Sight or Sound; A Study of Reaction Times
The reaction rate of individuals was tested in this experiment to determine
whether light or sound induces a faster response time. Each individual
participated in two separate tests in random order; one tested the reaction
time of a red light stimulus and the other tested reaction time to a buzzing
sound stimulus. Taking into consideration that light travels faster than
sound; it was hypothesized that light would be detected sooner than sound.
Each participant was told to press a button when they saw the light or
heard the sound; the operator varied the length of time between each trial and
the reaction time was recorded. Each individual completed 5 trials for each
type of stimulus. If light is actually detected sooner by the individual,
then the brain would process and react to that signal slightly sooner causing
the reaction time to be slightly faster than the reaction to sound.
Results from this experiment indicate that the reaction rate was
actually faster for the sound stimulus (mean= .2632 seconds) than for the
light stimulus (mean= .2895 seconds). This data was determined to be
insignificant, however, only slightly (P= .064).
These results are inconsistent with the prediction that the reaction
to light would be faster. Although the prediction was based on the hypothesis,
it is a proven fact that light does travel faster than sound so it can be
assumed that the error occurred in the interpretation of the facts and
inconsideration of other factors. There are other problems which may have
affected the accuracy of the data. This experiment was not isolated from other
distracting elements such as alternative light sources and sounds which could
have slowed reaction time for random trials causing misleading results. As
each participant became more comfortable with the task, the average time
became quicker which creates a greater range in time which reduces the
significance of the data, if a couple of practice trials had been conducted,
this problem could have been eliminated. Some problems are uncontrollable;
these can be variances in individual factors including energy and attention
levels and previous experience through activities like sports and video games.
These variances also cause the range in reaction times to be greater which
leads to less significant data.
According to studies such as those done by Brebner and Welford
published in 1980, mean auditory reaction times are .14-.16 seconds and mean
visual reactions times are .18-.2 seconds. The time it takes for the signal to
reach the brain was also found by these studies; it takes auditory
stimulus .08-.1 seconds to reach the brain while visual stimulus take .2-.4
seconds to reach the brain. (http://biae.clemson.edu/bpc/bp/Lab/110/reaction.htm).
Based on this information as well as that from our own experiment, a
new hypothesis and prediction can be proposed such that if it does takes
longer for light stimulus to reach the brain, then the reaction time to light
will be slower than the reaction time to sound.
Considering the theory of evolution, it must be assumed that the variation in
reaction times has some sort of purpose. One possible idea is that the fight
or flight instinct begins with the recognition of danger and in general
something which produces light has less potential to be dangerous than
something that produces sound. If someone were to shine a bright light in your
eyes, it would be less likely to make you jump instinctively than if someone
made a loud noise. This idea has been capitalized on by (guess who) the
entertainment industry. This idea has played a big part in nearly every scary
movie ever made, if you watch the movie with your ears plugged, you are less
likely to be affected by it. In the same way, your alarm clock would be more
likely to wake you up if it made noise rather than if it shone light.