Modeling the dynamics of recognition memory testing

A robust finding in recognition memory is the observation that performance declines monotonically across test trials. Despite the prevalence of this result, there is a lack of consensus on the mechanism responsible for the decline. Three hypotheses have been put forward: 1. ) interference is caused by the learning of test items 2. ) the test items cause a shift in the context representation used to cue memory and 3. ) participants change their speed-accuracy thresholds through the course of testing. We implemented all three possibilities in a combined model of recognition memory and decision making, which inherits the memory retrieval elements of the Osth and Dennis (2015) model and uses the diffusion decision model (DDM: Ratcliff, 1978) to generate choice and response times. We applied the model to four datasets that represent three challenges in the literature on testing effects in recognition memory: 1. ) the finding that the number of test items plays a larger role in determining performance than the number of studied items, 2. ) the finding that performance decreases less for strong items than weak items in pure lists but not in mixed lists, and 3. ) the finding that lexical decision trials interspersed between recognition test trials do not impact performance. Analysis of the resulting parameter estimates suggests that item interference plays a very weak role in explaining the effects of recognition testing, while context drift plays a very large role. Changes in speed-accuracy thresholds did not show a consistent tendency either upward or downward, but were demonstrated to show a very large role in moderating the size of the testing effect. These results are consistent with prior work showing a weak role for item noise in recognition memory and other results demonstrating that retrieval is a strong cause of context change in episodic memory. DYNAMICS OF RECOGNITION TESTING 3 Modeling the dynamics of recognition memory testing A major constraint on models of memory concerns how the number of items present in memory affects memory performance. Such manipulations of memory set size have constrained models of recognition memory at both short (Nosofsky, Little, Donkin, & Fific, 2011; Sternberg, 1966; McElree & Dosher, 1989) and long (Clark & Gronlund, 1996; Dennis & Humphreys, 2001; Gillund & Shiffrin, 1984; McClelland & Chappell, 1998; Osth & Dennis, 2015; Shiffrin & Steyvers, 1997) time scales. Much theoretical interest concerns how the number of studied items in memory affects performance. However, of recent focus in recognition memory research is how the number of tested items affects memory. A nearly universal finding in recognition memory research is that recognition memory performance decreases through the course of testing, with later test trials performing more poorly than earlier test trials. This finding was first reported by Peixotto (1947) but has been replicated extensively in the many decades since its original publication (Annis, Malmberg, Criss, & Shiffrin, 2013; Averell, Prince, & Heathcote, 2016; Criss, Malmberg, & Shiffrin, 2011; Kiliç, Criss, Malmberg, & Shiffrin, 2017; Kim & Glanzer, 1995; Malmberg, Criss, Gangwani, & Shiffrin, 2012; Murdock & Anderson, 1975; Ratcliff & Hockley, 1980; Schulman, 1974; Shiffrin, Huber, & Marinelli, 1995). However, despite its status as an empirical regularity, theoretical interest in the nature of the testing effect has emerged somewhat more recently (e.g.: Criss et al., 2011; Osth & Dennis, 2015). The finding has been referred to as "output interference" in some parts of the literature. We will instead be referring to the finding as the test position effect, or TPE, to avoid commitment to the idea that the effect is driven by interference. Modeling of the TPE has explored causal factors acting through the decision process or memory retrieval, but not both. This work aims to bridge that gap by introducing a new combined model of memory retrieval and decision making. DYNAMICS OF RECOGNITION TESTING 4