Showups versus lineups: An evaluation using ROC analysis ⿿

Showups (a one-person identification) were compared to both simultaneous and sequential lineups that varied in lineup fairness and the position of the suspect in the lineup. We reanalyzed data from a study by Gronlund, Carlson, Dailey, and Goodsell (2009), which included simultaneous and sequential lineups, and using the same stimuli and procedures, collected new data using showup identifications. Performance was compared using ROC analysis, which is superior to traditional measures such as correct and false identification rates, and probative value measures. ROC analysis showed that simultaneous lineups consistently produced more accurate identification evidence than showups, but sequential lineups were sometimes no more accurate than showups, and were never more accurate than simultaneous lineups. These results supported prior suppositions regarding the suggestiveness of showups, revealed a misconception about the superiority of sequential lineups, and demonstrated why eyewitness identification procedures need to be evaluated using ROC analyses.

⿺ We used ROC analysis to compare showups to simultaneous and sequential lineups. ⿺ Showups are less diagnostic than simultaneous lineups. ⿺ For early suspect position, sequential lineup performance is equivalent to showup performance. ⿺ For late suspect position, sequential lineup performance is equivalent to simultaneous lineup performance. ⿺ Sequential lineups are not diagnostically superior to simultaneous lineups.