Presumed-Blind Lineup Administrators Can Influence Eyewitnesses’ Identification Decisions and Confidence

An overlooked observation in the literature on double-blind lineups is that double-blind lineup administrators sometimes engage in behaviors that could influence eyewitnesses. We tested whether such administrator behaviors influence eyewitnesses’ identification decisions and confidence when eyewitnesses are explicitly instructed that the administrator does not know which lineup member is the suspect, as is recommended as a matter of best practice. Mock-eyewitnesses were paired with a lineup administrator who was a confederate of the research team and who administered a culprit-absent lineup to the eyewitnesses. During the lineup, the administrator provided ostensibly spontaneous behavioral feedback to eyewitnesses of the sort that has been found to sometimes occur in double-blind lineups (e.g., “It seems like you keep coming back to Number 2”) or gave no such behavioral feedback. In a preliminary experiment (N = 77), we secured identifications from all eyewitnesses to assess the effects of behavioral feedback on lineup preferences among identifying witnesses. In the second experiment (N = 238), witnesses could reject the lineup and were again randomly assigned to receive behavioral feedback or no feedback during the lineup. After eyewitnesses made a lineup decision, they reported their confidence and provided other testimony-relevant judgments. Even though witnesses knew that the lineup administrator had no knowledge of which lineup member was the suspect, behavioral feedback from the lineup administrator influenced eyewitnesses’ identification decisions and confidence. These findings provide proof-of-concept that eyewitness evidence collected in double-blind lineups can be contaminated by administrator influence.