Paws + cause = pause? Memory load and memory blends in homophone recognition

Previous research has shown that separate information sources, activated closely together in time, can induce errors suggestive of memory blends. In Experiment 1, homophones were used to induce such memory errors. In a study task, participants made relatedness judgments to word pairs that included homophones (e.g., PAWS-BEAR). During this task, one group (study-similar) maintained memory loads with words that were orthographically similar to the presented homophones (e.g., JAWS). Another group (test-similar) maintained memory loads similar to those obtained for the study homophone's alternate spelling (e.g., CAUSE). A third group maintained no memory load during the task. In a surprise recognition test, participants were presented both previously viewed homophones (PAWS) and non-presented alternate spellings (PAUSE). We hypothesized that partially activated alternate spellings, in conjunction with the orthographically similar memory words, would result in the creation of blended memories. The results followed suit: The test-similar condition produced significantly elevated false alarms, relative to both the study-similar and the no-load conditions. Experiment 2 replicated these results while including memory loads to control for potential orthographic confusions. The findings are discussed in terms of multiple, episodic memories later activated as single, blended memories.     

False memory and importance: Can we prioritize encoding without consequence?

Given the large amount of information that we encounter, we often must prioritize what information we attempt to remember. Although critical for everyday functioning, relatively little research has focused on how people prioritize the encoding of information. Recent research has shown that people can and do selectively remember information assigned with higher, relative to lower, importance. However, the mechanisms underlying this prioritization process and the consequences of these processes are still not well understood. In the present study, we sought to better understand these prioritization processes and whether implementing these processes comes at the cost of memory accuracy, by increasing false memories. We used a modified form of the Deese/Roediger–McDermott (DRM) paradigm, in which participants studied DRM lists, with each list paired with low, medium, or high point values. In Experiment 1, encoding higher values led to more false memories than did encoding lower values, possibly because prioritizing information enhanced relational processing among high-value words. In Experiment 2, disrupting relational processing selectively reduced false memories for high-value words. Finally, in Experiment 3, facilitating relational processing selectively increased false memories for low-value words. These findings suggest that while prioritizing information can enhance true memory, this process concomitantly increases false memories. Furthermore, the mechanism underlying these prioritization processes depends on the ability to successfully engage in relational processing. Thus, how we prioritize the encoding of incoming information can come at a cost in terms of accurate memory.     

Structure and strategy in the associative false memory paradigm

List-learning experiments can have several levels of structure: individual words, the gist (if any) of each list, and the task in which those lists are embedded. The usual presentation of the DRM associative paradigm (Deese, 1959; Roediger & McDermott, 1995) strongly encourages a focus on gist and produces a high rate of false recall of key words (FRK). The experiments reported here were designed to invite the use of memory strategies based on structures other than the gist and thus reduce FRK. The crucial condition of Experiment 1, short lists followed by rehearsal, encouraged a focus on individual words and produced a low rate of FRK. In Experiment 2, the lists were embedded in a guessing game, which virtually eliminated FRK. FRK was also low in Experiments 3a and 3b when participants engaged in a complex task involving the first letters of list words. The relevance of these findings to false memories in the DRM and the connection of false autobiographical memories is discussed.     

Incidental and intentional visual memory: What memories are and are not affected by encoding tasks?

Prior research into the impact of encoding tasks on visual memory (Castelhano & Henderson, 2005) indicated that incidental and intentional encoding tasks led to similar memory performance. The current study investigated whether different encoding tasks impacted visual memories equally for all types of objects in a conjunction search (e.g., targets, colour distractors, object category distractors, or distractors unrelated to the target). In sequences of pictures, participants searched for prespecified targets (e.g., green apple; Experiment 1), memorized all objects (Experiment 2), searched for specified targets while memorizing all objects (Experiment 3), searched for postidentified targets (Experiment 4), or memorized all objects with one object prespecified (Experiment 5). Encoding task significantly improved visual memory for targets and led to worse memory for unrelated distractors, but did not influence visual memory of distractors that were related to the target's colour or object category. The differential influence of encoding task indicates that the relative importance of the object both positively and negatively influences the memory retained.     

Comparison of activation level between true and false items in the DRM paradigm

The aim of the present study was to compare the activation levels of true and false memories in the Deese–Roediger–McDermott (DRM) paradigm. For this purpose, we used a lexical decision task (LDT) that can be considered a relative pure measure of activation. Participants had to study a list of words that were semantically associated to a critical non-presented word (CI), and afterwards had to classify the actually studied words, the CI and new words in the LDT. Results indicated that the classification latency of the CI was the same as actually studied words and shorter than new words. The results might be interpreted as evidence that the false and true memory items have the same activation level and that the false memory effect can be based on the indirect activation of the CI at the encoding.     

Variations in processing resources and resistance to false memories in younger and older adults

The influence of available processing resources on the resistance to false memories (FMs) for lists of semantically related items associated with a non-presented critical lure was examined in younger and older adults. Reducing the available resources at encoding in younger adults (Experiments 1 and 2) led to a performance similar to that of older adults (i.e., higher rates of FMs in addition to reduced rates of correct recall). However, increasing the available resources (Experiments 2 and 3) led to improvements in the rates of correct recall in both age groups and decreased the probability of FMs in younger adults, although warnings had to be added in older adults to obtain similar effects on FMs. Parallel influences on a post-recall test asking participants to report items that they had thought of but did not recall were also found. The influence of available cognitive resources for memory accuracy is also discussed with respect to activation-monitoring (e.g., McDermott & Watson, 2001) and fuzzy-trace (e.g., Brainerd & Reyna, 2002) accounts of age-related increased in false memories.     

