Reaction Measurement Essay, Research Paper

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.

Cameron, D.L. (1995). Color-specificity to enhance identification of rear

lights. Perceptual and Motor Skills, 80(3): 755 – 769. Gottsdanker, R. &

Shraap, P. (1985) Verification of Donders’ subtraction method. Journal of

Experimental Psychology: Human perception and performance, 111(6), 765 – 776.

Hackley, S.A., Schaff, R. & Miller, J. (1990). Preparation for Donders’ Type

B and reaction tasks. Acta Psychologia, 74, 15 – 33. Rossenbaum, D.A. (1980).

Human movement initiation. Journal of Experimental Psychology: Specification of

aim, direction, and extent. General 109, 444 – 474. Weiten, W. (1998).

Psychology, Themes and Variations (4th Ed.) California: Brooks/Cole.