Data-driven recognition memory: a new technique and some data on age differences

Perceptual fluency affects recognition memory under deep encoding conditions promoting recollection: Evidence from an ERP study using letter-segregated method

Perceptual fluency can increase familiarity of some of the items in recognition tests and enhance attributions of these items to the past. It is not clear, however, whether perceptual fluency can influence recognition under conditions promoting recollection-based memory. To this end, we performed a systematic replication of a study by Lucas and Paller (2013) using a letter-segregated method. We recorded ERPs while participants performed recognition task in letter segregated (LS) blocks, in which new words were always composed of different letters than old words, and in letter non-segregated (LNS) blocks, in which half of the new words came from the same letter pool as the studied words (new related words), and the other half came from the other pool (new unrelated words). Unlike the Lucas and Paller study, deep encoding promoted more recollection-based memory. In the LNS blocks, the comparison between old and new unrelated words revealed early (180-260 ms) P200 old/new effect, showing that recognition can be supported by an early discrimination of perceptual differences between studied and unstudied test probes. The relatively large hit rates and relatively high sensitivity measures, as well as the late (500-700 ms) LPC old/new effects in both blocks, indicated high levels of recollection for old words. Still, recognition memory was more accurate in the LS blocks, whereas in the LNS blocks there were more false alarms for new related than for new unrelated words. This suggests that perceptual fluency derived from low-level information may influence not only familiarity, but also recollection-based memory judgments.

Impaired recollection and initially preserved familiarity in a patient with bilateral fornix transection following third ventricle colloid cyst removal: A two-year follow-up study

OBJECTIVE

Recognition memory is widely accepted as a dual process-based model, namely familiarity and recollection. However, the location of their specific neurobiological substrates remains unclear. Similar to hippocampal damage, fornix damage has been associated with recollection memory but not familiarity memory deficits. To understand the neural basis of recognition memory, determining the importance of the fornix and its hippocampal connections is essential.

METHODS

Recognition memory was examined in a 45-year-old male who underwent a complete bilateral fornix section following the removal of a third ventricle colloid cyst. The application of familiarity and recollection for recognition memory decisions was investigated via an immediate and delayed associative recognition test and an immediate and delayed forced-choice task in the patient and a control group (N = 15) over a two-year follow-up period. Complete demographic, neuropsychological, neuropsychiatric, and neuroradiological characterizations of this patient were performed.

RESULTS

Persistent immediate and delayed verbal recollection memory deficits were observed in the patient. Moreover, delayed familiarity-based recognition memory declined gradually over the follow-up period, immediate familiarity-based recognition memory was unaffected, and reduced non-verbal memory improved.

CONCLUSION

The present findings support models that the extended hippocampal system, including the fornices, does not appear to play a role in familiarity memory but is particularly important for recollection memory. Moreover, our study suggests that bilateral fornix transection may be associated with relatively functional recovery of non-verbal memory.

Effectiveness of tDCS at Improving Recognition and Reducing False Memories in Older Adults

BACKGROUND

False memories tend to increase in healthy and pathological aging, and their reduction could be useful in improving cognitive functioning. The objective of this study was to use an active-placebo method to verify whether the application of transcranial direct current stimulation (tDCS) improved true recognition and reduced false memories in healthy older people.

METHOD

Participants were 29 healthy older adults (65-78 years old) that were assigned to either an active or a placebo group; the active group received anodal stimulation at 2 mA for 20 min over F7. An experimental task was used to estimate true and false recognition. The procedure took place in two sessions on two consecutive days.

RESULTS

True recognition showed a significant main effect of sessions (p < 0.01), indicating an increase from before treatment to after it. False recognition showed a significant main effect of sessions (p < 0.01), indicating a decrease from before treatment to after it and a significant session × group interaction (p < 0.0001).

CONCLUSIONS

Overall, our results show that tDCS was an effective tool for increasing true recognition and reducing false recognition in healthy older people, and suggest that stimulation improved recall by increasing the number of items a participant could recall and reducing the number of memory errors.

Phonological false recognition produced by bottom-up automatic activation in young and older people

Two experiments explored a new procedure to implicitly induce phonological false memories in young and older people. On the study tasks, half of the words were formed from half of the letters in the alphabet, whereas the remaining words were formed from all the letters in the alphabet. On the recognition tests, there were three types of non-studied new words: critical lures formed from the same half of the letters as the studied words; distractors formed from the other half of the letters not used, and distractors formed from all the letters in the alphabet. In both experiments, the results showed that, in both young and older people, critical lures produced more false recognitions than distractors composed of all the letters in the alphabet, which, in turn, produced more false alarms than distractors composed of the letters not used during the study. These results support the predictions of the activation/monitoring models, which assume that false memories are partly due to activation spreading from items (semantically or phonologically) related to the critical words.

