Implicit Memory and Anesthesia: A Systematic Review and Meta-Analysis

General anesthesia should induce unconsciousness and provide amnesia. Amnesia refers to the absence of explicit and implicit memories. Unlike explicit memory, implicit memory is not consciously recalled, and it can affect behavior/performance at a later time. The impact of general anesthesia in preventing implicit memory formation is not well-established. We performed a systematic review with meta-analysis of studies reporting implicit memory occurrence in adult patients after deep sedation (Observer’s Assessment of Alertness/Sedation of 0–1 with spontaneous breathing) or general anesthesia. We also evaluated the impact of different anesthetic/analgesic regimens and the time point of auditory task delivery on implicit memory formation. The meta-analysis included the estimation of odds ratios (ORs) and 95% confidence intervals (CIs). We included a total of 61 studies with 3906 patients and 119 different cohorts. For 43 cohorts (36.1%), implicit memory events were reported. The American Society of Anesthesiologists (ASA) physical status III–IV was associated with a higher likelihood of implicit memory formation (OR:3.48; 95%CI:1.18–10.25, p < 0.05) than ASA physical status I–II. Further, there was a lower likelihood of implicit memory formation for deep sedation cases, compared to general anesthesia (OR:0.10; 95%CI:0.01–0.76, p < 0.05) and for patients receiving premedication with benzodiazepines compared to not premedicated patients before general anesthesia (OR:0.35; 95%CI:0.13–0.93, p = 0.05).

An Implicit Memory-Based Method for Supervised Pattern Recognition

How the human brain does recognition is still an open question. No physical or biological experiment can fully reveal this process. Psychological evidence is more about describing phenomena and laws than explaining the physiological processes behind them. The need for interpretability is well recognized. This paper proposes a new method for supervised pattern recognition based on the working pattern of implicit memory. The artificial neural network (ANN) is trained to simulate implicit memory. When an input vector is not in the training set, the ANN can treat the input as a “do not care” term. The ANN may output any value when the input is a “do not care” term since the training process needs to use as few neurons as possible. The trained ANN can be expressed as a function to design a pattern recognition algorithm. Using the Mixed National Institute of Standards and Technology database, the experiments show the efficiency of the pattern recognition method.

STOP SHOUTING AT ME: The Influence of Case and Self-Referencing on Explicit and Implicit Memory

Evidence suggests that physical changes in word appearance, such as those written in all capital letters, and the use of effective encoding strategies, such as self-referential processing, improves memory. In this study we examined the extent both physical changes in word appearance (case) and encoding strategies engaged at study influence memory as measured by both explicit and implicit memory measures. Participants studied words written in upper and lower case under three encoding conditions (self-reference, semantic control, case judgment), which was followed by an implicit (word stem completion) and then an explicit (item and context) memory test. There were two primary results. First, analyses indicated a case enhancement effect for item memory where words written in upper case were better remembered than lower case, but only when participants were prompted to attend to the case of the word. Importantly, this case enhancement effect came at a cost to context memory for words written in upper case. Second, self-referencing increased explicit memory performance relative to control, but there was no effect on implicit memory. Overall, results suggest an item-context memory trade-off for words written in upper case, highlighting a potential downside to writing in all capital letters, and further, that both physical changes to the appearance of words and differing encoding strategies have a strong influence on explicit, but not implicit memory.

The N400 ERP component reflects a learning signal during language comprehension

The functional significance of the N400 ERP component is still actively debated. Based on neural network modeling it was recently proposed that the N400 component can be interpreted as the change in a probabilistic representation corresponding to an internal temporal-difference prediction error at the level of meaning that drives adaptation in language processing. These computational modeling results imply that increased N400 amplitudes should correspond to greater adaptation. To investigate this model derived hypothesis, the current study manipulated expectancy in a sentence reading task, which influenced N400 amplitudes, and critically also later implicit memory for the manipulated word: reaction times in a perceptual identification task were significantly faster for previously unexpected words. Additionally, it could be demonstrated that this adaptation seems to specifically depend on the process underlying N400 amplitudes, as participants with larger N400 differences also exhibited a larger implicit memory benefit. These findings support the interpretation of the N400 as an implicit learning signal in language processing.

Applying Self-Coding to the Measurement of Self-Generated Video Gaming and Gambling Memory Associations

Recently the use of implicit memory associations has expanded in the addiction literature to include the assessment of video gaming and gambling. However, the issue with memory associations lies in the open-ended nature of the answers that must be coded, which is often labour-intensive, costly, and where the ambiguity cannot always be resolved. The present study evaluates participant self-coding of memory associations versus researcher coding in the assessment of memory associations for video gaming and gambling. A sample of 3,176 Canadian adults were asked to produce responses to ten ambiguous words and ten potential behavioural associations for engagement in video gaming or gambling. Participants were subsequently asked to classify what categories their responses belonged to, including video gaming and gambling. Consistent with the literature on alcohol and marijuana memory associations, self-coded scores for video gaming and gambling were significantly higher than scores coded by the researchers, had significantly higher correlations with self-reported behaviours, and significantly improved the prediction of video gaming and gambling behaviours.Résumé L’utilisation des associations de la mémoire implicite comprend depuis peu l’évaluation des jeux vidéo et des jeux de hasard dans le vocabulaire de la dépendance. Le problème des associations de la mémoire réside toutefois dans le caractère ouvert des réponses qui doivent être codées, ce qui est souvent à haute intensité de main-d’œuvre et coûteux. De plus, il est parfois impossible de résoudre l’ambiguïté. La présente étude évalue l’autocodage par les participants des associations de la mémoire par rapport au codage effectué par le chercheur dans le cadre des jeux vidéo et des jeux de hasard. On a demandé à un échantillon de 3 176 Canadiens d’âge adulte de répondre à dix mots ambigus et dix associations comportementales potentielles en rapport avec la participation à des jeux vidéo ou des jeux de hasard. On leur a ensuite demandé de classer leurs réponses dans différentes catégories, y compris les jeux vidéo et les jeux de hasard. Tout comme dans la documentation sur les associations de mémoire dans le domaine de l’alcool et de la marijuana, les pointages autocodés pour les jeux vidéo et les jeux de hasard étaient considérablement plus élevés que ceux codés par les chercheurs, faisaient l’objet d’une corrélation beaucoup plus élevée avec des comportements autodéclarés, et amélioraient considérablement la prédiction de comportements liés aux jeux vidéo et aux jeux de hasard.

Sex Does Not Sell: Effects of Sexual Advertising Parameters on Women Viewers’ Implicit and Explicit Recall of Ads and Brands

This study investigated implicit and explicit memory effects of sexual and non-sexual advertisements embedded in either a sexual or non-sexual program among women viewers. We predicted that sexual appeals would facilitate implicit memory for the brand, and we explored whether program-type (sexual or non-sexual) and its associated congruity would impact or moderate recall of the surrounding advertisement among a small sample (n = 52) of exclusively women advertisement viewers. Sexual (versus non-sexual) advertising led to significantly worse implicit memory for the brand logo but better explicit recall for the advertisement scene itself. There was no effect of sexual appeals on explicit brand name recall, and no significant effect on advertisement recall of the program type. There was a significant interaction effect for program type and advertisement type for explicit recall of the advertisement scene, in which program-type moderated sexual advertisement recall. These results suggest that sexual advertising may increase memory for the advertisement at the expense of recalling the brand advertised. Limitations and implications of this study are discussed.