Aging, imagery, and the bizarreness effect

ABSTRACT This study examined the bizarre imagery effect in young and older adults, under incidental and intentional conditions. Intentionality was manipulated across experiments, with participants receiving an incidental free recall test in Experiment 1 and an intentional test in Experiment 2. This study also examined the relation between working memory resources and the bizarreness effect. In Experiment 1 young and older adults were presented with common and bizarre sentences; they later received an incidental recall test. There were no age differences in sensitivity to the bizarreness effect in Experiment 1 when ANOVAs were used to analyze the data. However, when the bizarreness effect was examined in terms of effect size, there was evidence that younger adults produced larger bizarreness effect sizes than younger adults. Experiment 2 further explored age differences in sensitivity to the bizarreness effect by presenting young and older adults with bizarre and common sentences under intentional learning conditions. Experiment 2 failed to yield age differences as a function of item type (bizarre vs. common). In addition, Experiment 2 failed to yield significant evidence that the bizarreness effect is modulated by working memory resources. The results of this study are most consistent with the distinctiveness account of the bizarreness effect.     

Adult age differences in memory for distinctive information: Evidence from the bizarreness effect

Two experiments examined age-related differences in memory for bizarre and common pictures. In Experiment 1, a facilitative effect of bizarreness was obtained for young adults and one of the older groups, but not for the oldest group (over age 70). However, the bizarreness effect was found for even the oldest group when predominantly common lists were used in Experiment 2. It is concluded that older adults suffer from deficits in distinctive processing, but those deficits can be reduced by providing a more uniformly common context in which differences can be processed.     

The bizarre imagery effect and intention to learn

The bizarre imagery effect, better memory for bizarre stimuli than for common stimuli, is now an established finding. However, the mnemonic benefits of bizarre imagery are subject to several constraints (e.g., the use of mixed lists and free-recall tests). A further constraint on the bizarreness effect is demonstrated here. In each of two experiments, subjects were given either incidental or intentional study instructions and were asked to rate the vividness of the images they formed from the bizarre and common sentences. Contrary to conclusions based on available evidence, the bizarreness effect in free recall was manifested only with the incidental learning instructions. This additional constraint on the effect is consistent with the item-order account of bizarreness.     

Free recall accuracy for common and bizarre verbal information

A large body of empirical research suggests better free recall for bizarre than common verbal information; however, the bulk of those studies used a method that does not consider the contextual and relational accuracy of recovered memories. The conclusions drawn from that research therefore are based on tests of memory not for holistic stimuli but for decontextualized memory fragments. In response to this anomaly and recent findings suggesting that bizarre memories are more likely to be distorted than common memories, a holistic analysis of free recall for common and bizarre verbal material was conducted. Two experiments indicated that bizarreness both facilitates and disrupts recall. Specifically, better recall (both in part and in full) was found for bizarre information, but a greater tendency to merge bizarre memory fragments into other partially recovered memories was also found. This pattern of results was demonstrated under immediate and delayed testing conditions (Experiment 1) and using both incidental and intentional learning procedures (Experiment 2). Overall, the results are consistent with a weak account of disruption caused by bizarreness.     

The effect of verbal elaborations on memory in young and older adults

The Stein paradigm was used to examine the circumstances under which verbal elaborations enhance memory in young and older adults. Subjects studied target adjectives that were embedded in one of three sentence contexts that varied in elaboration of the subject-adjective relationship: (1) nonelaborated base sentences; (2) base sentences with semantically consistent, but arbitrary verbal, elaborations; and (3) base sentences with explanatory verbal elaborations that clarified the significance of the subject-adjective relationship. The presence of the elaborations was varied at encoding and retrieval, and cued recall of the target adjectives was tested with incidental and intentional learning procedures. In Experiments 1A and 1B, explanatory elaborations at encoding and retrieval yielded the largest memorial facilitation for both young and older adults, and the benefit was comparable for the incidental and intentional learning measures. In Experiment 2, age-related differences in recall were minimal with explanatory elaborations at encoding and retrieval, but larger age differences occurred in the nonelaborated comparison conditions. In Experiment 3, explanatory elaborations present at encoding but not at retrieval enhanced recall when the original Stein stimuli were used, but not with the present stimuli. The implications of these results with regard to the mnemonic efficacy of verbal elaborations for young and older adults are discussed.     