Targeting Adult Neurogenesis to Optimize Hippocampal Circuits in Aging

Millions of individuals suffer from age-related cognitive decline, defined by impaired memory precision. Increased understanding of hippocampal circuit mechanisms underlying memory formation suggests a role for computational processes such as pattern separation and pattern completion in memory precision. We describe evidence implicating the dentate gyrus-CA3 circuit in pattern separation and completion, and examine alterations in dentate gyrus-CA3 circuit structure and function with aging. We discuss the role of adult hippocampal neurogenesis in memory precision in adulthood and aging, as well as the circuit mechanisms underlying the integration and encoding functions of adult-born dentate granule cells. We posit that understanding these circuit mechanisms will permit generation of circuit-based endophenotypes that will edify new therapeutic strategies to optimize hippocampal encoding during aging.

Increasing the salience of fluency cues does not reduce the recognition memory impairment in Alzheimer's disease!

In Alzheimer's disease (AD), it is now well established that recollection is impaired from the beginning of the disease, whereas findings are less clear concerning familiarity. One of the most important mechanisms underlying familiarity is the sense of familiarity driven by processing fluency. In this study, we attempted to attenuate recognition memory deficits in AD by maximizing the salience of fluency cues in two conditions of a recognition memory task. In one condition, targets and foils have been created from the same pool of letters (Overlap condition). In a second condition, targets and foils have been derived from two separate pools of letters (No-Overlap condition), promoting the use of letter-driven visual and phonetic fluency. Targets and foils were low-frequency words. The memory tasks were performed by 15 patients with AD and 16 healthy controls. Both groups improved their memory performance in the No-Overlap condition compared to the Overlap condition. Patients with AD were able to use fluency cues during recognition memory as older adults did, but this did not allow to compensate for dysfunction of recognition memory processes.

Exploring recollection and familiarity impairments in Parkinson's disease

There is conflicting evidence on whether patients diagnosed with Parkinson's disease (PD) have cognitive deficits associated with episodic memory and particularly with recognition memory. The aim of the present study was to explore whether PD patients exhibit deficits in recollection and familiarity, the two processes involved in recognition. A sample of young healthy participants (22) was tested to verify that the experimental tasks were useful estimators of recognition processes. Two further samples--one of elderly controls (16) and one of PD patients (20)--were the main focus of this research. All participants were exposed to an associative recognition test aimed at estimating recollection followed by a two-alternative forced-choice (2AFC) test designed to estimate familiarity. The analyses showed a deficit in associative recognition in PD patients and no difference between elderly controls and PD patients in the 2AFC test. By contrast, young healthy participants were better than elderly controls and PD patients in both components of recognition. Further analyses of results of the 2AFC test indicated that the measure chosen to estimate conceptual familiarity was adequate.

On familiarity deficits in mild cognitive impairment: a reply to Migo and Westerberg

In this brief response to Migo and Westerberg we explain why we think that their criticism of our previous research showing familiarity deficits in mild cognitive impairment patients (MCI) is not sound. More concretely, we have replicated the effect several times previously, and we justify statistically the fact that in the previous paper we had to combine two MCI samples to demonstrate a reliable familiarity deficit. We note that there are several studies showing conflicting results. However, although the basis for these discrepancies remains uncertain, a new report has replicated the presence of deficits in familiarity, and more importantly, demonstrated its correlation with structural imaging biomarkers of Alzheimer's disease.

Manipulating letter fluency for words alters electrophysiological correlates of recognition memory

The mechanisms that give rise to familiarity memory have received intense research interest. One current topic of debate concerns the extent to which familiarity is driven by the same fluency sources that give rise to certain implicit memory phenomena. Familiarity may be tied to conceptual fluency, given that familiarity and conceptual implicit memory can exhibit similar neurocognitive properties. However, familiarity can also be driven by perceptual factors, and its neural basis under these circumstances has received less attention. Here we recorded brain potentials during recognition testing using a procedure that has previously been shown to encourage a reliance on letter information when assessing familiarity for words. Studied and unstudied words were derived either from two separate letter pools or a single letter pool ("letter-segregated" and "normal" conditions, respectively) in a within-subjects contrast. As predicted, recognition accuracy was higher in the letter-segregated relative to the normal condition. Electrophysiological analyses revealed parietal old-new effects from 500-700 ms in both conditions. In addition, a topographically dissociable occipital old-new effect from 300-700 ms was present in the letter-segregated condition only. In a second experiment, we found that similar occipital brain potentials were associated with confident false recognition of words that shared letters with studied words but were not themselves studied. These findings indicate that familiarity is a multiply determined phenomenon, and that the stimulus dimensions on which familiarity is based can moderate its neural correlates. Conceptual and perceptual contributions to familiarity vary across testing circumstances, and both must be accounted for in theories of recognition memory and its neural basis.

