Date of Award

1998

Degree Type

Thesis

Degree Name

Bachelor of Arts Honours

School

School of Psychology

Faculty

Faculty of Health and Human Sciences

First Advisor

Dr Susan Gee

Abstract

Evidence regarding the potential mediating effects sequential test presentation has upon eyewitness suggestibility is divided. Bekerian and Bowers' (1983) research suggested that sequential test presentation reduced misinformation effects, whilst McCloskey and Zaragoza's (1985) results failed to indicate any effect of this presentation method. A possible reason for these conflicting results is that the respective research groups have used different sets of slides. Bekerian and Bowers' (1983) slides appeared to contain more thematic content (i.e., linear content), which in turn increased participants' resistance to misleading postevent information. Conversely, McCloskey and Zaragoza's (1985) slides appeared to lack this feature (i.e., they are non linear). Therefore, it was suggested that the influence that sequential testing had upon misinformation effects was mediated by the amount of linear content present amongst the slides used by the previous researchers. The present study was designed to evaluate this hypothesis. One hundred and twelve participants were assigned to one of four conditions, which involved a combination of two critical manipulations: the degree of linearity present in slides (linear vs. non linear) and test presentation order (sequential vs. random). To simulate a misinformation effect, participants were exposed to both consistent (control) and inconsistent (misled) postevent items. The dependent variable involved participant's recognition difference performance, which was created by subtracting participants' misled item performance scores from their control item performance scores. One sample l tests were then used to compare each of the four cells recognition difference scores. Any scores which were significantly higher than zero were interpreted as being indicative of a misinformation effect. All four of the cells' recognition difference scores were in the direction consistent with a misinformation effect (i.e., a positive score). However, only one of the cells (i.e., the linear-sequential cell) reported a significant misinformation effect. In the other three cells, the recognition difference scores were not significantly higher than zero, although the non linear-random cell test result was only marginally non significant. This pattern of results was inconsistent with the experimental hypothesis. Had this been supported, the two non linear cells would also have displayed misinformation effects. Furthermore, results failed to confirm McCloskey and Zaragoza's ( 1983) predictions that all four of the cells would experience misinformation effects, regardless of test presentation. The misinformation effect detected in the linear-random cell, and the trend toward such an effect found in the non linear-random cell suggested that the influence sequential testing had upon misinformation effects was independent of slide linearity. This pattern of results was consistent with Bekerian and Bowers' (1983) hypothesis. The implications and validity of these results are discussed.

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