Ageing and secondary-distinctiveness-based effects: The orthographic distinctiveness effect is more robust than the bizarreness effect

Differences related to ageing were investigated in two cases of secondary-distinctiveness-based effects: the bizarreness effect and the orthographic distinctiveness effect. A secondary distinctiveness effect means that items that are unusual compared to one's general knowledge stored in permanent memory are better remembered than common items. Experiment 1 confirmed that ageing diminishes the facilitative effects of bizarreness in a mixed list design with equal numbers of bizarre and common images. We suggest that the impaired bizarreness effect in older adults (above age 70) may be due to reduced attentional resources, since no bizarreness effect was observed for younger adults in the divided attention condition. Experiment 2 studied the orthographic distinctiveness effect in ageing for the first time. Contrary to our expectations, an orthographic distinctiveness effect was observed for all participants including older adults and younger adults in a divided attention condition. Because reduced attentional resources due to normal ageing or to experimental manipulation did not impact the facilitative effects of orthographic distinctiveness, our findings suggest that the orthographic distinctiveness effect may be mediated by more automatic processing.     

Ageing and secondary-distinctiveness-based effects: The orthographic distinctiveness effect is more robust than the bizarreness effect

Differences related to ageing were investigated in two cases of secondary-distinctiveness-based effects: the bizarreness effect and the orthographic distinctiveness effect. A secondary distinctiveness effect means that items that are unusual compared to one's general knowledge stored in permanent memory are better remembered than common items. Experiment 1 confirmed that ageing diminishes the facilitative effects of bizarreness in a mixed list design with equal numbers of bizarre and common images. We suggest that the impaired bizarreness effect in older adults (above age 70) may be due to reduced attentional resources, since no bizarreness effect was observed for younger adults in the divided attention condition. Experiment 2 studied the orthographic distinctiveness effect in ageing for the first time. Contrary to our expectations, an orthographic distinctiveness effect was observed for all participants including older adults and younger adults in a divided attention condition. Because reduced attentional resources due to normal ageing or to experimental manipulation did not impact the facilitative effects of orthographic distinctiveness, our findings suggest that the orthographic distinctiveness effect may be mediated by more automatic processing.     

The bizarreness effect: evidence for the critical influence of retrieval processes

People show better memory for bizarre sentences relative to common sentences, a finding referred to as the bizarrness effect. Interestingly, this effect is typically only obtained using a mixed-list design, in which participants study common and bizarre sentences in the same list. This bizarreness effect in mixed-list designs has been explained as the result of both enhanced encoding processes and efficient retrieval processes. The present experiment was designed to isolate the unique contributions of the retrieval context to the bizarreness effect. Participants studied common sentences in one room under one set of instructions, and bizarre sentences in another room under another set of instructions. At test, participants recalled the common and bizarre sentences either together or separately. The results showed that the bizarreness effect was only obtained when participants recalled the common and bizarre items together; no bizarreness advantage emerged when participants were required to recall the common and bizarre items separately. These results suggest that differential encoding processes are not necessary for explaining the bizarreness effect in memory. Rather, retrieval of the mixed-list context appears to be critical for obtaining the effect.     

The bizarre mnemonic

Summary Five experiments measured effects of bizarre contexts on the free recall of noun triplets after brief retention intervals. More triplets were remembered from bizarre than from common contexts in short mixed lists (12 sentences) when the sentences were presented at a controlled (10 seconds/sentence) rate, regardless of incidental task (rating images for bizarreness, vividness, or memorability). The average number of words/sentence recalled, however, tended to be higher for common than for bizarre contexts. No memory benefit from bizarreness was found for pure lists nor for lists containing more than six triplets in bizarre contexts. The bizarreness effect was less when the subject controlled the rate of presentation. A sixth experiment, which tested recall after immediate and two-day retention intervals, found that the Bizarre/Common Context by Pure/Mixed List interaction increased over longer retention intervals.     

Memory for internally generated words in Alzheimer-type dementia: breakdown in encoding and semantic memory

The "generation effect" is a phenomenon in which words that are generated by the subject are remembered better than words which are read. The present experiments examined this effect in patients with mild-to-moderate dementia of the Alzheimer type (DAT), healthy elderly adults, and young adults under a variety of different encoding and retrieval conditions. Experiment 1 employed an intentional learning task with multiple study/test trials using the same list of words. While both the young and elderly adults exhibited higher recall for internally generated words than read words, the DAT patients failed to demonstrate the effect even after repeated exposures to the same stimulus list. Experiment 2 replicated this same pattern of results using an incidental learning paradigm with both recall and recognition tests. Various explanations as to why the DAT patients failed to show the generation effect were discussed with particular emphasis placed on the role of semantic memory and encoding failure.     

