The effect of choice on intentional and incidental memory

Recent studies have revealed that memory performance is better when participants have the opportunity to make a choice regarding the experimental task (choice condition) than when they do not have such a choice (fixed condition). These studies, however, used intentional memory tasks, leaving open the question whether the choice effect also applies to incidental memory. In the current study, we first repeated the choice effect on the 24-h delayed intentional memory performance (experiment 1). Next, using an incidental paradigm in which participants were asked to judge the category of the items instead of intentionally memorizing them, we observed the choice effect on judgment during encoding and memory performance in a 24-h delayed surprise test (experiment 2). Participants judged more accurately and quickly and had better recognition memory for items in the choice condition than for items in the fixed condition. These results are discussed in terms of the role of choice in both intentional and incidental memory.

Fractionating the reward-memory literature: Instructed, item-related feedback, and item-unrelated feedback

Over the last two decades, nearly one hundred studies have been published examining reward influences on memory. Implementations of reward-value procedures have varied markedly, as have other study characteristics, including images vs. words, intentional vs. incidental memory encoding, and recall vs. recognition tests. As such, the resulting state of the field has become unwieldy and somewhat difficult to identify consistent reward-memory effects from those that are inconsistent due to critical differences in the study methods. Here we provide an overview of these studies and fractionate their methods into three distinct procedures: instructed, item-related feedback, and item-unrelated feedback. Instructed studies tell participants of item-value associations during encoding with rewards earned during memory retrieval. In contrast, feedback studies ask participants to make responses during encoding, with rewards provided as feedback; memory retrieval itself is unrewarded. Some feedback studies require participants to make responses related to the to-be-remembered items, while others require participants to respond to an initial prompt before presenting an unrelated stimulus. While both procedures involve feedback, the first set of studies involves item-related feedback, and the second set has item-unrelated feedback. By fractionating the reward-memory literature into distinct procedures, an otherwise heterogenous mixture of study design characteristics becomes much more interpretable and the underlying cognitive mechanisms more clear. This additional clarity should improve predictions for future studies, as this framework helps identify which prior findings are more relevant, while also providing a summary of the current state of the field.

Thalamo-hippocampal pathway regulates incidental memory load: insights from sex differences

Memory can be challenged by increasing both its required duration and the amount of information to be encoded, namely the memory load. The dorsal hippocampus (dHP) has been involved in memory consolidation, which is the stabilization of a trace from short-term (STM) to long-term memory (LTM), as well as in the ability to process high information load. However, how memory load influences memory consolidation, and the underlying neural mechanisms, are yet unknown. To address this question, we used male and female mice that, despite having in our Different Object recognition Task (DOT) the same STM capacity of 6 objects, spontaneously show differences in the number of objects directly transferred to LTM, when tested over longer delays. Males memorize all 6 objects encoded, while females remember only up to 4, both at 1 and 24 h delays. Interestingly, males activate more the dHP (as measured by c-Fos expression), while females the thalamic nucleus reuniens (RE). Optogenetic inhibition of the RE-dHP pathway during off-line memory consolidation favors 6-object LTM retention in females by removing inhibitory control over dHP activation, while chemogenetic RE-activation impairs it in males. Our data represent a first demonstration of a sub-cortical control of dHP recruitment, that might underlie its sex-dependent activation during incidental memory, with potential also for clinical application.

EFFECT OF WITHIN-ITEM SOCIAL ELABORATION ON INCIDENTAL MEMORY

<p>The present study compared the effects of social and semantic elaboration on incidental memory. Two types of lists were provided to the participants: (1) a related list, in which a triplet of words had a common category name associated with each of them, and (2) an unrelated list, in which the three words did not have a common category name. Then, participants in the social elaboration condition generated a particular person’s name, and those in the semantic elaboration condition generated an association elicited by the three words. An unexpected free recall task followed. Results indicated higher recall of the related list in the social elaboration than in the semantic elaboration condition. In contrast, the unrelated list showed no difference between the two elaboration conditions. These results indicate that social elaboration functions as within-item elaboration, which is more effective than semantic elaboration.</p>

EFFECT OF WITHIN-ITEM SOCIAL ELABORATION ON INCIDENTAL MEMORY

<p>The present study compared the effects of social and semantic elaboration on incidental memory. Two types of lists were provided to the participants: (1) a related list, in which a triplet of words had a common category name associated with each of them, and (2) an unrelated list, in which the three words did not have a common category name. Then, participants in the social elaboration condition generated a particular person’s name, and those in the semantic elaboration condition generated an association elicited by the three words. An unexpected free recall task followed. Results indicated higher recall of the related list in the social elaboration than in the semantic elaboration condition. In contrast, the unrelated list showed no difference between the two elaboration conditions. These results indicate that social elaboration functions as within-item elaboration, which is more effective than semantic elaboration.</p>

Post-action memory enhancement: Exploring the temporal relationship between action and memory formation

Actions enhance incidental memory for items that appear in close succession. However, the role of action processes, such as preparation and execution, on the processes underlying such an interaction is unclear. Here, we examined the temporal dynamics of action-induced memory enhancement. In two experiments, participants performed Go/No-Go tasks while viewing task-unrelated pictures before or after their Go motor responses. Compared to items presented at similar time points in the No-Go trials, items presented after, not before, action execution were consistently better remembered in the subsequent memory tests. Our findings highlight the role of action execution and post-action processes, such as action-effect monitoring, in memory formation.

Get Your Guidance Going: Investigating the Activation of Spatial Priors for Efficient Search in Virtual Reality

Repeated search studies are a hallmark in the investigation of the interplay between memory and attention. Due to a usually employed averaging, a substantial decrease in response times occurring between the first and second search through the same search environment is rarely discussed. This search initiation effect is often the most dramatic decrease in search times in a series of sequential searches. The nature of this initial lack of search efficiency has thus far remained unexplored. We tested the hypothesis that the activation of spatial priors leads to this search efficiency profile. Before searching repeatedly through scenes in VR, participants either (1) previewed the scene, (2) saw an interrupted preview, or (3) started searching immediately. The search initiation effect was present in the latter condition but in neither of the preview conditions. Eye movement metrics revealed that the locus of this effect lies in search guidance instead of search initiation or decision time, and was beyond effects of object learning or incidental memory. Our study suggests that upon visual processing of an environment, a process of activating spatial priors to enable orientation is initiated, which takes a toll on search time at first, but once activated it can be used to guide subsequent searches.