Drawing is ancient; it is the only childhood cognitive behavior for which there is any direct evidence from the Upper Paleolithic. Do genes influence individual differences in this species-typical behavior, and is drawing related to intelligence (
g) in modern children? We report on the first genetically informative study of children’s figure drawing. In a study of 7,752 pairs of twins, we found that genetic differences exert a greater influence on children’s figure drawing at age 4 than do between-family environmental differences. Figure drawing was as heritable as
g at age 4 (heritability of .29 for both). Drawing scores at age 4 correlated significantly with
g at age 4 (
r = .33,
p < .001,
n = 14,050) and with
g at age 14 (
r = .20,
p < .001,
n = 4,622). The genetic correlation between drawing at age 4 and
g at age 14 was .52, 95% confidence interval = [.31, .75]. Individual differences in this widespread behavior have an important genetic component and a significant genetic link with
g.
In
1926, a young woman struggled to come up with a reliable way to measure the intelligence of young children. Florence Goodenough (1886–1959) conceived the idea of asking the children to draw a human figure. Her ability test was remarkable: It took 10 min or fewer to administer; it used cheap, familiar, and widely available materials; children enjoyed the task; and the test could be scored easily and reliably (
Brill, 1935;
Goodenough, 1926;
Oakland & Dowling, 1983). Crucially, it worked: Performance on the Goodenough Draw-a-Man Test correlated moderately with scores on time-consuming comprehensive IQ tests, and the test was both reliable and valid (
Abell, Wood, & Liebman, 2001;
Naglieri & Maxwell, 1981). Goodenough’s genius was to take a common childhood product and see its potential as an indicator of cognitive ability (
Abell et al., 2001;
Chambers, 1983;
Chappell & Steitz, 1993;
Jones & Rich, 1957;
Krohn & Traxler, 1979;
Plubrukarn & Theeramanoparp, 2003). The test was validated in several populations and used widely until its popularity declined in the 1970s, perhaps because it was considered by some researchers to be one of several projective techniques, including the Rorschach Test, that were not empirically well supported (
Lilienfeld, Wood, & Garb, 2000) for screening psychopathology (
Chapman & Chapman, 1967), which was not its original purpose. The test has not previously been analyzed in genetically informative samples, so the etiology of individual differences in children’s figure drawing is unsettled.
Behavioral genetic designs, such as the twin design comparing resemblance between identical (monozygotic, or MZ) twins and fraternal (dizygotic, or DZ) twins, are especially interesting to apply to differences in children’s drawings of human figures because such drawings seem so likely to be sensitive to family background, such as parental guidance and encouragement. It also seems intuitive that any relationship between early figure drawing and later intelligence would be caused by familial influences held in common between the two traits. It seems that children with ready access to pencils, paper, picture books, and so on would have better drawing skills than children brought up without those advantages. These credible scenarios can be tested empirically with a twin study (
Plomin, DeFries, Knopik, & Neiderhiser, 2013).
Another reason to examine drawing is that it is ancient and widespread; cave decorations have been dated to 40,000 years ago (
Pike et al., 2012;
Valladas et al., 1992). Humans’ adult ancestors sculpted clay models of the human figure and then fired the figurines in ash pits 14,000 years before making “useful” artifacts such as pots. Evidence that figurative drawing and sculpture were valued comes from the number of hours spent in creating them, and from the places within cave sites where the objects were stored (
Cook, 2013, p. 35). Behavior rarely fossilizes, yet it has been preserved, marvelously, in fresh and beautiful drawings (and sculptures) in places like the caves of Chauvet and Lascaux (
Bataille, 1955;
Chalmin et al., 2004;
Chauvet, Brunel, & Hillaire, 1995, p. 114), and no doubt many as-yet-undiscovered sites, given the paucity of the record (
Cook, 2013).
Here we report our findings from the first genetically informative study of individual differences in children’s figure drawings and their relation to intelligence measured a decade later. We aimed to discover (a) the extent to which (if any) genes influence individual differences in children’s drawings of human figures, (b) the extent to which the accuracy of such drawings is predictive of later intelligence, and (c) the extent to which genes that contribute to drawing at age 4 also contribute to intelligence up to a decade later//
