Source Monitoring: ERP Evidence for Greater Reactivity to Nontarget Information in Older Adults

Event-Related Potentials (ERPs) were collected concurrently with stimulus presentation during a source monitoring task. Younger adults were less likely than older adults to make source monitoring errors and their ERP records showed far greater discrimination between target stimuli and familiar but nontarget foils. Older adults not only made more source errors but produced high amplitude late positivities to the nontarget foils even when these foils were correctly rejected. Under divided attention conditions, younger adults performance was similar to that of the older adults both behaviorally and electrophysiologically. These data illustrate the role that attentional resources play in the ability to inhibit response tendencies and suggest that age differences in source monitoring may be more related to attentional control than inefficiencies in the encoding of contextual information. As well, they suggest that the ERP late positivity may represent a more general response to item salience rather than serve as an index of recollection as is the current view.     

Cognitive mechanisms of false facial recognition in older adults

Older adults show elevated false alarm rates on recognition memory tests involving faces in comparison to younger adults. It has been proposed that this age-related increase in false facial recognition reflects a deficit in recollection and a corresponding increase in the use of familiarity when making memory decisions. To test this hypothesis, we examined the performance of 40 older adults and 40 younger adults on a face recognition memory paradigm involving three different types of lures with varying levels of familiarity. A robust age effect was found, with older adults demonstrating a markedly heightened false alarm rate in comparison to younger adults for "familiarized lures" that were exact repetitions of faces encountered earlier in the experiment, but outside the study list, and therefore required accurate recollection of contextual information to reject. By contrast, there were no age differences in false alarms to "conjunction lures" that recombined parts of study list faces, or to entirely new faces. Overall, the pattern of false recognition errors observed in older adults was consistent with excessive reliance on a familiarity-based response strategy. Specifically, in the absence of recollection older adults appeared to base their memory decisions on item familiarity, as evidenced by a linear increase in false alarm rates with increasing familiarity of the lures. These findings support the notion that automatic memory processes such as familiarity remain invariant with age, while more controlled memory processes such as recollection show age-related decline.     

Encoding context and false recognition memories

False recognition of an extralist word that is thematically related to all words of a study list may reflect internal activation of the theme word during encoding followed by impaired source monitoring at retrieval, that is, difficulty in determining whether the word had actually been experienced or merely thought of. To assist source monitoring, distinctive visual or verbal contexts were added to study words at input. Both types of context produced similar effects: False alarms to theme-word (critical) lures were reduced; remember judgements of critical lures called old were lower; and if contextual information had been added to lists, subjects indicated as much for list items and associated critical foils identified as old. The visual and verbal contexts used in the present studies were held to disrupt semantic categorisation of list words at input and to facilitate source monitoring at output.     

Encoding context and false recognition memories

False recognition of an extralist word that is thematically related to all words of a study list may reflect internal activation of the theme word during encoding followed by impaired source monitoring at retrieval, that is, difficulty in determining whether the word had actually been experienced or merely thought of. To assist source monitoring, distinctive visual or verbal contexts were added to study words at input. Both types of context produced similar effects: False alarms to theme‐word (critical) lures were reduced; remember judgements of critical lures called old were lower; and if contextual information had been added to lists, subjects indicated as much for list items and associated critical foils identified as old. The visual and verbal contexts used in the present studies were held to disrupt semantic categorisation of list words at input and to facilitate source monitoring at output.     

Greater priming for previously distracting information in young than older adults when suppression is ruled out

The use of previously distracting information on memory tests with indirect instructions is usually age-equivalent, while young adults typically show greater explicit memory for such information. This could reflect qualitatively distinct initial processing (encoding) of distracting information by younger and older adults, but could also be caused by greater suppression of such information by younger adults on tasks with indirect instructions. In Experiment 1, young and older adults read stories containing distracting words, which they ignored, before studying a list of words containing previously distracting items for a free recall task. Half the participants were informed of the presence of previously distracting items in the study list prior to recall (direct instruction), and half were not (indirect instruction). Recall of previously distracting words was age-equivalent in the indirect condition, but young adults recalled more distracting words in the direct condition. In Experiment 2, participants performed the continuous identification with recognition task, which captures a measure of perceptual priming and recognition on each trial, and is immune to suppression. Priming and recognition of previously distracting words was greater in younger than older adults, suggesting that the young engage in more successful suppression of previously distracting information on tasks in which its relevance is not overtly signaled.     

