Ranking Tasks in Recognition Memory: A Direct Test of the Two-High-Threshold Contrast Model

It has long been debated whether latent memory strength determines recognition judgments directly, or through a small number of discrete states. Often, signal detection theory (SDT) models instantiate the former perspective, whereas the two-high-threshold (2HT) model instantiates the latter. Kellen and Klauer (2014) conducted a critical test using a ranking paradigm that yielded results in line with common SDT models and incompatible with the 2HT model. However, Malejka et al. (2022) recently challenged their conclusion. They argued that the 2HT model can account for the critical effect if detection probabilities were determined by a memory strength contrast between simultaneously presented stimuli. Here, we test this contrast mechanism directly. We show that when only a single old item is presented, such a contrast mechanism entails a decrease in the probability of correctly rejecting the accompanying new items as their number increases. SDT models, on the other hand, predict the opposite pattern. Results of an empirical investigation were in agreement with SDT and inconsistent with the 2HT contrast model. Thus, our findings strengthen the conclusions of Kellen and Klauer (2014) and provide further evidence for SDT models of recognition memory.