Investigating secondary‐distinctiveness‐based effects in aging and Alzheimer's disease patients

The aim of the present study was 2‐fold. First, two experiments were devised to further investigate secondary distinctiveness‐based effects in relation to aging. By using a repeated study‐test procedure, it aimed at restoring the bizarreness effect (Experiment 1) or at amplifying the orthographic distinctiveness (OD) effect in older adults (Experiment 2). Second, by including Alzheimer's disease patients (AD patients) in both experiments, it also aimed at instigating research on secondary distinctiveness‐based effects in relation to Alzheimer disease. The results of Experiment 1 revealed that a repeated study‐test procedure may to some extent facilitate the free recalling of bizarre images in older adults. However, the benefit of such procedure does not seem to be durable in older adults (no bizarreness effect for the last study‐test cycle) and is inefficient in AD patients. Surprisingly, for both older adults and AD patients, results of Experiment 2 revealed a similar OD effect across all study‐test cycles. The findings of both experiments were related to previous work suggesting that the bizarreness effect and the OD effect are mediated by different processing.     

Source and destination memory: Two sides of the same coin?

Whereas source memory involves remembering from whom you have heard something, destination memory involves remembering to whom you have told something. Despite its practical relevance, destination memory has been studied little. Recently, two reports suggested that generally destination memory should be poorer than source memory, and that it should be particularly difficult for older people. We tested these predictions by having young and older participants read sentences to two examiners (destination encoding) and listen to sentences read by two examiners (source encoding), under intentional (Experiment 1) or incidental encoding (Experiments 2 and 3). Only in Experiment 3 (in which cognitive demands during destination encoding were increased) was destination memory significantly poorer than source memory. In none of the experiments were older adults inferior to the young on destination or source memory. Destination- and source-memory scores were significantly correlated. Item memory was consistently superior for sentences that had been read out loud (during destination encoding) versus those that had been heard (during source encoding). Destination memory needs not always be poorer than source memory, appears not to be particularly impaired by normal ageing and may depend on similar processes to those supporting source memory.     

The effect of old age on supra-span learning of visuo-spatial sequences under incidental and intentional encoding instructions

Recent findings [Turcotte, Gagnon, & Poirier, 2005. The effect of old age on the learning of supra-span sequences. Psychology and Aging, 20, 251-260.] indicate that incidental learning of visuo-spatial supra-span sequences through immediate serial recall declines with old age (Hebb's paradigm). In this study, we examined whether strategies induced by awareness of the repeated sequence might explain age differences. Young (18-35 years old) and older (65-80 years old) participants underwent either incidental or intentional learning instructions. Results indicated that older adults demonstrated reduced learning of the repeated sequence under both incidental and intentional instructions. In comparison, young adults showed superior learning of the repeated sequence in both conditions but intentional instructions triggered faster and greater learning in this age group. The results strongly indicated that knowledge of the repeated sequence enhanced learning only in the group of young adults. Older adults were unable to translate the knowledge of the repetition into elaborate strategies that would increase recall of the repeated sequence. Other findings suggest that incidental learning in young adults was mediated by both non-conscious and conscious recollection processes.     

Older adults show a self-reference effect for narrative information

The self-reference effect (SRE), enhanced memory for information encoded through self-related processing, has been established in younger and older adults using single trait adjective words. We sought to examine the generality of this phenomenon by studying narrative information in these populations. Additionally, we investigated retrieval experience at recognition and whether valence of stimuli influences memory differently in young and older adults. Participants encoded trait adjectives and narratives in self-reference, semantic, or structural processing conditions, followed by tests of recall and recognition. Experiment 1 revealed an SRE for trait adjective recognition and narrative cued recall in both age groups, although the existence of an SRE for narrative recognition was unclear due to ceiling effects. Experiment 2 revealed an SRE on an adapted test of narrative recognition. Self-referential encoding was shown to enhance recollection for both trait adjectives and narrative material in Experiment 1, whereas similar estimates of recollection for self-reference and semantic conditions were found in Experiment 2. Valence effects were inconsistent but generally similar in young and older adults when they were found. Results demonstrate that the self-reference technique extends to narrative information in young and older adults and may provide a valuable intervention tool for those experiencing age-related memory decline.     

