FREE ESSAY ON RULERS AND REACTION TIMES

RULERS AND REACTION TIMES

Rulers and Reaction Times
Abstract
The reaction time of ten subjects was measured. The subjects were asked to catch a ruler
ten times under five different conditions. The first condition measured the subject's
simple reaction time. Each further condition added an additional stimulus and the
reaction times were measured. There was a clear increase in reaction time with the
addition of further stimulus, however the expected result of a steady increase in
response time with the addition of each condition did not occur. The third condition
displayed the highest response time where as the final condition displayed the second
lowest (after condition 1). Assuming that no design problems in the experiment affected
the results, it cannot be concluded that cognitive processes occur in separate order and
do not overlap. Given the average reaction time of condition five was lower than
condition three, some cognitive adaption may have occurred to lower the response time of
the subjects or another reason may exist. One aspect not covered by the experiment, but
important to the results was the error factor. Pre-guessing the experimenter caused a
high rate of error, however it lowered the overall results.
Why measure response times?
As the world moves forward with technology, increasing pressure is placed upon humans to
be quicker, be smarter and to operate more efficiently. As the population increases
systems are being put in place to reduce incidences and accidents occurring. An example
of this is a study conducted by Cameron, 1995 examining the influence of specific light
colors, motor vehicle braking and the reaction time of the drivers to these specific
clouds and conditions to avoid rear end collisions. Donders subtractive method holds that
reaction times can be obtained by subtracting the simple reaction time; or subtracting
type A from type B etc. (Cameron, 1995). Given this, it stands that the more stimulus
provided (or thought processes required), the longer the response time of the subjects.
This theory is tested in the measurement of ten responses to five test conditions. The
trial provides preliminary information to participants and it is expected that reaction
times will be shorter than if no information was supplied. (Rosenbaum, 1980.)
Method
Participants
Ten participants were selected, four female and six male. Ages ranged from twenty-two to
fifty three. All were fully able bodied and from English speaking backgrounds.
Materials
A plastic yard rule was used. The yard rule was six centimeters in width.
Procedure
Condition One
The experimenter sat one subject on a chair and instructed them to place their arm out in
front of them at a comfortable height. The yard rule was then placed between the
subject's fingers at a height of 10 centimeters. The subject was then told the condition
1 (Appendix A) and given three trials. The subject then completed the ten tries at the
condition and the results were recorded. All ten subjects were tested in the same manner.
No abnormal results were obtained. 
Condition Two
The experimenter sat one subject on a chair and instructed them to place their arm out in
front of them at a comfortable height. The yard rule was then placed between the
subject's fingers at a height of 10 centimeters. The subject was then told the condition
2 (Appendix A) and given three trials. The subject then completed the ten tries at the
condition and the results were recorded. All ten subjects were tested in the same manner.
An error rate and abnormal results occurred.
Condition Three
The experimenter sat one subject on a chair and instructed them to place their arm out in
front of them at a comfortable height. The yard rule was then placed between the
subject's fingers at a height of 10 centimeters. The subject was then told the condition
2 (Appendix A) and given three trials. The subject then completed the ten tries at the
condition and the results were recorded. All ten subjects were tested in the same manner.
An error rate and abnormal results occurred.
Condition Four
The experimenter sat one subject on a chair and instructed them to place both their arms
out in front of them at a comfortable height. The yard rule was then placed between the
subject's hands at a height of 10 centimeters. The subject was then told the condition 4
(Appendix A) and given three trials. The subject then completed the ten tries at the
condition and the results were recorded. All ten subjects were tested in the same manner.
A high error rate and abnormal results occurred.
Condition Five
The experimenter sat one subject on a chair and instructed them to place both their arms
out in front of them at a comfortable height. The yard rule was then placed between the
subject's hands at a height of 10 centimeters. The subject was then told the condition 5
(Appendix A) and given three trials. The subject then completed the ten tries at the
condition and the results were recorded. All ten subjects were tested in the same manner.
A high error rate and abnormal results occurred.
Results
Then ten subjects all recorded faster reaction times for condition one than any of the
other conditions (Fig 1). On the surface this result would support the theory that the
more stimulus the slower the reaction time of the subject. When examined as a whole, this
is not strictly the case. Condition one averaged 180.3 milliseconds, condition two 240.5,
condition three 270, however, condition four averaged 254.4 and condition five only 238.2
milliseconds. 
Fig 1 - Average responses of subjects over five conditions.
Initially the introduction of more stimuli slowed the reaction time of the subject. The
reaction time of the subject did not, however slow from condition three to four and four
to five with more additions.
The standard deviation for condition one was also lower than any of the other conditions
(Fig 2). The deviation for condition one was 26.5, condition two 37.5, condition three
31.1, condition four 31.7 and condition five 28.8. The high variation for condition two
may be explained by the fact that it is the first introduction of an additional stimulus
over and above the simple response. 
Fig 2. Average responses of subjects and the standard deviation.
Discussion
The results show that an initial increase in the complexity of a task increases the
reaction time. According to Donders' Theory (Gottsdanker, R & Shraap, P., 1985) results
for Condition Five (Discrimination + Decoding + Response Selection) should be greater
than condition four (Discrimination + Response Selection) and condition three
(Discrimination and Decoding). Condition five, however, was faster in reaction time that
condition four and three (Fig 1). Shown only these results the conclusion may be drawn
that Donders theory is not entirely correct until the source, method and type of
experiment is examined. The biggest factor in the reduction of response time between
experiments three and four to experiment five was the error ratio. It was clear in the
experiment that the subjects were pre-guessing the experimenter. This was providing the
subject with a better result than if the subject was legitimately waiting for
instructions, as there was no penalty for incorrect responses. Nine out of the ten
subjects saw the experiment as a competition and therefore concentrated more on speed
that correctness. As in the case when the subject drops the ruler himself or herself or
when pre-advised of the requirement, the results are shorter as the processing time is
shorter when the subject has pre-ordained the response they will make. This limitation
was due mainly to the type of experiment conducted. Given the materials and the situation
it was not an accurate measure of response times as some subjects had thirty or forty
attempts before ten correct responses could be obtained. Although the logic of Donders'
Theory is relevant, in this case it cannot be ascertained conclusively that an increase
in tasks slowed the reaction time of the subjects. 
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