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By Bob Calverley
The USC News Service
USC researchers have found that one of the largest known cognitive
differences between men and women, that of mental rotation, disappears when subjects are tested using virtual reality technology.
The ability to orient objects spatially in one’s mind is known as mental rotation and is usually measured by a
standard pencil-and-paper psychological test, said Albert Rizzo. Rizzo is a clinical psychologist and research assistant professor with the Integrated Media
Systems Center at USC’s School of Engineering and the Alzheimer’s Disease Research Center.
Last fall, Rizzo tested 60 men and women between the ages of 18 and 34 with the standard mental rotation test, and again using a virtual reality system.
In the pencil-and-paper test, subjects look at a series of line drawings showing a target object and four other objects. Two of the drawings in each set show
the target object from different angles while the remaining two objects are mirror images of the target. Subjects must pick out the two objects matching the target
and have five minutes to correctly complete as many sets as they can.
“As expected, the men scored significantly better than the women,” Rizzo said. “Men consistently score higher than women on the mental rotation test, and previous
research has found an inverse relationship between estrogen levels and spatial ability.”
In the virtual reality tests, subjects wear special eye glasses and look at a 4-by-5-foot rear-projected computer screen. They see two large, three-dimensional
block objects, similar to the ones in the paper test, which appear to be floating in space in front of them. The objects are identical but presented at different
angles. Using a hand control the size of a tennis ball, subjects manipulate one of the objects until it fits exactly onto the other object. Then, two more objects
appear for them to match.
“In contrast to our hypothesis, we did not find any gender differences in the virtual reality tests of mental rotation,” Rizzo said. “Women can see and manipulate
the three-dimensional objects as efficiently and as quickly as men, but they can’t visualize the same process as well on paper. This has potentially profound
implications for understanding brain functioning.”
In the final phase of the study, subjects retook the pencil-and-paper test, with different figures, and those who had done poorly the first time improved their
scores significantly, while others did not improve or improved only slightly.
“This suggests that we can use virtual reality to help people with poor rotational skills to improve them,” Rizzo said. “We believe this technology will become a
valuable rehabilitation tool for people with many different kinds of cognitive deficits.”
Rizzo notes that the ability to turn over or manipulate objects mentally applies to many everyday life situations such as driving, sports or packing items into limited
storage space. It has also been linked to high-level mathematics performance, and Rizzo said poor scores on mental rotation tests may be one reason why
women are underrepresented in engineering, design and architecture.
Mental rotation is also an important test used for diagnosing traumatic brain injuries and to distinguish between Alzheimer’s and other dementias.
“Most Alzheimer’s patients have significant spatial orientation impairments, while those with some other forms of dementia don’t,” Rizzo said.
“In contrast to our hypothesis, we did not find any gender differences in the virtual reality tests of mental rotation. ... This has potentially profound implications for understanding brain functioning.”
– Albert Rizzo
The next virtual reality tests will be given to a group of seniors, age 65 and above, he said; then the researchers hope to work with Alzheimer patients and patients
with other dementias. The researchers have also begun designing a virtual environment to test children with attention deficit disorder.
“We think that researchers and clinicians will be able to obtain more reliable, ecologically valid and precise information about human cognition with this new
technology,” Rizzo said. “They’ll be able to accurately record a wider range of behavioral responses than is possible when using standard cognitive assessment
tests, some of which haven’t changed for 30 years.”
The research has many potential implications, said Chrysostomos “Max” Nikias, director of the IMSC. “The systematic evaluation of cognitive abilities in immersive
virtual environments will provide crucial information for designing effective human computer interfaces,” he said.
“In addition to gender differences, we must be concerned with issues such as side effects,” Nikias said.
Some people experience a form of motion sickness called “cybersickness” when using fully immersive virtual reality, and military research with flight simulators
suggests that women are more susceptible, Rizzo said.
“But we found no differences and had almost no problem with side effects,” he said. “Cybersickness is particularly important when working with neurologically
impaired populations, some of whom already have equilibrium, balance and orientation difficulties. We are also anxious to see how seniors react to this technology,
because most research in this area has been done with young people.”
The virtual reality research has been published in Cyber-Psychology and Behaviorand the Journal of Head Trauma Rehabilitation. The study on gender
differences was presented at a recent conference, “Medicine Meets Virtual Reality,” by graduate student Peter Larson. Other researchers working on the
virtual reality project include research assistant professor Galen Buckwalter, assistant professor Ulrich Neumann, project leader Carl Kesselman, and
programmer Marcus Thiebaux.
The research is funded by the National Institute of Aging.
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