Diagnosing eyewitness identifications with reaction time-based concealed information test: the effect of observation time

Abstract

Eyewitness identification procedures rely heavily on explicit identification from lineups. Lineups have been criticized because they have a considerable error rate. We tested the potential of implicit identifications in a Concealed Information Test (CIT) as an alternative. Previous experiments have suggested that implicit identification procedures might be suited when viewing conditions were favorable. In two experiments, mock eyewitnesses (Ns = 94, 509) witnessed a videotaped mock theft with longer or shorter observation time. We derived eyewitness identifications either implicitly from CIT reaction times or explicitly from simultaneous photo lineups. In Experiment 2, we also manipulated perpetrator presence. In both experiments, the perpetrator-present CIT showed capacity to diagnose face recognition, with large effect sizes (dE1 = 0.85 [0.51; 1.18]; dE2 = 0.74 [0.52; 0.96]), as expected. Unexpectedly, no moderation by observation time was found. In line with our hypothesis, no CIT effect emerged in the perpetrator-absent condition, indicating the absence of recognition (dE2 = 0.02 [− 0.17; 0.20]). We found no compelling evidence that one method would outperform the other. This work adds to accumulating evidence that suggests that, under favorable viewing conditions and replication provided, the RT-CIT might be diagnostic of facial recognition, for example when witnesses are hesitant of making an explicit identification. Future work might investigate conditions that affect performance in one, but not the other identification method.

Diagnosing eyewitness identifications with reaction time‑based Concealed Information Test: the effect of viewpoint congruency between test and encoding

“…In our first comparison (Experiment 1 vs. 2), performance in the RT-CIT and lineups was largely equivalent, but in our second comparison (Experiment 3 vs. 4), lineups clearly outperformed RT-CIT. Two previous experiments that compared RT-CIT and lineup performance were inconclusive (Sauerland et al, 2023 ): some Bayes factors supported the idea that the two procedures were equivalent, some that lineups were superior, and some that RT-CIT was superior. Combined with the current findings, we can only conclude that compelling or consistent evidence for the superiority of one method over the other is still lacking.…”

“…It is also conceivable that encoding conditions differentially affect the two identification procedures. Indeed, in another comparison between RT-CIT and lineups, observation time did not moderate the CIT effect across two experiments, whereas it did moderate the CIT effect in probe-absent lineups in one experiment (Sauerland et al, 2023 ).…”

“…One issue of interest is that the CIT effects we observed here – similar to other experiments that tested the validity of the RT-CIT for diagnosing face recognition – was below the average effect size commonly found in RT-CIT experiments (i.e., d = 1.04 in a meta-analysis, Suchotzki et al, 2017 ; cf. Sauerland et al, 2023 ). Those strong effects in memory detection likely derive from the high self-relevance of the probes and the combination of several stimulus groups in one CIT protocol (e.g., sites of crime, identity of accomplices).…”

“…Yet, the electrophysiological index of recognition may have been the result of the simultaneous explicit identification. In recent, stricter applications of the CIT protocol in a typical eyewitness paradigm, the RT-CIT showed a good capacity to differentiate the stimulus film actors (i.e., probes) from irrelevants in three experiments ( d = 1.21; Georgiadou et al, 2019 , Experiment 2b; d s = 0.85 and 0.74; Sauerland et al, 2023 ) and moderate capacity in another ( d = 0.39; Sauerland et al, 2019 , Experiment 4). Additionally, one experiment included a probe-absent CIT condition and demonstrated a good capacity of the CIT to differentiate between guilty and innocent suspects (Sauerland et al, 2023 , Experiment 2).…”

“…These conflicting findings within facial recognition RT-CIT experiments might originate from differences in encoding conditions and event complexity. Experiments with moderate to large effects included only two rather than four actors and provided ample close-ups of both (Georgiadou et al, 2019 , Experiment 2b; Sauerland et al, 2019 , Experiment 4, Sauerland et al, 2023 ). In the experiment with the largest effect size (Georgiadou et al, 2019 , Experiment 2b), encoding was additionally enhanced by presenting the pictures of the actors for 15 s after participants had viewed the stimulus film and prior to taking the RT-CIT.…”