No abstract

We like to thank Dries Trippas for providing his materials. We also thank André Aßfalg for technical support with the online data collection.Materials, participant data, and analysis scripts with complete output for all reported experiments can be found in the Open Science Framework archive https://osf.io/9avjc/.

For modeling recognition decisions in a typical eyewitness identification lineup task with multiple simultaneously presented test stimuli (also known as simultaneous detection and identification), essentially two different models based on signal detection theory are currently under consideration. These two models mainly differ with respect to their assumptions regarding the interplay between the memory signals of different stimuli presented in the same lineup. The independent observations model (IOM), on the one hand, assumes that the memory signal of each simultaneously presented test stimulus is separately assessed by the decision-maker, whereas the ensemble model (EM), on the other hand, assumes that each of these memory signals is first compared with and then assessed relative to its respective context (i.e., the memory signals of the other stimuli within the same lineup). Here, we discuss some reasons why comparing confidence ratings between trials with and without a dud (i.e., a lure with no systematic resemblance to the target) in an otherwise fair lineup—results of which have been interpreted as evidence in favor of the EM—is in fact inconclusive for differentiating between the EM and the IOM. However, the lack of diagnostic value hinges on the fact that in these experiments two aspects of between-item similarity (viz. old–new and within-lineup similarity) are perfectly confounded. Indeed, if separately manipulating old–new similarity, we demonstrate that EM and IOM make distinct predictions. Following this, we show that previously published data are inconsistent with the predictions made by the EM.

Recently, it has been suggested that the mnemonic information that underlies recognition decisions changes when participants are asked to indicate whether a test stimulus is new rather than old (Brainerd et al., 2021, Journal of Experimental Psychology: Learning Memory, and Cognition, advance online publication). However, some observations that have been interpreted as evidence for this assertion need not be due to mnemonic changes, but may instead be the result of conservative response strategies if the possibility of asymmetric receiver operating characteristics (ROCs) is taken into account. Conversely, recent findings in support of asymmetric ROCs rely on the assumption that the mnemonic information accessed by the decision-maker does not depend on whether an old or a new item is considered to be the target Kellen et al. (2021, Psychological Review 128[6], 1022–1050). Here, we aim to clarify whether there is such a difference in accessibility of mnemonic information by applying signal detection theory. To this end, we used two versions of a simultaneous detection and identification task in which we presented participants with two test stimuli at a time. In one version, the old item was the target; in the other, the new item was the target. This allowed us to assess differences in mnemonic information retrieved in the two tasks while taking possible ROC asymmetry into account. Results clearly indicate that there is indeed a difference in the accessibility of mnemonic information as postulated by (Brainerd et al., 2021, Journal of Experimental Psychology: Learning Memory, and Cognition, advance online publication).

In a recent study (Meyer-Grant & Klauer, 2022, Memory & Cognition, advance online publication), we reported results from a recognition memory experiment using a detection plus identification paradigm in which two items are simultaneously presented during each test trial. One of the key observations was an impairment of identification performance when new items instead of old items were defined as targets to be detected and identified. We have argued that this challenges the notion that the subjective mnemonic information underlying recognition decisions does not change depending on the status of the target being probed (i.e., on whether old or new items are considered targets), which is also known as the target-probe invariance assumption. As a side-effect of this finding, a critical test of ROC asymmetry conducted by Kellen et al. (2021, Psychological Review, 128[6], 1022--1050) is questioned inasmuch as a violation of target-probe invariance provides an alternative interpretation of effects observed with this test. In response to this, Kellen and Singmann (2022, unpublished manuscript) suggest an alternative explanation of our findings in terms of an occasional guessing process. If true, this would allow one to retain the target-probe invariance assumption and in consequence, Kellen et al.'s interpretation of their results as evidence in favor of ROC asymmetry. Kellen and Singmann also review other pieces of evidence for ROC asymmetry in the context of recognition memory. Here, we discuss limitations of these pieces of evidence, highlighting the need for additional evidence such as provided by Kellen et al.'s critical test. We also point out that merely proposing an alternative explanation is not yet sufficient to invalidate our concerns about this critical test. To enable a more conclusive resolution of this issue, we conducted further analyses of our previously published data and a new experiment. Overall, the results indicate that identification responses in our original study may indeed have been contaminated by occasional guessing, thus rehabilitating the target-probe invariance assumption as well as Kellen et al.'s critical test of ROC asymmetry.