Implicit Memory Measures Research Articles

The role of linguistic factors in the retention of verbatim information in reading: An eye-tracking study on L1 and L2 German

AbstractWe investigated the retention of surface linguistic information during reading using eye-tracking. Departing from a research tradition that examines differences between meaning retention and verbatim memory, we focused on how different linguistic factors affect the retention of surface linguistic information. We examined three grammatical alternations in German that differed in involvement of changes in morpho-syntax and/or information structure, while their propositional meaning is unaffected: voice (active vs. passive), adverb positioning, different realizations of conditional clauses. Single sentences were presented and repeated, either identical or modified according to the grammatical alternation (with controlled interval between them). Results for native (N = 60) and non-native (N = 58) German participants show longer fixation durations for modified versus unmodified sentences when information structural changes are involved (voice, adverb position). In contrast, mere surface grammatical changes without a functional component (conditional clauses) did not lead to different reading behavior. Sensitivity to the manipulation was not influenced by language (L1, L2) or repetition interval. The study provides novel evidence that linguistic factors affect verbatim retention and highlights the importance of eye-tracking as a sensitive measure of implicit memory.

No evidence of fast mapping in healthy adults using an implicit memory measure: failures to replicate the lexical competition results of Coutanche and Thompson-Schill (2014)

ABSTRACT Fast mapping (FM) is a hypothetical, incidental learning process that allows rapid acquisition of new words. Using an implicit reaction time measure in a FM paradigm, Coutanche and Thompson-Schill (Coutanche, M. N., & Thompson-Schill, S. L. (2014). Fast mapping rapidly integrates information into existing memory networks. Journal of Experimental Psychology: General, 143(6), 2296–2303. https://doi.org/10.1037/xge0000020) showed evidence of lexical competition within 10 min of non-words being learned as names of unknown items, consistent with same-day lexicalisation. Here, Experiment 1 was a methodological replication (N = 28/group) that found no evidence of this RT competition effect. Instead, a post-hoc analysis suggested evidence of semantic priming. Experiment 2 (N = 60/group, online study, pre-registered on OSF) tested whether semantic priming remained when making the stimulus set fully counterbalanced. No evidence for either lexical competition nor semantic priming was detected. Experiment 3 (n = 64, online study, pre-registered on OSF) tested whether referent (a)typicality boosted lexical competition (Coutanche, M. N., & Koch, G. E. (2017). Variation across individuals and items determine learning outcomes from fast mapping. Neuropsychologia, 106, 187–193. https://doi.org/10.1016/j.neuropsychologia.2017.09.029), but again no evidence of lexical competition was observed, and Bayes Factors for the data combined across all three experiments supported the hypothesis that there is no effect of lexical competition under FM conditions. These results, together with our previous work, question whether fast mapping exists in healthy adults, at least using this specific FM paradigm.

An ERP measure of non-conscious memory reveals dissociable implicit processes in human recognition using an open-source automated analytic pipeline.

Non-conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event-related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal-dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = 54), applying new controls for construct validity, and developing an improved, open-source tool for automated analysis of the procedure used for equating levels of memory awareness. Results faithfully reproduced prior ERP findings of parietal effects that a series of systematic control analyses validated were not contributed to nor contaminated by explicit memory. Implicit memory effects extended from 600 to 1000 ms, localized to right parietal sites. These ERP effects were found to be behaviorally relevant and specific in predicting implicit memory response times, and were topographically dissociable from other traditional ERP measures of implicit memory (miss vs. correct rejections) that instead occurred in left parietal regions. Results suggest first that equating for reported awareness of memory strength is a valid, powerful new method for revealing neural correlates of non-conscious human memory, and second, behavioral correlations suggest that these implicit effects reflect a pure form of priming, whereas misses represent fluency leading to the subjective experience of familiarity.

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.

Dementia Caregiving and Cognition: An Extension of the Stress Process Model

As cases of Alzheimer’s disease and related dementias (ADRD) continue to rise, informal caregivers are critical resources in providing dementia care, yet caregiving is associated with high levels of burden, stress, anxiety and depression. Caregiving can be a prolonged and stressful experience, and impaired cognitive functioning in caregivers could impact their own health and quality of life and compromise the quality of care provided to their care-recipient. Thus, the purpose of the current study is to use the Stress Process Model as a guiding theoretical framework to identify whether primary stressors (e.g., care recipient functional status, cognitive problems) or secondary stressors (e.g., loss of self, economic conflict) predict performance across seven domains of cognition in 50 primary ADRD caregivers. Hierarchical regression analyses were used to examine which primary and secondary stressors emerge as predictors of cognitive performance. Results indicated that primary stressors (e.g., problematic dementia behaviors and relational deprivation) significantly predicted working memory performance and secondary stressors (e.g., economic strain, loss of self) significantly predicted implicit memory performance. Additionally, higher levels of caregiver burden predicted worse performance on executive functioning and implicit memory measures. Overall, the findings of this study indicate that the stress associated with caregiving may have adverse effects beyond psychosocial outcomes, and findings can be used to inform policies and practices with regard to caregiver health and well-being.

