REACTION-TIME AND MOVEMENT TIME
Task Description
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The person being tested will stand stationary on one of the switch mats.
React to the illumination of the light, move as quickly as possible, and contact the
second switch mat.
Record reaction-time and movement time
Complete 5 trials
Calculate the means for the 5 trials and record the values on the master score
sheet.
Make sure to also record “1” for male and “2” for female on the master score
sheet.
Reaction-Time
Trial 1______
Trial 2______
Trial 3______
Trial 4______
Trial 5______
Mean_______
Movement Time
Trial 1______
Trial 2______
Trial 3______
Trial 4______
Trial 5______
Mean_______
Statistical Analysis of Data
Reaction-time and movement time scores will be compiled for all 4 lab sections and emailed to you in an Excel file so that you can complete the following statistical analysis.
You will also be e-mailed a recent article (Der & Deary, 2006) that examined sex and
age-related differences in reaction-time.
1. Follow the procedures from the first lab to calculate a correlation between
reaction-time and movement time. Use “RT” and “MT” in the Name column.
2. A t-test for independent groups is used when the same variable has been measured
in two independent groups and you want to know whether the difference between
group means is statistically significant. "Independent groups" means that the
groups have different people in them and that the people in the different groups
have not been matched or paired in any way.
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Calculate a t-test to determine if males and females demonstrate
significant differences on reaction-time
Open another SPSS file by clicking on File, New, and Data
Click on Variable View tab
In the Name column type in “RT” and “Sex”
In the “Sex” row click on the Values box
In the dialogue box type “1” in value box and “Male” in the label box and
click on Add
Then type “2” in the value box and “Female’ in the label box and click on
Add
Click on OK when finished
Click on Data View
Copy and paste the scores from the Excel file into the appropriate columns
Click on Analyze, Compare Means, and Independent Samples T-Test.
Now, move RT into the Test Variable field.
Move Sex into the Grouping Variable field.
You will notice that there are question marks in the parentheses following
your independent variable in the Grouping Variable field. This is
because you need to define the particular groups that you want to
compare. To do so, click on Define Groups, and indicate the numeric
values that each group represents. In this case, you will want to put a "1"
in the field labeled Group 1 and a "2" in the field labeled Group 2. Once
you have done this, click on Continue.
Click on OK to run the t-test analysis
Interpreting the Output from Independent Samples t-test
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The first table lists the number of participants (N), mean, standard deviation, and
standard error of the mean for both of your groups.
The second table initially presents you with an F-test (Levene's test for equality of
variances) that evaluates the basic assumption of the t-test that the variances of
the two groups are approximately equal (homogeneity of variance). If the F value
reported here is very high and the significance level is very low--usually lower
than .05 or .01), then the assumption of homogeneity of variance has been
violated. If this is the case, you should use the t-test in the lower half of the table,
whereas if you have not violated the homogeneity assumption, you should use the
t-test in the upper half of the table.
If the value in the Sig. (2-tailed) column after the t-test column is ≤ .05, then there
are significant differences in males and females.
Click, copy, and paste the Independent Samples t-test box into the Word
document you will be handing in.
Questions
1. Is the relationship between reaction-time and movement time significant?
2. What percentage of variability in movement time can be accounted for by
variability in reaction-time?
3. Is there a significant difference between males and females on reaction-time?
4. Review the Der and Deary (2006) article before answering the following
questions:
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Are our lab results regarding male and female differences in reaction-time
consistent with the findings of Der and Deary? Explain your answer.
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What kind of age-related differences in reaction-time did Der and Deary
report?
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What are some of the potential real-life consequences for the age-related
changes in reaction-time?
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Why might these age-related changes in reaction time be even more
significant for women?
Bonus: What factors do you think might decrease the age-related changes in reactiontime? Find one supporting reference.