Date of Award

Spring 5-16-2019

Document Type


Degree Name

Master of Arts (MA)


Forensic Psychology



First Advisor

Steven Penrod

Second Reader

Margaret Kovera

Third Advisor

Kelly McWilliams


Similarity and confidence are often analyzed in relation to eyewitness accuracy. Duds, highly dissimilar fillers, can impact an eyewitness’ accuracy and confidence. This study analyzed the impact of duds, similarity and accuracy in the context of lineup bias. This study found that in target-absent conditions there is a significant positive relationship between lineup bias and confidence. This study also found that highly similar lineups results in a lower proportion of correct identification, even in highly confident witnesses, compared to medium similar and low similar lineups. Further research should look closer at the “sweet spot” of similarity in order to advise and put in place proper similarity scores when picking fillers in lineups.



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