Stronger evidence for own-age effects in memory for older as compared to younger adults

Three studies examined whether younger and older adults better recall information associated with their own than information related to another age group. All studies compared young and older adults with respect to incidental memory for previously presented stimuli (Studies 1 and 2: everyday objects; Study 3: vacation advertisements) that had been randomly paired with an age-related cue (e.g., photo of a young or an old person; the word "young" or "old"). All three studies found the expected interaction of participants' age and age-associated information. Studies 1 and 2 showed that the memory bias for information arbitrarily associated with one's own as compared to another age group was significant for older adults only. However, when age-relevance was introduced in a context of equal importance to younger and older adults (information about vacations paired either with pictures of young or older adults), the memory bias for one's own age group was clearly present for both younger and older adults (Study 3).     

The bizarreness effect: Dissociation between item and source memory

The present study investigated the relationship between memory for particular items (nouns embedded in sentences) varying in bizarreness and the spatial location in which they were learned. Consistent with earlier findings, the items embedded in bizarre sentences were better recalled than those embedded in common sentences. This mnemonic advantage for bizarre sentences did not extend to memory for source (spatial location), which did not reliably vary as a function of bizarreness. This pattern is inconsistent with several existing theoretical formulations of the relation between item and source encoding and related findings. We propose a theoretical possibility for integrating these varied findings. Finally, the expectation-violation explanation of the bizarreness effect was not supported by the absence of a relation between recall of the items and memory for context.     

The bizarreness effect: dissociation between item and source memory

The present study investigated the relationship between memory for particular items (nouns embedded in sentences) varying in bizarreness and the spatial location in which they were learned. Consistent with earlier findings, the items embedded in bizarre sentences were better recalled than those embedded in common sentences. This mnemonic advantage for bizarre sentences did not extend to memory for source (spatial location), which did not reliably vary as a function of bizarreness. This pattern is inconsistent with several existing theoretical formulations of the relation between item and source encoding and related findings. We propose a theoretical possibility for integrating these varied findings. Finally, the expectation-violation explanation of the bizarreness effect was not supported by the absence of a relation between recall of the items and memory for context.     

Relationships between personality variables and bizarreness effects in free recall

Relationships between 6 personality variables and each of 3 different measures of recall for bizarre and common sentences were examined. The personality variables investigated included measures of sensation seeking, novelty experiencing, desire for novelty, arousal-seeking tendency, social potency, and conservatism. Recall was measured in terms of sentences accessed, target words recovered per accessed sentence, and misplaced target words. The results indicated the typical pattern of bizarreness effects on recall and significant relationships between personality variables and these effects. Arousal seeking and conservatism were positively related to a bizarreness advantage in sentences accessed. Additionally, high social potency was related to the recovery of more details from common than bizarre sentences, and high desire for novelty was related to a greater bizarre misplacement effect. The results are discussed in terms of orienting and defensive responses to bizarreness.     

Memory for common and bizarre stimuli: A storage-retrieval analysis

We tested the hypothesis that common stimuli are stored in memory better than bizarre stimuli are. Subjects memorized a series of noun pairs embedded within 20 common or bizarre sentences. By using a between-list design, free and cued recall, and intentional-learning instructions, we were able to obtain a commonness effect (i.e., a recall advantage for the common sentences). Riefer and Rouder’s (1992) multinomial processing-tree model for measuring storage and retrieval was applied to the data, which revealed that the recall advantage for common sentences was due to storage and not retrieval processes. We propose a two-factor theory: that common items are stored better in memory, but that bizarre items are retrieved better from memory. This storage-retrieval explanation does a good job of accounting for a number of findings associated with the bizarreness effect.     

Stronger evidence for own-age effects in memory for older as compared to younger adults

Three studies examined whether younger and older adults better recall information associated with their own than information related to another age group. All studies compared young and older adults with respect to incidental memory for previously presented stimuli (Studies 1 and 2: everyday objects; Study 3: vacation advertisements) that had been randomly paired with an age-related cue (e.g., photo of a young or an old person; the word “young” or “old”). All three studies found the expected interaction of participants’ age and age-associated information. Studies 1 and 2 showed that the memory bias for information arbitrarily associated with one's own as compared to another age group was significant for older adults only. However, when age-relevance was introduced in a context of equal importance to younger and older adults (information about vacations paired either with pictures of young or older adults), the memory bias for one's own age group was clearly present for both younger and older adults (Study 3).