Comparing witness performance in the field versus the lab: How real-world conditions affect eyewitness decision-making.

Abstract

Objective: This field-simulation experiment was designed to compare eyewitness performance when conducting show ups and lineups under field versus laboratory conditions. Hypotheses: We expected to replicate the findings from previous field-simulation experiments showing overconfidence in show up identifications made under field but not lab conditions, and further predicted that under field conditions, high-confidence identifications are more likely to be correct when using lineups compared with show ups. It was also expected that field conditions would lead witnesses to lower their criterion for choosing with show ups, but we did not know how field conditions would affect lineup decision-making. Method: Participants (N = 719) witnessed the theft of a laptop computer and were asked to identify a suspect from a live show up, a photographic show up, or a photographic lineup administered under either field or lab conditions. In the field condition, uniformed officers functioned as experimenters and participants were immersed in what they were led to believe was an actual police investigation. In the lab condition, participants were debriefed before the identification procedure that the theft was staged for research purposes and that their identifications were being made as part of a study on eyewitness memory. Results: As predicted, witnesses were overconfident in their show up identifications made under field but not lab conditions, and high-confidence identifications were more likely to be correct when using lineups compared with show ups. Also as expected, field conditions led witnesses to lower their criterion for choosing with show ups regardless of culprit presence. However, the opposite was true for lineups, such that field conditions resulted in witnesses raising their criterion for choosing. Conclusions: Field conditions had a very different effect on witness performance when conducting show ups compared with lineups. When witnesses were led to believe that their identification would result in the arrest and prosecution of the suspect, they became more liberal in their decision-making when show ups were used but more conservative when lineups were employed. Public Significance StatementThis study examined how real-world conditions affect eyewitnesses beyond what can be assessed in a lab study. This was accomplished by comparing eyewitnesses' performance when they knew they were participating in research to their performance under field conditions, in which their identification would presumably result in the arrest of the suspect. Results demonstrated that many important findings from previous lab studies generalized well to field conditions, but also revealed that the situational pressures of being a witness in an actual police investigation can affect eyewitness performance differently depending on the procedures used to obtain the identification.

The rule out procedure: A signal-detection-informed approach to the collection of eyewitness identification evidence.

“…Clearly it is time to move on from this deeply flawed identification procedure. In fact, contrary to consensus among psychological scientists and legal scholars, we also demonstrated that the showup procedure better discriminates guilty suspects from innocent suspects than does the standard simultaneous lineup (Eisen et al, 2022; Starns et al, 2021). Given the inherent risk that a showup poses to a potentially innocent suspect, many will find that evidence unsettling.…”

“…For showups, suspect identifications made with 100% confidence were correct 89% of the time, but identifications made with lower levels of confidence were far less accurate. These patterns largely replicate past research (e.g., Eisen et al, 2022; Sauerland et al, 2018; Wixted & Wells, 2017). For suspect identifications, the yield reflects the total proportion of culprit-present conditions leading to a particular outcome.…”

“…According to the MAX signal detection model (see Figure 2), lineup rejections often scale match to memory for a filler rather than for the suspect, which undermines the potential for lineups to rule out innocent suspects. Fillers were so detrimental to the rule out potential of lineups that lineups had worse discriminability than did showups (see Figure 4; Eisen et al, 2022; Starns et al, 2021). This pattern demonstrates that lineups are not objectively superior to showups and reinforces recent calls to consider all identification outcomes when making inferences about which of two identification procedures is superior (Smith et al, 2020; Starns et al, 2021).…”

“…Yet, more recent research focusing on both the potential to rule in guilty suspects and on the potential to rule out innocent suspects finds that showups are better at ruling out innocent suspects than are lineups (they have a better trade-off for correct rejections and misses). In fact, showups are so much more effective at ruling out innocent suspects that they have better overall discriminability than do lineups (Eisen et al, 2022; Starns et al, 2021). This creates a serious dilemma.…”

Estimation of eyewitness error rates in fair and biased lineups.

“…The experiments were completed online in a single session lasting 5–10 min. Participants also knew that the crime they witnessed was staged, which can affect lineup decisions (Eisen et al, 2022). Although such experiments are useful for understanding relative differences in the risk to an innocent suspect (Wells & Quinlivan, 2009), greater ecological validity would be necessary before extrapolating the precise error rates observed to real criminal cases.…”