(20)  For the following examples, please list the IV(s) and the DV(s) and select the best description of the design employed.  All examples are based on psychology journal abstracts.

The purpose of the present study was to extend research on repetition and illusory truth to the domain of eyewitness suggestibility.  Specifically, we assessed whether repeated exposure to suggestion, relative to a single exposure, facilitates the creation of false memory for suggested events.  After viewing a video of a burglary, subjects were asked questions containing misleading suggestions.  Some subjects heard the suggestions once, some three times.  Their memory for the source of the suggestions was tested.  The results showed that following repeated exposure to suggestion, subjects were more likely to claim that they remembered the source of the suggested events as being the video.   Zaragoza & Mitchell (1996) Psychological Science, 7, 294-300.



 DESIGN (Selected from below):  ________

To explore the forensic implications of ‘verbal overshadowing’ in young and older eyewitnesses, we examined the effects of providing a verbal description on subsequent performance in a lineup task.  Young (18-30 years) and older (60-80 years) adults viewed a videotaped crime and performed some unrelated cognitive tasks.  Participants were then asked to supply a description of the target person in the event or to perform an unrelated control task.  Upon completing the description/control task, participants attempted to identify the target person from a target present photo lineup.  Older participants made more false choices.  There was a weak trend consistent with verbal overshadowing such that providing a verbal description reduced performance slightly.  Memon & Bartlett (2002).  Applied Cognitive Psychology, 16, 635-650.



 DESIGN (Selected from below):  ________

a.  Basic two group between-subjects experiment
b.  Basic within-subjects with two levels
c.  Basic status variable with two groups
d.  One multiple level between-subjects IV
e.  One multiple level within-subjects IV
f.  One multiple level status variable
g.  factorial design: 2 between-subjects variables
h.  factorial design: 2 status variables
i.  factorial design: 2 within-subjects variables
j.  factorial design: 1 status; 1 between
k.  factorial design: 1 between; 1 within
l.  factorial design: 1 status; 1 within

(10)  For the following sets of descriptive summaries, predict whether a t-test would obtain a probability of less than .05.  Explain your predictions using the rule of thumb.

                                      Group A               Group B
 Mean                                546.67                433.98
 Standard Deviation           121.56                 107.32
 N                                       35                         28

                                           Group A             Group B
 Mean                                     0.25                    1.82
 Standard Deviation                1.56                     1.61
 N                                           13                         16

(20) Based on the following information, please find the probability level associated with the t statistic and write a results paragraph.

Subjects are shown a videotape.  They are then given post-event misleading information (10 pieces).  The information is presented in a narrative that purports to describe the video they saw.  One group of subjects is given each piece of misleading information one time, whereas another group is given each piece of misleading information 5 times.  They finally take a memory test that includes questions for each piece of misleading information.

Design:  a between-subjects IV with two levels
IV:  number of repetitions of misleading information; one vs. five
DV:  Number of incorrect pieces of information a subject incorporates into a memory of videotape viewed (out of a possible 10)
Ss:  50 first-year college students randomly assigned to the conditions (25 per condition)

                                                                         # of incorrect pieces of information remembered
# of repetitions of missinformation                                     Mean                   Standard Dev
 one                                                                                 2.17                           2.98
 five                                                                                 5.43                           3.14

t = - 3.765

(10)  What is a confound?  Please explain how a confound impacts a researcher’s ability to draw conclusions about the outcome of an experiment.

(10)  When computing a hypothesis testing statistic, does a researcher prefer large or small variability?  Please explain why.