YOUR SENSE OF THE WORLD AND MOVEMENT WITHIN ITseparate “what” and “where” pathways for auditory processing, then it’s
very likely that we do too.
One obvious difference between hearing and vision is that we can close
our eyes but we can’t close our ears. This has psychological implications,
with recent research showing that exposure to too much noise can be
bad for your health, presumably because unwanted noise is so stressful.
For example, a Swedish epidemiological study led by Jenny Selander,
involving thousands of people, found evidence of a link between exposure
to traffic noise and the risk of having a heart attack – even after taking
account of the potentially contributory role played by air pollution.
At this point, as we go through the different senses, you might be
getting the impression that each sense functions entirely separately from
the others. The reality is that there is plenty of crosstalk between the
senses, even among the majority of us who don’t have synaesthesia (see
p.71). This is demonstrated dramatically in an illusion called the McGurk
effect, named after the psychologist Harry McGurk. It plays off the fact
that people’s lip movements influence what we hear. If you watch a video
of a person saying the sound “GA” but with the soundtrack altered to
Human echo-location
We usually think of humans as having five major senses – sight,
hearing, touch, taste and smell. Some psychologists might also add
proprioception to that list, which is the sense of where our limbs are
positioned in space, and perhaps also the vestibular senses (housed
in the inner ear and involving balance and orientation in space).
However, it’s probable that only a few people know about human
echo-location. This is the ability to detect, bat-like, where things are
by emitting sounds, for example by making a clicking noise with
the mouth, and listening for how those sounds echo back. In 2009
in Psychology Today magazine, psychologist Lawrence Rosenblum
documented a remarkable group of blind mountain-bikers – called
Team Bat – who use echo-location to detect obstacles as they are
riding along, albeit slowly and with a few wobbles (see the videos
section at http://www.worldaccessfortheblind.org). Also in 2009, in the
first systematic investigation of its kind, a research team led by Juan
Antonio Martínez confirmed that the palate clicks used by Daniel Kish,
leader of Team Bat, are the most effective sounds to use for echo-
location. The researchers added that anyone is capable of developing
echo-location skills and that after two hours practice a day for two
weeks, you should be able to detect blindfolded whether you have an
object in front of you or not.