The role of perceptual information in familiarity-based scene recognition

A method to analyze the role of familiarity in recognizing pictures of everyday scenes is introduced. The idea is to manipulate two within-subjects conditions: an experimental condition where the scenes repeat perceptual information (e.g. buildings and/or vehicles) and a control condition. The results show the two conditions did not differ in terms of hit rates, but in the experimental condition there were significantly fewer false alarms, yielding better results, which supports the findings of past research studies that have used verbal materials. This perceptual facilitation was maintained throughout a week-long retention interval. Finally, a detailed analysis of this facilitation shows it was due to a significant reduction in false alarms on know judgments, emphasizing familiarity's role in explaining this effect.

Many roads lead to recognition: electrophysiological correlates of familiarity derived from short-term masked repetition priming

The neural mechanisms that underlie familiarity memory have been extensively investigated, but a consensus understanding remains elusive. Behavioral evidence suggests that familiarity sometimes shares sources with instances of implicit memory known as priming, in that the same increases in processing fluency that give rise to priming can engender familiarity. One underappreciated implication of this account is that patterns of neural activity that appear to index familiarity in a generic sense may instead reflect fluency-related precursors of recognition. In a novel illustration of this principle, we examined brain potentials during recognition tests for visual words. In two experiments, fluency was selectively enhanced for half of the test cues via masked repetition priming. Replicating previous findings, the proportion of words endorsed as "old" was greater for words immediately preceded by a matching masked word versus an unrelated one. In addition, N400 potentials were more positive for test cues preceded by matching versus unrelated masked words. Similar N400 differences were observed when false alarms were compared to correct rejections for the subset of unstudied words that were preceded by matching masked words. These N400 effects were topographically dissociable from other potentials that correlated with familiarity for studied words. We conclude that experiences of familiarity can have different neural correlates that signal the operation of distinct neurocognitive precursors of recognition judgments. Conceptualizations of the neural basis of recognition memory must account for a plurality of mechanisms that produce familiarity memory.

Measuring recollection and familiarity: Improving the remember/know procedure

The remember/know (RK) procedure is the most widely used method to investigate recollection and familiarity. It uses trial-by-trial reports to determine how much recollection and familiarity contribute to different kinds of recognition. Few other methods provide information about individual memory judgements and no alternative allows such direct indications of recollection and familiarity influences. Here we review how the RK procedure has been and should be used to help resolve theoretical disagreements about the processing and neural bases of components of recognition memory. Emphasis is placed on procedural weaknesses and a possible confound of recollection and familiarity with recognition memory strength. Recommendations are made about how to minimise these problems including using modified versions of the procedure. The proposals here are important for improving behavioural and lesion research, and vital for brain imaging work.

The effect of navigational expertise on wayfinding in new environments

Becoming proficient at navigation in urban environments is something that we all aspire to. Here we asked whether being an expert at wayfinding in one environment has any effect on learning new spatial layouts. Licensed London taxi drivers are among the most proficient urban navigators, training for many years to find their way around a complex and irregularly-laid out city. We first tested how well they could learn the layout of an unfamiliar town compared with a group of non-taxi drivers. Second, we investigated how effectively taxi drivers could integrate a new district into their existing spatial representation of London. We found that taxi drivers were significantly better than control participants at executing routes through the new town, and representing it at a map-like survey level. However, the benefits of navigational expertise were not universal. Compared with their performance in the new town, taxi drivers were significantly poorer at learning the layout of a new area that had to be integrated with their existing knowledge of London. We consider reasons for this picture of facilitation and limitation, in particular drawing parallels with how knowledge acquisition occurs in the context of expertise in general.

Familiarity changes as a function of perceptual shifts

This experiment compares the yes-no and forced recognition tests as methods of measuring familiarity. Participants faced a phase of 3 study-test recognition trials in which they studied words using all the letters of the alphabet (overlapping condition, O), and an additional phase in which targets and lures did not share any letters (non-overlapping condition, NO). Finally, subjects performed a forced-choice task in which they had to choose one of two new words, each from one of the subsets (Parkin et al., 2001). Results in the NO condition were better than in the O condition in the yes-no recognition test, while the forced-choice rate was significantly higher than .50, showing their sensitivity to familiarity. When the letter set of the words for study in the third list of the NO condition was switched, the difference between NO and O conditions disappeared in yes-no test, while the force-choice rate was not higher than .50. We conclude that both the yes-no test and the forced-choice test are valid and equivalent measures of familiarity under the right conditions.

