Modeling the continuous recognition paradigm to determine how retrieval can impact subsequent retrievals.

There are several ways in which retrieval during a memory test can harm memory: (a) retrieval can cause an increase in interference due to the storage of additional information (i.e., item-noise); (b) retrieval can decrease accessibility to studied items due to context drift; and (c) retrieval can result in a trade in accuracy for speed as testing progresses. While these mechanisms produce similar outcomes in a study-test paradigm, they are dissociated in the 'continuous' recognition paradigm, where items are presented continuously and a participant's task is to detect a repeat of an item. In this paradigm, context drift results in worse performance with increasing study-test lag (the lag effect), whereas increasing item-noise is evident in a decrease in performance for later test trials in the sequence (the test position effect [TPE]). In the present investigation, we measured the influences of item-noise, context drift, and decision-related factors in a novel continuous recognition dataset using variants of the Osth et al. (2018) global matching model. We fit both choice and response times at the single trial level using state-of-the-art hierarchical Bayesian methods while incorporating crucial amendments to the modeling framework, including multiple context scales and sequential effects. We found that item-noise was responsible for producing the TPE, context drift decreased the magnitude of the TPE (by diminishing the impact of item-noise), and speed-accuracy changes had some minor effects that varied across participants.

A yeast cell cycle pulse generator model shows consistency with multiple oscillatory and checkpoint mutant datasets.

Modeling biological systems holds great promise for speeding up the rate of discovery in systems biology by predicting experimental outcomes and suggesting targeted interventions. However, this process is dogged by an identifiability issue, in which network models and their parameters are not sufficiently constrained by coarse and noisy data to ensure unique solutions. In this work, we evaluated the capability of a simplified yeast cell-cycle network model to reproduce multiple observed transcriptomic behaviors under genomic mutations. We matched time-series data from both cycling and checkpoint arrested cells to model predictions using an asynchronous multi-level Boolean approach. We showed that this single network model, despite its simplicity, is capable of exhibiting dynamical behavior similar to the datasets in most cases, and we demonstrated the drop in severity of the identifiability issue that results from matching multiple datasets.

Does source memory exist for unrecognized items?

In episodic memory research, there is a debate concerning whether decision-making in item recognition and source memory is better explained by models that assume all-or-none retrieval processes or continuous underlying strengths. One aspect in which these classes of models tend to differ is their predictions regarding the ability to retrieve contextual details (or source details) of an experienced event, given that the event itself is not recognized. All-or-none or high-threshold models predict that when items are unrecognized, source retrieval is not possible and only guess responses can be elicited. In contrast, models assuming continuous strengths predict that it is possible to retrieve the source of unrecognized items, albeit with low accuracy. Empirically, there have been numerous studies reporting either chance accuracy or above-chance accuracy for source memory in the absence of recognition. Crucially, studies presenting recognition and source judgements for the same item in immediate succession (simultaneous design) have revealed chance-level accuracy, while studies presenting a block of recognition judgements followed by a block of source judgements (blocked design) have revealed slightly above-chance accuracy. Across three sets of experiments involving multiple design manipulations, the present investigation demonstrated: (a) that source memory for unrecognized items is indeed higher in blocked designs; (b) that evidence for the effect in blocked designs is likely artifactual due to item memory changing between blocks; and (c) that the effect does exist in simultaneous designs, but is highly subtle and is more easily detected when uncertainty in the participant-level data is low or is accounted for in a hierarchical Bayesian model. It is suggested that findings of a null effect in the prior literature may be attributable to design elements that hinder source memory as a whole, and to high degrees of uncertainty in the participant-level source data when conditioned on unrecognized items. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Are associations formed across pairs? A test of learning by temporal contiguity in associative recognition.

In models such as the search of associative memory (SAM: Gillund & Shiffrin, Psychological Review, 91(1), 1-67 1984) model, associations in paired-associate tasks are only formed between the pair of to-be-remembered items. The temporal context model (TCM: Howard & Kahana, Journal of Mathematical Psychology, 46, 268-299 2002) deviates from SAM by positing that long-range associations are formed between the current item and all previously presented items, even in paired-associate tasks, where cross-pair associations are formed in addition to within-pair associations (Davis, Geller, Rizzuto, & Kahana, Psychonomic Bulletin & Review, 15, 64-69 2008). We tested this proposal in an associative recognition task by constructing rearranged pairs where the distance in within-list serial position between the two pair members was manipulated between one and five pairs. Models such as TCM would predict that FAR should be highest for rearranged pairs that are constructed from pair members that were adjacent to each other on the study list, whereas models such as SAM predict that FAR should be equal for rearranged pairs regardless of whether they are constructed from adjacent or remote pairs. Results from our experiment and from three archival datasets found that FAR for rearranged pairs did not depend on whether the constituent items came from nearby or remote pairs, suggesting that participants were not forming associations across pairs of items in the task.