Recognition of familiar and unfamiliar melodies in normal aging and Alzheimer’s disease

We tested normal young and elderly adults and elderly Alzheimer’s disease (AD) patients on recognition memory for tunes. In Experiment 1, AD patients and age-matched controls received a study list and an old/new recognition test of highly familiar, traditional tunes, followed by a study list and test of novel tunes. The controls performed better than did the AD patients. The controls showed the “mirror effect” of increased hits and reduced false alarms for traditional versus novel tunes, whereas the patients false-alarmed as often to traditional tunes as to novel tunes. Experiment 2 compared young adults and healthy elderly persons using a similar design. Performance was lower in the elderly group, but both younger and older subjects showed the mirror effect. Experiment 3 produced confusion between preexperimental familiarity and intraexperimental familiarity by mixing traditional and novel tunes in the study lists and tests. Here, the subjects in both age groups resembled the patients of Experiment 1 in failing to show the mirror effect. Older subjects again performed more poorly, and they differed qualitatively from younger subjects in setting stricter criteria for more nameable tunes. Distinguishing different sources of global familiarity is a factor in tune recognition, and the data suggest that this type of source monitoring is impaired in AD and involves different strategies in younger and older adults.     

The effect of forced recall on illusory recollection in younger and older adults

The effect of an initial forced recall test on later recall and recognition tests was examined in younger and older adults. Subjects were presented with categorized word lists and given an initial test under standard cued recall instructions (with a warning against guessing) or forced recall instructions (that required guessing); subjects were later given a cued recall test for the original list items. In 2 experiments, initial forced recall resulted in higher levels of illusory memories on subsequent tests (relative to initial cued recall), especially for older adults. Older adults were more likely to say they remembered rather than knew that forced guesses had occurred in the original study episode. The effect persisted despite a strong warning against making errors in Experiment 2. When a source monitoring test was given, older adults had more difficulty than younger adults in identifying the source of items they had originally produced as guesses. If conditions encourage subjects to guess on a first memory test, they are likely to recollect these guesses as actual memories on later tests. This effect is exaggerated in older adults, probably because of their greater source monitoring difficulties. Both dual process and source monitoring theories provide insight into these findings.     

Effects of repetition on age differences in associative recognition

The study reported here examined the effect of repetition on age differences in associative recognition using a paradigm designed to encourage recollection at test. Young and older adults studied lists of unrelated word pairs presented one, two, four, or eight times. Test lists contained old (intact) pairs, pairs consisting of old words that had been studied with other partners (rearranged lures), and pairs consisting of two unstudied words (new lures). Participants gave old/new responses and then indicated whether their responses were based on details that they could recollect or on familiarity. Older adults exhibited an ironic effect of repetition—an increase in false alarms on rearranged lures with more study opportunities—whereas young adults did not. Older adults also claimed to recall details of the study episode for rearranged lures whose constituent words were presented more frequently, but this was not true for young adults. Although both young and older adults said that they based correct rejections of rearranged lures on memory for details of the study episode, this effect was stronger for young adults. The observed age differences are consistent with older adults having reduced use of recollection in associative recognition tasks.     

Remembering words not presented in sentences: How study context changes patterns of false memories

People falsely endorse semantic associates and morpheme rearrangements of studied words at high rates in recognition testing. The coexistence of these results is paradoxical: Models of reading that presume automatic extraction of meaning cannot account for elevated false memory for foils that are related to studied stimuli only by their visual form; models without such a process cannot account for false memory for semantic foils. Here we show how sentence and list study contexts encourage different encoding modes and consequently lead to different patterns of memory errors. Participants studied compound words, such as tailspin and floodgate, as single words or embedded in sentences. We show that sentence contexts led subjects to be better able to discriminate conjunction lures (e.g., tailgate) from old words than did list contexts. Conversely, list contexts led to superior discrimination of semantic lures (e.g., nosedive) from old words than did sentence contexts.     

The effects of age and divided attention on spontaneous recognition

Studies of recognition typically involve tests in which the participant’s memory for a stimulus is directly questioned. There are occasions however, in which memory occurs more spontaneously (e.g., an acquaintance seeming familiar out of context). Spontaneous recognition was investigated in a novel paradigm involving study of pictures and words followed by recognition judgments on stimuli with an old or new word superimposed over an old or new picture. Participants were instructed to make their recognition decision on either the picture or word and to ignore the distracting stimulus. Spontaneous recognition was measured as the influence of old vs. new distracters on target recognition. Across two experiments, older adults and younger adults placed under divided-attention showed a greater tendency to spontaneously recognize old distracters as compared to full-attention younger adults. The occurrence of spontaneous recognition is discussed in relation to ability to constrain retrieval to goal-relevant information.     

