visuospatial memory has a unique influence on ease of learning some types of mathematics and that this influence becomes more important across successive grades.</p></div

Descriptive Statistics and Correlations.

<p>Descriptive Statistics and Correlations.</p