Screensaver reveals new test for synaesthesia
New Scientist, 04 August 2008
sounds like a Zen conundrum: what is the sound of dots moving? Most of
us can't answer that question, but for people with a newly identified
form of synaesthesia, hearing such sights is the most natural thing in
Melissa Saenz at Caltech in Pasadena was tipped off
when a visitor looked at her screensaver, which made no noise, and
said, "Does anyone else hear that?"
She quizzed him and found
that his experience had the hallmarks of synaesthesia: a trigger
through one sense was giving rise to a sensory experience in another.
It was automatic and her visitor had experienced it as far back as he
To round up a few more test subjects, she passed
around the noisy image via email. To her surprise, a few hundred
viewers yielded three more of the new synaesthetes.
them a variety of visual stimuli, from moving dots to flashes of light.
Depending on the stimulus, people described simple abstract sounds such
as tapping, thumping, whirring or whooshing.
and collaborator Christof Koch set out to develop a task that would
allow synaesthetes to outperform other people if the auditory sensation
Saenz knew that humans are able to judge patterns in
time much better using sound than vision, so she developed a simple
type of Morse code.
She asked her subjects to either listen to or watch two sequences before saying whether they were identical.
reality half were the same and half different. Everyone was about 85%
accurate on the sound trials, but whereas controls got only 55% of the
visual rhythms right, synaesthetes remained steady at 85%. As they
later reported, they were helped by being able to hear the flashes as
well as see them.
"The choice of task is great," says Jamie Ward at the University of Sussex in Brighton, UK. "You can't fake being better."
He adds that new types of synaesthesia are being uncovered all the time.
Saenz is following up her study with brain imaging and is also eager to recruit new subjects.
Journal reference: Current Biology (DOI: 10.1016/j.cub.2008.06.014)