Differences in cognitive performance between informal caregivers and non-caregivers

ABSTRACT Extensive literature exists documenting the relationship between stress and cognition. Caregiving for an individual with Alzheimer’s disease can be aunique and chronic stress experience due to the increasing dependency of the care-recipient as the disease progresses. The current study examines the relationship between stress and cognitive performance in 47 dementia caregivers compared to 47 noncaregiver control participants matched on age, gender, and education. Participants completed measures assessing stress (measured via the Perceived Stress Scale) and seven domains of cognition including episodic memory, working memory, executive functioning, attention, visuospatial processing, processing speed, and implicit memory. Results showed that caregivers had poorer performance than non-caregivers on certain measures of episodic memory, working memory, and executive functioning; while no significant differences were observed on measures of attention, visuospatial processing, processing speed, or implicit memory. In addition, when controlling for general stress, caregiver performance on measures of processing speed and visuospatial processing was also poorer than non-caregivers. By controlling for levels of general stress that may not be related to caregiving, these results show that differences in cognitive performance are unlikely to be explained by general stress alone.

A Novel Test of Pure Irrelevance-Induced Blindness

Load theory claims that bottom-up attention is possible under conditions of low perceptual load but not high perceptual load. At variance with this claim, a recent one-trial study showed that under low load, with only two colors in the display – a ring and a disk –, an instruction to process only one of the two stimuli led to better memory performance for the color of the relevant than of the irrelevant stimulus. Control experiments showed that if instructed to pay attention to both objects, participants were able to memorize both colors. Thus, stimulus irrelevance diminished the likelihood of memory for a color stimulus under low perceptual-load conditions. Yet, we noted less than optimal design features in that prior study: a lack of more implicit priming measures of memory or attention and an interval between color stimulus presentation and memory test that probably exceeded 500 ms. We took care of these problems in the current one-trial study by improving the retrieval displays while leaving the encoding displays as in the original study and found that the results only partly replicated prior findings. In particular, there was no evidence of irrelevance-induced blindness under conditions in which a ring was designated as relevant, surrounding an irrelevant disk. However, a continuously cumulative meta-analysis across past and present experiments showed that our results do not refute the irrelevance-induced effects entirely. We conclude with recommendations for future tests of load theory.

Little evidence for Fast Mapping (FM) in adults: A review and discussion

ABSTRACTConventional memory theory proposes that the hippocampus is initially responsible for encoding new information, before this responsibility is gradually transferred to the neocortex. Therefore, a report in 2011 by Sharon et al. of hippocampal-independent learning in humans was notable. These authors reported normal learning of new object-name associations under a Fast Mapping (FM) procedure in adults with hippocampal damage, who were amnesic according to more conventional explicit memorisation procedures. FM is an incidental learning paradigm, inspired by vocabulary acquisition in children, which is hypothesised to allow rapid, cortical-based memory formation. In the years since the original report, there has been, understandably, a growing interest in adult FM, not only because of its theoretical importance, but also because of its potential to help rehabilitate individuals with memory problems. We review the FM literature in individuals with amnesia and in healthy adults, using both explicit and implicit memory measures. Contrary to other recent reviews, we conclude that the evidence for FM in adults is weak, and restraint is needed before assuming the phenomenon exists.