Two types of recollection-based monitoring in younger and older adults: Recall-to-reject and the distinctiveness heuristic

People often use recollection to avoid false memories. At least two types of recollection-based monitoring processes can be identified in the literature. Recall-to-reject is based on the recall of logically inconsistent information (which disqualifies the false event from having occurred), whereas the distinctiveness heuristic is based on the failure to recall to-be-expected information (which is diagnostic of non-occurrence). We attempted to investigate these hypothetical monitoring processes in a single task, as a first step at delineating the functional relationship between them. By design, participants could reject familiar lures by (1) recalling them from a to-be-excluded list (recall-to-reject) or (2) realising the absence of expected picture recollections (the distinctiveness heuristic). Both manipulations reduced false recognition in young adults, suggesting that these two types of monitoring were deployed on the same test. In contrast, older adults had limited success in reducing false recognition with either manipulation, indicating deficits in recollection-based monitoring processes. Depending on how a retrieval task is structured, attempts to use one monitoring process might interfere with another, especially in older adults.     

Negativity bias in false memory: moderation by neuroticism after a delay

The negativity bias is the tendency for individuals to give greater weight, and often exhibit more rapid and extreme responses, to negative than positive information. Using the Deese-Roediger-McDermott illusory memory paradigm, the current study sought to examine how the negativity bias might affect both correct recognition for negative and positive words and false recognition for associated critical lures, as well as how trait neuroticism might moderate these effects. In two experiments, participants studied lists of words composed of semantic associates of an unpresented word (the critical lure). Half of the lists were comprised of positive words and half were comprised of negative words. As expected, individuals remembered negative list words better than positive list words, consistent with a negativity bias in correct recognition. When tested immediately (Experiment 1), individuals also exhibited greater false memory for negative versus positive critical lures. When tested after a 24-hr delay (Experiment 2), individuals higher in neuroticism maintained greater false memory for negative versus positive critical lures, but those lower in neuroticism showed no difference in false memory between negative and positive critical lures. Possible mechanisms and implications for mental health disorders are discussed.     

Aging and recognition memory for emotional words: A bias account

The present study investigated age-related differences in the locus of the emotional enhancement effect in recognition memory. Younger and older adults studied an emotion-heterogeneous list followed by a forced choice recognition memory test. Luce’s (1963) similarity choice model was used to assess whether emotional valence impacts memory sensitivity or response bias. Results revealed that the emotional enhancement effect in both age groups was due to a more liberal response bias for emotional words. However, the pattern of bias differed, with younger adults more willing to classify negative words as old and older adults more willing to classify positive words as old. The results challenge the conclusion that emotional words are more memorable than neutral words.     

Remembering Words Never Presented: False Memory Effects in Dementia of the Alzheimer Type

Thirty-five young adults, 35 older adults and 29 individuals with dementia of the Alzheimer’s type studied lists of semantically related words (e.g., thread, pin, sewing) that converged on a non-presented lure (needle). Compared to the young adults, older adults remembered (recall and recognition tests) fewer studied items but falsely remembered more non-presented lures. Memory for studied items was lower in the DAT group compared to normal elders. The DAT group did recall some non-presented lures, although unlike the older adults, recall of non-presented lures was not elevated compared to veridical memory. Similar to the normal elders, the DAT group showed increased susceptibility to false recognition of non-presented lures. Susceptibility to false recognition did not vary as a function of disease severity.     

The effects of emotional content and aging on false memories

After studying a list of words related to a nonpresented lure word, people often falsely recall or recognize the nonpresented lure. Older adults are particularly susceptible to these forms of false memories. The age-related false memory enhancement likely occurs because older adults do not encode, or later retrieve, items in enough detail to allow them to discriminate between presented words and other associated but nonpresented items. Pesta, Murphy, and Sanders (2001) suggested that the emotional salience of the lures may provide distinctiveness, so that individuals would be less likely to endorse an emotional lure as a studied item than to endorse a neutral lure. In the present investigation, young and older adults were less likely to falsely recall or recognize emotional, as compared with neutral, lures. Both age groups appeared capable of using the distinctiveness of the emotional lures to reduce, although not to eliminate, false recall and recognition.     

