Question

A cognitive Psychologist is interested to see if the color of ink affects information processing speed. Based on published studies, it is known that on average the general population takes µ = 1100 milliseconds to recognize common words like car or apple, but the standard deviation for the population varies across these studies, so we do not know the population deviation. A psychologist presents a sample of n = 36 participants with common words that are names of colors. However, the color names are printed in a color of ink different from the word itself. That is, the word red is printed in blue ink, or green is printed in brown etc. Mean recognition time for these words was M = 1180 msec, with a sample standard deviation of   S = 200 msec.

What is the type of statistical test you would use in this study? _____________________

What is the I.V.? ____________________   What is the D.V.? _____________________

Use the four steps of hypothesis testing, with alpha = .05, 2 tailed test and APA format to summarize your results and interpret your findings.

Step 1:

Step 2:

Step 3:

Step 4:

Summarize your results in APA format.

Answer 1

Given, M = 1180 msec, S = 200 msec and n = 36 participants

i)

t test why because we don't know the population standard deviation

ii)

Independent variable is color of ink

Dependent variable is information processing speed

iii)

alpha = .05

2 tailed test

1) Hypothesis:

H0: µ = 1100

Ha: µ not = 1100

2) Test:

t stat = (M-µ)/(S/SQRT(n)) = (1180-1100)/(200/SQRT(36)) = 2.4

3) Decision:

tc = 2.0301 (Use t table)

t stat > tc, reject H0

P value = 0.0218

P value < 0.05, Reject H0

4) Conclusion:

There is enough evidence to conclude that on average the general population takes different than 1100 milliseconds to recognize common words like car or apple at 5% significance level