Capturing spontaneous trait inference with the modified free association paradigm

Spontaneous Trait Inference (STI) is a psychological phenomenon that allows people to infer personality traits from others' behaviors without any intention or awareness. This phenomenon helps us organize our complex social world and ultimately it shapes our interaction with others. The goal of this manuscript is 1) to conduct a systematic analysis of the different types of measures that are currently used to detect inferences, 2) to identify their main limitations and 3) to propose a new paradigm that overcomes most of these limitations. The new paradigm is based on the modified free association task that Hourihan and MacLeod (2007) proposed as a pure conceptual implicit memory measure. This new paradigm simultaneously overcomes the contamination problem of memory measures and the dependency on data-driven processing of the activation measures. In the presented experiments we use the modified free association paradigm to detect STIs and also to compare its results to the naming task and the modified Stroop task. We show that this measure is able to reliably detect STI and discuss why it is more appropriate to study inferences. Additionally, we show that it can be used to investigate the underlying processes responsible for STI and to distinguish it from similar but different phenomena like Spontaneous Trait Transference. This manuscript focuses on STIs, but the arguments presented here apply to any research field that investigates spontaneous inference making.

The Development of Implicit Memory From Infancy to Childhood: On Average Performance Levels and Interindividual Differences.

The present multimethod longitudinal study aimed at investigating development and stability of implicit memory during infancy and early childhood. A total of 134 children were followed longitudinally from 3months to 3years of life assessing different age-appropriate measures of implicit memory. Results from structural equationmodeling give further evidence that implicit memory is stable from 9months of life on, with earlier performance predicting later performance. Second, it was found that implicit memory is present from early on, and no age-related improvements are found from 3months on. Results are discussed with respect to the basic brain structures implicit memory builds on, as well as methodological issues.

Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep.

It has been debated whether different stages in the human sleep cycle preferentially mediate the consolidation of explicit and implicit memories, or whether all of the stages in succession are necessary for optimal consolidation. Here we investigated whether the selective deprivation of slow wave sleep (SWS) or rapid eye movement (REM) sleep over an entire night would have a specific effect on consolidation in explicit and implicit memory tasks. Participants completed a set of explicit and implicit memory tasks at night, prior to sleep. They had 1 control night of undisturbed sleep and 2 experimental nights, during which either SWS or REM sleep was selectively deprived across the entire night (sleep conditions counterbalanced across participants). Polysomnography recordings quantified precisely the amount of SWS and REM sleep that occurred during each of the sleep conditions, and spindle counts were recorded. In the morning, participants completed the experimental tasks in the same sequence as the night before. SWS deprivation disrupted the consolidation of explicit memories for visuospatial information (ηp2 = .23), and both SWS (ηp2 = .53) and REM sleep (ηp2 = .52) deprivation adversely affected explicit verbal recall. Neither SWS nor REM sleep deprivation affected aspects of short-term or working memory, and did not affect measures of verbal implicit memory. Spindle counts did not correlate significantly with memory performance. These findings demonstrate the importance of measuring the sleep cycles throughout the entire night, and the contribution of both SWS and REM sleep to memory consolidation. (PsycINFO Database Record

Scanning of Face-Scene or Object-Scene Pairs Reveals Implicit Relational Memory

The hippocampus is thought to play a role in the formation of memories of relations among items in a scene (Cohen and Eichenbaum, 1993). Recently, we described a change detection task in which visual scanning of objects in a scene indicated explicit memory for those objects, and is thought to require hippocampal function (Chau, Murphy, Rosenbaum, Ryan, & Hoffman, 2010). In contrast, a task pairing faces and scenes revealed that the scanning of faces can be used as a measure of implicit memory, yet it, too, is associated with hippocampal function (Hannula & Ranganath, 2009). One difference between tasks is that the latter was never tested with objectscene pairs. In this study, we replicated the face-scene task, and added an object-scene condition to determine if the difference in scanning of previously shown pairs exists for objects-scene pairs and if, as with faces, this bias exists in the absence of explicit recall. Paired items were viewed preferentially, whether the items were faces or objects, and irrespective of whether recall was implicit or explicit. The bias towards the paired image emerged within the first 500 ms of viewing for all pairs, and the protracted response was stronger for explicit than implicit pairs. These results suggest that this task is effective whether using face or object stimuli, and could be used to tease apart the role of the hippocampus in explicit and implicit memory formation. Furthermore, its use of non-verbal measurements makes it amenable for use in animal models.Authors: Branfield Day, Leora R.; Bartlett, Adrian M.; Leonard, Timothy K. and Hoffman, Kari L.

Dissociating explicit and implicit effects of cross-media advertising

Knowledge of cross-media advertising effects is mainly based on explicit psychological measures, such as self-reports. To fully understand the mechanisms responsible for the success of cross-media advertising, it is important to also use implicit measures. We used both types of measures to assess whether exposure to different media combinations affects the cognitive and evaluative impact of advertising. Results show that participants performed better on all explicit and implicit measures of memory and brand preference after exposure (versus no exposure) to target ads, which validated the use of these measures. Comparison of cross-media versus single medium exposure showed differences on the explicit level, but not on the implicit level. This suggests (1) that cross-media advantages may be driven by explicit rather than implicit memory mechanisms, and (2) that implicit advertising effects may require more drastic manipulations than context changes, such as varying the combination of media used for exposure to advertising.