Cognitive monitoring and strategy choice in younger and older adults

Younger (24- to 39-year-old) and older (60- to 88-year-old) adults learned a list of vocabulary words; one half of the words were studied using a generally more powerful strategy (mnemonic keyword method), and one half mediated with a less powerful approach (generating semantic contexts). Before using these strategies as part of the experiment, neither younger nor older adults judged that the keyword method was more effective and neither group preferred one strategy over the other. After using the strategies and taking a test of strategically studied unfamiliar vocabulary words, the younger subjects reported accurately the relative effectiveness of the two strategies and selected the one that had worked better for them to apply to a subsequent list of vocabulary items. The older participants were not as aware of the differential potency of the strategies and did not rely as much as did the younger subjects on knowledge of strategy utility in making strategy choices. In short, metacognitive awareness of strategy effects produced by monitoring and use of metacognitive awareness in regulating strategy choice were more pronounced in the younger compared with the older sample in this study.     

Word-List-Learning Performance in Younger and Older Adults: Intra-Individual Performance Variability and False Memory

ABSTRACT

We investigated the word-list-learning performance of younger and older adults over 4 consecutive days at different times of day to study age-related differences in consistency of performance over time and the influence of circadian variation on performance. Eighteen younger (M age, 23.4 years) and 18 older (M age, 73.3 years) men and women participated. The start time of testing alternated between morning and early evening across the 4 days of testing. On each test day, participants learned a different list of 15 unrelated words over four learning trials. As expected, younger adults performed better than older adults on immediate recall, delayed recall, and recognition. Contrary to our expectations, time of day did not significantly influence recall or recognition performance in either the older or younger adults. Older adults did show a greater incidence of false memory (i.e., previously learned list intrusions in free recall and false alarms in recognition) than younger adults. Older adults also exhibited greater intra-individual performance variability on the measures of false memory across test days. This variability was not related to circadian variation. False memory and variability of performance have both been linked to frontal systems dysfunction. The findings presented here are consistent with the notion that changes in cognition with aging in part reflect age-related decline in frontal lobe function.     

Older adults encode--but do not always use--perceptual details: intentional versus unintentional effects of detail on memory judgments

Investigations of memory deficits in older individuals have concentrated on their increased likelihood of forgetting events or details of events that were actually encountered (errors of omission). However, mounting evidence demonstrates that normal cognitive aging also is associated with an increased propensity for errors of commission-shown in false alarms or false recognition. The present study examined the origins of this age difference. Older and younger adults each performed three types of memory tasks in which details of encountered items might influence performance. Although older adults showed greater false recognition of related lures on a standard (identical) old/new episodic recognition task, older and younger adults showed parallel effects of detail on repetition priming and meaning-based episodic recognition (decreased priming and decreased meaning-based recognition for different relative to same exemplars). The results suggest that the older adults encoded details but used them less effectively than the younger adults in the recognition context requiring their deliberate, controlled use.     

False memory in aging: effects of emotional valence on word recognition accuracy

Memory is susceptible to distortions. Valence and increasing age are variables known to affect memory accuracy and may increase false alarm production. Interaction between these variables and their impact on false memory was investigated in 36 young (18-28 years) and 36 older (61-83 years) healthy adults. At study, participants viewed lists of neutral words orthographically related to negative, neutral, or positive critical lures (not presented). Memory for these words was subsequently tested with a remember-know procedure. At test, items included the words seen at study and their associated critical lures, as well as sets of orthographically related neutral words not seen at study and their associated unstudied lures. Positive valence was shown to have two opposite effects on older adults' discrimination of the lures: It improved correct rejection of unstudied lures but increased false memory for critical lures (i.e., lures associated with words studied previously). Thus, increased salience triggered by positive valence may disrupt memory accuracy in older adults when discriminating among similar events. These findings likely reflect a source memory deficit due to decreased efficiency in cognitive control processes with aging.     

Word-list-learning performance in younger and older adults: intra-individual performance variability and false memory

We investigated the word-list-learning performance of younger and older adults over 4 consecutive days at different times of day to study age-related differences in consistency of performance over time and the influence of circadian variation on performance. Eighteen younger (M age, 23.4 years) and 18 older (M age, 73.3 years) men and women participated. The start time of testing alternated between morning and early evening across the 4 days of testing. On each test day, participants learned a different list of 15 unrelated words over four learning trials. As expected, younger adults performed better than older adults on immediate recall, delayed recall, and recognition. Contrary to our expectations, time of day did not significantly influence recall or recognition performance in either the older or younger adults. Older adults did show a greater incidence of false memory (i.e., previously learned list intrusions in free recall and false alarms in recognition) than younger adults. Older adults also exhibited greater intra-individual performance variability on the measures of false memory across test days. This variability was not related to circadian variation. False memory and variability of performance have both been linked to frontal systems dysfunction. The findings presented here are consistent with the notion that changes in cognition with aging in part reflect age-related decline in frontal lobe function.