Sight or Sound; A Study of Reaction Times

 

Jessica Boat

Nikolai Daiss-Fechner

 

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.