A critical role of the human hippocampus in an electrophysiological measure of implicit memory

The hippocampus has traditionally been thought to be critical for conscious explicit memory but not necessary for unconscious implicit memory processing. In a recent study of a group of mild amnesia patients with evidence of MTL damage limited to the hippocampus, subjects were tested on a direct test of item recognition confidence while electroencephalogram (EEG) was acquired, and revealed intact measures of explicit memory from 400 to 600ms (mid-frontal old–new effect, FN400). The current investigation re-analyzed this data to study event-related potentials (ERPs) of implicit memory, using a recently developed procedure that eliminated declarative memory differences. Prior ERP findings from this technique were first replicated in two independent matched control groups, which exhibited reliable implicit memory effects in posterior scalp regions from 400 to 600ms, which were topographically dissociated from the explicit memory effects of familiarity. However, patients were found to be dramatically impaired in implicit memory effects relative to control subjects, as quantified by a reliable condition × group interaction. Several control analyses were conducted to consider alternative factors that could account for the results, including outliers, sample size, age, or contamination by explicit memory, and each of these factors was systematically ruled out. Results suggest that the hippocampus plays a fundamental role in aspects of memory processing that are beyond conscious awareness. The current findings therefore indicate that both memory systems of implicit and explicit memory may rely upon the same neural structures – but function in different physiological ways.

Prescription drug advertisements and older adults: a case for implicit memory

Purpose – Prescription drug advertisements are commonly seen in magazines and on television. Many drug ads are targeted toward older adults, who tend to use more medications and suffer from more chronic conditions. Nonetheless, the effectiveness of such advertising remains uncertain. The aim of this paper is to compare implicit and explicit memory for drug ads in older and younger adults. Design/methodology/approach – Older adults typically perform more poorly than young adults on explicit memory tasks, but not on implicit memory tasks. The current study measured implicit memory with an incidental ratings exercise and an indirect test of preference; explicit memory was also measured with intentional studying and a direct test of recognition. The study was a 2 x 2 mixed experimental design with one between-participants variable and one within-participants variable. The between-participants variable was age group (older vs younger adults) and the within-participants variable was implicit and explicit memory. The memory test measures were the outcome variables of the study. Findings – The results showed no age difference for implicit memory for drug ads, but an age difference was found for explicit memory for the ads. The implicit memory manipulation succeeded in demonstrating that drug ads are persuasive, suggesting that a complete assessment of advertising effectiveness should include a test of implicit memory. Research limitations/implications – The fact that age differences were not found for implicit memory, but were found for explicit memory, is not surprising. Practical implications – The study is of theoretical significance because it contributes to cognitive aging research and examines memory within an everyday context. The study is of practical significance because pharmaceutical companies spend vast amounts of money on prescription drug advertisements that may or may not be effective with older adults. The component of this study that may be most important is that the results expanded everyday memory research to another applied context using an implicit memory measure, and the indirect test of memory demonstrated that the prescription drug advertising was effective. Originality/value – Although the findings were consistent with previous research, the study focuses on the real-world context of direct-to-consumer advertising for prescription drugs. Given that older adults have poorer explicit memory than younger adults, but not poorer implicit memory, it is particularly important for advertisers to use implicit memory measures when assessing advertisements aimed at older adult consumers. Marketers of pharmaceutical drug companies must remain aware that the memory abilities of their potential customers are extremely variable, and in some cases, limited.

Online Advertisements and Conceptual Implicit Memory: Advances in Theory and Methodology

SummaryWe conducted three experiments to further our understanding, both theoretically and methodologically, of conceptual implicit memory within the advertising context. Results from the first experiment confirmed what previous research had suggested: using a brand generation task is a conceptual implicit memory measure. The first experiment also demonstrated that conceptual priming can be found using realistic‐looking advertisements embedded within a news website. Results from Experiments 2 and 3 suggest that not only is providing specific encoding instructions not necessary to induce conceptual or semantic processing but also that there were no differences based on whether the experimental procedure was conducted in a laboratory or online. Together, these results have implications for increasing the ecological validity of this type of research. By allowing participants to view realistic advertisements outside of a laboratory without specific encoding instructions, the procedure much more closely mimics how individuals actually interact with advertisements in real life. Copyright © 2013 John Wiley & Sons, Ltd.

