Sense And Sensibility In Short-Term Memory
More than three centuries ago, Sir Isaac Newton reflected on the
similarities between the sense of hearing and the sense of sight.
Newton's speculations were impossible to test scientifically, until
now. A novel Brandeis University study confirms the Newtonian idea that
sight and sound are indeed parallel - at least when it comes to
encoding and retrieving short-term memories from the two senses.
Published in the open-access journal Public Library of Science Biology (PLoS),
the study was inspired by Newton's 1706 book, Opticks, and set out to
investigate whether sight and hearing behave similarly in encoding
short-term memories.
"Obviously, sound and light are physically different, processed by
different receptors - eyes and ears - and furthermore, processed in
different neural streams within the brain," explained coauthor Robert
Sekuler, a neuroscientist at the Volen National Center for Complex
Systems at Brandeis University, and an expert on the neural and
cognitive terrain associated with vision. "Previous studies that tried
to compare auditory and visual memory did little or nothing to put the
stimuli that would be remembered on equal footing - comparing 'apples
to apples' between the two senses."
"But in this study we used insights from neuroscience to identify test
materials in vision and hearing that the human brain would process and
treat in similar ways, and then we used these well-matched stimuli to
examine memory for studied lists of either auditory or visual items,"
said Sekuler.
The study used computer-generated visual images and sounds to test
auditory and visual memory mechanisms. Both the sounds and the visual
materials were intentionally unfamiliar to test subjects, who also
found it difficult to name the test items. The results were based on
behavioral measures and a computational model for memory.
"Memories are not exact representations of the past," said coauthor
Kristina Visscher, a post-doctoral fellow at Brandeis. "This study
shows that our representations of sight and sound get contorted on the
way to being remembered, and they get contorted in the same ways." The
errors we make in memory for sounds are the same types of errors we
make in memory for sight.
The first of its kind, the study opens the door to the tantalizing
possibility that, according to Visscher, "the brain, in this case at
least, is relatively uninventive: it may use fairly similar methods to
generate light-based and sound-based memories." So three centuries
after Newton published his inspired speculation, there is evidence that
his intuition was close to the mark.
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URLS: For a demonstration of the sounds used, see http://people.brandeis.edu/~sekuler/rippleSoundFiles/movingRippleSounds.html
For a demonstration (using visual stimuli) of the memory task used, see http://people.brandeis.edu/~sekuler/MemoryDemo/
Contact: Laura Gardner
Brandeis University
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