Using stimulus form change to understand memorial familiarity for pictures and words in patients with mild cognitive impairment and Alzheimer's disease

Although it is generally accepted that patients with amnestic mild cognitive impairment (aMCI) and patients with Alzheimer's disease (AD) have significantly impaired recollection, recent evidence has been mixed as to whether these patients demonstrate impaired memorial familiarity. Recent work suggests that familiarity may remain intact for pictures, but not for words. Further, a recent event-related potential (ERP) study suggests that enhanced conceptual processing of pictures may underlie this intact familiarity. However, to date there has been no direct comparison of perceptual and conceptual-based familiarity for pictures and words in patients with aMCI and AD. To investigate this issue, patients with aMCI, patients with AD, and healthy older adults underwent four study-test conditions of word-word, picture-picture, word-picture, and picture-word. When stimuli undergo form change, it has been suggested that only conceptual processing can help support recognition in the absence of recollection. Our results showed that patients successfully relied on perceptual and conceptual-based familiarity to improve recognition for the within format conditions over the across format conditions. Further, results suggested that patients with aMCI and AD are able to use enhanced conceptual processing of pictures compared to words to allow them to overcome the deleterious effects of form change in a similar manner as controls. These results help us begin to understand which aspects of memory are impaired and which remain relatively intact in patients with aMCI and AD. This understanding can then in turn help us to assess, conceptualize, and build behavioral interventions to help treat these patients.

A meta-analytic review of emotion recognition and aging: implications for neuropsychological models of aging

This meta-analysis of 28 data sets (N=705 older adults, N=962 younger adults) examined age differences in emotion recognition across four modalities: faces, voices, bodies/contexts, and matching of faces to voices. The results indicate that older adults have increased difficulty recognising at least some of the basic emotions (anger, sadness, fear, disgust, surprise, happiness) in each modality, with some emotions (anger and sadness) and some modalities (face-voice matching) creating particular difficulties. The predominant pattern across all emotions and modalities was of age-related decline with the exception that there was a trend for older adults to be better than young adults at recognising disgusted facial expressions. These age-related changes are examined in the context of three theoretical perspectives-positivity effects, general cognitive decline, and more specific neuropsychological change in the social brain. We argue that the pattern of age-related change observed is most consistent with a neuropsychological model of adult aging stemming from changes in frontal and temporal volume, and/or changes in neurotransmitters.

Neurocognitive aging: prior memories hinder new hippocampal encoding

Normal aging is often accompanied by impairments in forming new memories, and studies of aging rodents have revealed structural and functional changes to the hippocampus that might point to the mechanisms behind such memory loss. In this article, we synthesize recent neurobiological and neurophysiological findings into a model of the information-processing circuit of the aging hippocampus. The key point of the model is that small concurrent changes during aging strengthen the auto-associative network of the CA3 subregion at the cost of processing new information coming in from the entorhinal cortex. As a result of such reorganization in aged memory-impaired individuals, information that is already stored would become the dominant pattern of the hippocampus to the detriment of the ability to encode new information.

Increasing the salience of fluency cues reduces the recognition memory impairment in amnesia

The present study examined whether the recognition memory deficit in amnesia would be attenuated under conditions that increased the salience of study-induced fluency. Studied and unstudied items were drawn either from separate pools of letters (no-overlap condition) or from the same pool of letters (overlap condition). Study-induced fluency was more salient in the no-overlap than in the overlap condition, because in the no-overlap condition, such fluency occurred at the letter level as well as at the word level. The recognition memory impairment in amnesia was smaller in the no-overlap than in the overlap condition. These findings are consistent with the idea that enhancing the salience of fluency cues promotes reliance on a fluency heuristic that ordinarily is not fully engaged in amnesia, and reduces the recognition memory impairment in amnesia.

False recognition and word length: A reanalysis of Roediger, Watson, McDermott, and Gallo (2001) and some new data

Roediger, Watson, McDermott, and Gallo (2001) reported a multiple regression analysis of the variables that predicted rates of false recall and recognition across lists in the Deese/Roediger-McDermott paradigm. They concluded that false recollection was predictable from the backward associative strength of critical words and list words and the veridical recall level of list words, with no independent contribution of frequency, concreteness, or length of critical words. A reanalysis of their data shows that critical word length does contribute to false recognition when it is measured relative to the length of other words in the list. Relative word length in the form of an unsigned z-score has a larger correlation with false recognition than any of the variables used by Roediger et al. and is also independently predictive of false recognition. This relationship was confirmed by the results of two recognition experiments in which false positives were significantly less frequent for words of lengths that never occurred in a studied list than for words of lengths that did occur in the study list.