Lineup fairness: propitious heterogeneity and the diagnostic feature-detection hypothesis

Curt A Carlson,Jane E Whittington,Alyssa R Jones,Alex R Wooten,Maria A Carlson,Robert F Lockamyeir

doi:10.1186/s41235-019-0172-5

Curt A Carlson, Jane E Whittington + Show 4 more

Open Access

https://doi.org/10.1186/s41235-019-0172-5

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Abstract

Researchers have argued that simultaneous lineups should follow the principle of propitious heterogeneity, based on the idea that if the fillers are too similar to the perpetrator even an eyewitness with a good memory could fail to correctly identify him. A similar prediction can be derived from the diagnostic feature-detection (DFD) hypothesis, such that discriminability will decrease if too few features are present that can distinguish between innocent and guilty suspects. Our first experiment tested these predictions by controlling similarity with artificial faces, and our second experiment utilized a more ecologically valid eyewitness identification paradigm. Our results support propitious heterogeneity and the DFD hypothesis by showing that: 1) as the facial features in lineups become increasingly homogenous, empirical discriminability decreases; and 2) lineups with description-matched fillers generally yield higher empirical discriminability than those with suspect-matched fillers.

Highlights

Mistaken eyewitness identification (ID) remains the primary contributing factor to the over 350 false convictions revealed by DNA exonerations (Innocence Project, 2019), and is a factor in 29% of the over 2200 exonerations nationally (National Registry of Exonerations, 2018)
In order to be comparable to the correct ID rates of targets from TP lineups, the total number of false IDs from TA lineups were divided by the number of lineup members (6) to calculate false ID rates, which is a common approach in the literature when there is no designated innocent suspect (e.g., Mickes, 2015)
It is unlikely that a large number of police departments construct highly biased lineups, as most report that they select fillers by matching to the suspect (Police Executive Research Forum, 2013)

Summary

Introduction

Mistaken eyewitness identification (ID) remains the primary contributing factor to the over 350 false convictions revealed by DNA exonerations (Innocence Project, 2019), and is a factor in 29% of the over 2200 exonerations nationally (National Registry of Exonerations, 2018). Lindsay and Wells (1980) found that using fillers that matched the perpetrator’s description, as opposed to matching the suspect, reduced false IDs more than correct IDs (see Luus & Wells, 1991). They concluded that eyewitness ID accuracy is best if the fillers do not match the suspect too poorly (see Lindsay & Pozzulo, 1999) and do not match the suspect too well, as they can when matched to the suspect rather than description of the perpetrator

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