Repetition Suppression and Multi-Voxel Pattern Similarity Differentially Track Implicit and Explicit Visual Memory

Repeated exposure to a visual stimulus is associated with corresponding reductions in neural activity, particularly within visual cortical areas. It has been argued that this phenomenon of repetition suppression is related to increases in processing fluency or implicit memory. However, repetition of a visual stimulus can also be considered in terms of the similarity of the pattern of neural activity elicited at each exposure--a measure that has recently been linked to explicit memory. Despite the popularity of each of these measures, direct comparisons between the two have been limited, and the extent to which they differentially (or similarly) relate to behavioral measures of memory has not been clearly established. In the present study, we compared repetition suppression and pattern similarity as predictors of both implicit and explicit memory. Using functional magnetic resonance imaging, we scanned 20 participants while they viewed and categorized repeated presentations of scenes. Repetition priming (facilitated categorization across repetitions) was used as a measure of implicit memory, and subsequent scene recognition was used as a measure of explicit memory. We found that repetition priming was predicted by repetition suppression in prefrontal, parietal, and occipitotemporal regions; however, repetition priming was not predicted by pattern similarity. In contrast, subsequent explicit memory was predicted by pattern similarity (across repetitions) in some of the same occipitotemporal regions that exhibited a relationship between priming and repetition suppression; however, explicit memory was not related to repetition suppression. This striking double dissociation indicates that repetition suppression and pattern similarity differentially track implicit and explicit learning.

Singlemedium- versus multimediacampagnes

Singlemedium- versus multimedia campaigns: exposure effects on implicit versus explicit memory, brand attitude and purchase intention Singlemedium- versus multimedia campaigns: exposure effects on implicit versus explicit memory, brand attitude and purchase intention The aim of this study is to introduce an alternative method to determine the potential synergy effects of multimedia campaigns. By making use of an implicit memory measure in combination with the common explicit measures, the scope and limits of the synergy effect were explored. Eighty-two participants were exposed to one of four media conditions (two multimedia conditions and two repeated medium conditions). The results showed a number of effects in favor of the multimedia campaigns. Participants seem to learn implicitly from repeated exposure to an advertisement message in multiple media, because priming only improved the memory performances of participants in the multimedia conditions. In the same way, participants in the synergistic conditions formed higher purchase intentions. These increased purchase intentions occurred without a significantly more favorable attitude compared to the repeated condition, this result may confirm that implicit memory is closer to the behavioral tendencies of consumers.

Implicit memory in Korsakoff's syndrome: a review of procedural learning and priming studies.

Korsakoff's syndrome (KS) is characterized by dense anterograde amnesia resulting from damage to the diencephalon region, typically resulting from chronic alcohol abuse and thiamine deficiency. This review assesses the integrity of the implicit memory system in KS, focusing on studies of procedural learning and priming. KS patients are impaired on several measures of procedural memory, most likely due to impairment in cognitive functions associated with alcohol-related neural damage outside of the diencephalon. The pattern of performance on tasks of implicit priming suggests reliance on a residual, non-flexible memory operating more or less in an automatic fashion. Our review concludes that whether measures of implicit memory reveal intact or impaired performance in individuals with KS depends heavily on specific task parameters and demands, including timing between stimuli, the specific nature of the stimuli used in a task, and the integrity of supportive cognitive functions necessary for performance.

The Medial Temporal Lobe Supports Conceptual Implicit Memory

The medial temporal lobe (MTL) is generally thought to be critical for explicit, but not implicit, memory. Here, we demonstrate that the perirhinal cortex (PRc), within the MTL, plays a role in conceptually-driven implicit memory. Amnesic patients with MTL lesions that converged on the left PRc exhibited deficits on two conceptual implicit tasks (i.e., exemplar generation and semantic decision). A separate functional magnetic resonance imaging (fMRI) study in healthy subjects indicated that PRc activation during encoding of words was predictive of subsequent exemplar generation. Moreover, across subjects, the magnitude of the fMRI and behavioral conceptual priming effects were directly related. Additionally, the PRc region implicated in the fMRI study was the same region of maximal lesion overlap in the patients with impaired conceptual priming. These patient and imaging results converge to suggest that the PRc plays a critical role in conceptual implicit memory, and possibly conceptual processing in general.