variety of research results suggest that visual images interfere with visual per
ID: 3159058 • Letter: V
Question
variety of research results suggest that visual images interfere with visual perception. In one study, Segal and Fusella (1970) had participants watch a screen, looking for brief presentations of a small blue arrow. On some trials, the participants were also asked to form a mental image (for example, imagine a volcano). The results show that participants made more errors while forming images than while not forming images. Data similar to the Segal and Fusella results are as follows. Do the data indicate a significant difference between the two conditions? Use a two-tailed test with " = .05.
Errors Errors
Participant with Image without Image
A 13 4 B 9 2
C 12 10 D 7 8
E 10 6 F 8 6 G 9 4
Explanation / Answer
The differences are (wihtout - with):
-9
-7
-2
1
-4
-2
-5
Formulating the null and alternative hypotheses,
Ho: ud = 0
Ha: ud =/ 0
At level of significance = 0.05
As we can see, this is a two tailed test.
Calculating the standard deviation of the differences (third column):
s = 3.22865954
Thus, the standard error of the difference is sD = s/sqrt(n):
sD = 1.220318602
Calculating the mean of the differences (third column):
XD = -4
As t = [XD - uD]/sD, where uD = the hypothesized difference = 0 , then
t = -3.277832523
As df = n - 1 = 6
Then the critical value of t is
tcrit = +/- 2.446911851
Also, using p values,
p = 0.016868209
As |t| > 2.447, and P < 0.05, WE REJECT THE NULL HYPOTHESIS.
Hence, there is a significant difference between the mean number of errors between the two conditions at 0.05 level. [CONCLUSION]
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