Instructions: In 1974, Loftus and Palmer conducted a classic study demonstrating how the language used to ask a question can influence eyewitness memory. In the study, college students watched a film of an automobile accident and then were asked questions about what they saw. One group was asked, “About how fast were the cars going when they smashed into each other?” Another group was asked the same question except the verb was changed to “hit” instead of “smashed into.” The “smashed into” group reported significantly higher estimates of speed than the “hit” group. You, as a researcher wonder if Loftus and Palmer’s study is reliable, and repeats this study with a sample of FIU students and obtains the following data.
Hit Group 
Smashed Into Group 

32 
50 

26 
44 

40 
54 

23 
45 

42 
44 

20 
40 

37 
49 

25 
34 

24 
38 

22 
30 

19 
50 

24 
46 

19 
40 

22 
35 

29 
43 

24 
41 

34 
30 

33 
39 

37 
44 

20 
35 
1. Determine the value needed to reject the null hypothesis. Remember to calculate the correct degrees of freedom before finding the critical tvalue! Note whether it is best to use the onetailed or twotailed test.
2 . Compare the obtained and critical value
Obtained Value: Critical Value:
3 .Decide whether you will retain the null hypothesis or …
1. The value is 0.05.
2. Obtained Value: 6.299 Critical Value: 1.686
3. reject the null hypothesis
Cohen’s D = 13.95/7.003 = 1.99
Hit Group  Smashed Into Group  
27.60  41.55  mean 
7.34  6.64  std. dev. 
20  20  n 
38  df  
13.950  difference (Hit Group  Smashed Into Group)  
49.046  pooled variance  
7.003  pooled std. dev.  
2.215  standard error of difference  
0  hypothesized difference  
1.686  critical value  
6.299  t  
1.11E07  pvalue (onetailed, lower) 
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