How long babies spent time looking at rotated blocks and the mirror images of blocks was a measure of the ability to mentally rotate an object.
gender gap in spatial abilities — charted for more than 30 years —
emerges within the first few months of life, years earlier than
previously thought, psychologists report.
typically outperform females on spatial-ability tests by age 4,
especially on tasks that require mental rotation of objects perceived
as three-dimensional. Yet, two studies of 3- to 5-month-olds, both
published in the November Psychological Science, conclude that a
substantially greater proportion of boys than girls distinguish a block
arrangement from its mirror image, after having first seen the block arrangement
rotated. Babies who prefer looking at the mirror image are presumed to
have mentally rotated the block arrangement, recognized it and chosen
to gaze at the novel mirror image.
One investigation was conducted by David Moore of Pitzer College in Claremont, Calif., and Scott Johnson of the University of California, Los Angeles. The other was directed by Paul Quinn of the University of Delaware in Newark and Lynn Liben of Pennsylvania State University in University Park.
Both sets of researchers suspect that sex differences in mental rotation develop shortly after birth due to an unknown mix of genetic, biological and environmental influences.
result we found was really somewhat of a shocker,” Moore says. He had
expected to demonstrate no sex difference in infants’ mental rotation
skills, laying the groundwork for pinpointing the age at which this
spatial gap first appears.
“Simultaneous reports by two different labs using two different techniques are difficult to dismiss,” remarks psychologist Nora Newcombe of Temple University in Philadelphia.
the new reports don’t confirm that baby boys perform mental rotation
tasks better than baby girls do, comments psychologist Susan Levine of
the University of Chicago. That’s because both studies first
familiarized babies with a block arrangement oriented at specific
angles but then presented it from a new angle for comparison with its
mirror image, a process that may mask baby girls’ spatial insights.
By 3 months of age, girls — but not boys — may notice changes in a block arrangement’s angle, Levine
proposes. If so, girls would regard both a newly oriented block
arrangement and its mirror image as novel, spending roughly equal
amounts of time looking at both. Scientists have yet to address this
possibility, she says.
If infant boys don’t notice angle shifts, they would spend most of the time looking at novel mirror images, Levine suggests. Baby boys would thus falsely appear to be better than baby girls at mental rotation.
“Even if there is an early advantage in favor of males, there is ample research showing that mental rotation skill is malleable,” Levine says.
Preschool activities such as block building, assembling jigsaw puzzles
and playing certain video games have been linked to stronger mental
rotation skill. In 2005, Levine reported that
second- and third-graders from poor families, who receive little or no
exposure to such activities, show no sex difference in the ability to
mentally rotate an object.
parents play with their children and babies in ways that promote
spatial thinking, such as naming the shapes of toys and guiding a
child’s hand to rotate a toy, notes Penn State’s Liben. It’s not known
whether parents target such behavior at boys, she says.
have yet to show that early proficiency on mental rotation tasks
translates into an aptitude for spatially challenging subjects such as
geometry, geography and science, Levine cautions.
Johnson showed 20 boys and 20 girls, all 5 months old, videos of a
block arrangement rotating back and forth through a 240° angle. Each
child sat in his or her mother’s lap as the mother kept her eyes
closed. After tiring of looking at this image, infants saw alternating
videos of the original block arrangement or its mirror image rotating
through a 120° angle.
of infants’ gaze and head movements revealed that 14 boys, or 70
percent of them, preferred looking at mirror images, compared with 9
girls, or 45 percent of them.
Quinn and Liben showed
12 boys and 12 girls, all 3 to 4 months old, a series of images of
either a black number 1 or its mirror image, each drawn to appear
three-dimensional and situated at a different degree of rotation. Each
baby then saw presentations of both the number 1 and its mirror image
in a new degree of rotation.
In the latter trials, 11 boys preferred looking at the image that they hadn’t seen before, compared with 5 girls.
It may be possible to study mental rotation in babies within the first few days after birth, Quinn says.