West campus news Releases Archive
ASU student earns national neuropsychology award for subliminal vision learning research
Apr. 21, 2005
Results could lead to treatments for dyslexia and other reading disabilities
Steven R. Holloway, a student in Arizona State University’s New College of Interdisciplinary Arts and Sciences, has received an award from the National Academy of Neuropsychology for an outstanding research project related to perceptual learning.
“This line of research is producing very exciting results,” Holloway said. “We’re able to demonstrate with solid scientific evidence that people can learn things they can’t consciously see. And, the implications of this finding go well beyond perceptual learning. In fact, this research may eventually lead to treatments that will help people who suffer from various reading disabilities such as dyslexia.”
The research project, “Critical Flicker Fusion Threshold as a Function of Subliminal Neural Plasticity,” was presented late last year at the Academy’s 24th annual conference. The study was designed to test the relationship between the brain’s ability to perceive a flickering light and subliminal learning.
Critical flicker fusion (CFF) is the lowest level of continuous flicker that is perceived as a steady source of light. The team’s research suggests that a person’s CFF threshold can be modified, which could open the door to discovering a treatment for reading disabilities.
Holloway co-authored the study with Aaron R. Seitz, Harvard Medical School; José E. Náñez, Sr., Arizona State University; Michael Engles, University of Georgia; and Takeo Watanabe, Boston University.
Holloway majored in psychology as an undergraduate in the department of Social and Behavioral Sciences at ASU’s West campus under the tutelage of Náñez, an internationally recognized researcher in the fields of developmental cognitive neuroscience, infant development and biomedical research.
“This is the first non-reading paradigm to hold the potential to help people with reading disabilities,” Náñez said. According to Náñez, most paradigms tell you to “read more to read better.” While this may have some truth to it, the current research suggests that subliminal training can take place, he said.
“It’s a fascinating line of inquiry,” said Náñez, “and we’re very proud of Steve’s leadership on the project. He is a prime example of how highly motivated students can receive graduate-level research experience during their undergraduate years. His training in our Cognitive and Vision Sciences Laboratory at ASU’s West campus is clearly second to none.”
About the research
The ability to resolve visual modulation, or “flicker,” is believed to be limited by the primary visual system, because even though the eye can process high rates of flicker (up to 120 hertz, or cycles per second), the visual cortex cannot. Consequently, rates over approximately 22 hertz are perceived as a steady or unflickering light.
However, recent research conducted by Náñez, Watanabe, and Seitz, published in the international journals Nature and Nature Neuroscience has shown that perceptual learning can occur in the primary visual system as a result of exposure to subliminal stimuli. This concept, known as brain plasticity, demonstrates for the first time that neurons in this area of the visual cortex remain malleable into young adulthood by taking on new functions with repeated exposure to subliminal stimuli.
Using their research as a template, Holloway measured CFF thresholds while presenting subjects with subliminal dot motion as a background feature as they performed an unrelated letter-identification task. After several days of training, subjects improved their ability to identify the particular direction of motion that was paired with the targets of the letter task and increased their CFF thresholds by an average of 30 percent.
The results of the experiments show that this unique visual experience can dramatically increase a person’s CFF threshold—a finding not discovered until now, Holloway reports.
According to Holloway, this research eventually may lead to treatments that will help people who suffer from various reading disabilities. For instance, it is known that persons with dyslexia show reduced brain activity in the primary visual cortex, as well as in several higher levels of the primary visual cortex. Since these areas of the brain are believed to be responsible for regulating CFF, and they are the parts of the visual pathway believed to be involved in subliminal perceptual learning, functioning in these areas may be bolstered by such a learning process, he said.
Additionally, researchers have found that persons who suffer from dyslexia or other reading disabilities demonstrate a deficit in motion-detection tasks and are known to have lower CFF scores than persons who do not have these ailments.
“Significantly, the results of our study show a marked improvement in subjects’ CFF thresholds and their abilities to detect dot motion,” Holloway said. “If we’re correct, it’s possible that a positive collateral effect of our subliminal perceptual learning may strengthen the regions of the brain responsible for dyslexia and other reading difficulties.”
The National Academy of Neuropsychology is a professional society that includes clinicians, scientist-practitioners and researchers interested in neuropsychology. Neuropsychology involves the study, evaluation and treatment of known and suspected brain disorders using the methods of psychology. In earning this national award, Holloway was judged by leading professionals in the field against approximately 110 other research projects presented by students throughout North America.
Holloway also recently received a regional award for top research paper from Psi Chi, the National Honor Society in Psychology. This award, for his continuing research into critical flicker fusion and the implications for subliminal learning and brain plasticity, was presented April 16 at the society’s Rocky Mountain Psychological Association’s Regional Convention Program annual meeting in Phoenix.
PHOTO: Holloway checks a vision contrast sensitivity measuring tool used in perceptual experiments.
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