Are covert verbal responses mediating false implicit memory?

In the DRM paradigm, illusory memories of a nonpresented word can be induced by the presentation of strong associates to this word. In two experiments, we explored previous findings of false implicit memory of the nonpresented words (McDermott, 1997; McKone & Murphy, 2000). Experiment 1 extended the finding of false priming to the anagram task. Furthermore, participants attributed this "false" influence on performance to the difficulty of the anagrams and judged them as easier to solve for other students. In Experiment 2, articulatory suppression during the study of the associates resulted in nonsignificant levels of false priming, whereas the normal priming effect was in the same range as that observed in Experiment 1. The study replicates and extends findings of false implicit memory to the anagram task and suggests that future studies should examine the role of covert verbal responses in producing false implicit memory.     

Creating false memories for brand names

Using the Deese–Roediger–McDermott (DRM) paradigm, participants are presented with lists of associated words (e.g., bed, awake, night etc). Subsequently, they reliably have false memories for related but non‐presented words (e.g. SLEEP). The present study investigated whether false memories could be created for brand names (e.g. Morrisons, Sainsbury's, Waitrose and TESCO) using the DRM paradigm and whether the effect was reduced if stimuli were presented in brand appropriate fonts compared with a plain font. Participants were presented with lists of brand names in plain or brand appropriate fonts, followed by a distractor task or free recall. Finally, they had a recognition task. Both false recall and false recognition of non‐presented brand names occurred. Brand specific fonts at study had no effect on recall but increased overall recognition. There was considerable variability in levels of false recall and false recognition amongst lists and across participants and reasons for this are discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Creating False Memories of Words with or without Recognition of List Items: Evidence for Nonconscious Processes

Subjects exposed to lists of semantically related words falsely remember nonstudied words that are associated with the list items (e.g., Deese, 1959; Roediger & McDermott, 1995). To determine if subjects would demonstrate this false memory effect if they were unable to recognize the list items, we presented lists of semantically related words with or without a concurrent memory load at rates of 2 s, 250 ms, or 20 ms per word (Experiment 1, between-subjects design) and 2 s or 20 ms per word (Experiment 2, within-subjects design). We found that the subjects falsely recognized semantically related nonstudied words in all conditions, even when they were unable to discriminate studied words from unrelated nonstudied words. Recognition of list items was unnecessary for the occurrence of the false memory effect. This finding suggests that this memory illusion can be based on the nonconscious activation of semantic concepts during list presentation.     

Not lost in translation: writing auditorily presented words at study increases correct recognition “at no cost”

Previous studies have reported a translation effect in memory, whereby encoding tasks that involve translating between processing domains produce a memory advantage relative to tasks that involve a single domain. We investigated the effects of translation on true and false memories using the Deese/Roediger-McDermott (DRM) procedure [Deese, J. (1959). On the prediction of occurrence of particular verbal intrusions in immediate recall. Journal of Experimental Psychology, 58, 17–22; Roediger, H. L., III, & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, & Cognition, 21, 803–814]. Translation between modalities enhanced correct recognition but had no effect on false recognition. Results are consistent with previous research showing that correct memory can be enhanced “at no cost” in terms of accuracy. Findings are discussed in terms of understanding the relationship between true and false memories produced by the DRM procedure.     

False memory in a short-term memory task

The Deese/Roediger-McDermott (DRM; Roediger & McDermott, 1995) paradigm reliably elicits false memories for critical nonpresented words in recognition tasks. The present studies used a Sternberg (1966) task with DRM lists to determine whether false memories occur in short-term memory tasks and to assess the contribution of latency data in the measurement of false memories. Subjects studied three, five, or seven items from DRM lists and responded to a single probe (studied or nonstudied). In both experiments, critical lures were falsely recognized more often than nonpresented weak associates. Latency data indicated that correct rejections of critical lures were slower than correct rejections of weakly related items at all set sizes. False alarms to critical lures were slower than hits to list items. Latency data can distinguish veridical and false memories in a short-term memory task. Results are discussed in terms of activation-monitoring models of false memory.     

False memories and fantastic beliefs: 15 years of the DRM illusion

This article reviews research using the Deese/Roediger—McDermott (DRM) associative memory illusion, whereby people falsely remember words that were not presented. This illusion has broadly influenced basic theories of memory in cognitive psychology and neuroscience and naturally raises the question as to how these theories apply to more complex autobiographical memories. Some applicability is evident from research linking individual differences in the DRM illusion to false autobiographical memories (e.g., misremembering public events) and fantastic autobiographical beliefs (e.g., memories from past lives). But which aspects generalize? Here it is argued that a process—oriented approach is needed in order to answer this question. Many productive years of DRM research indicate that multiple and often opposing psychological processes cause even the most basic false memories. In light of these discoveries, more researchers need to use methods that isolate these component processes if the goal is to understand false memories both in the lab and in life.     

The effect of warnings on false memories in young and older adults

In the present experiments, we examined adult age differences in the ability to suppress false memories, using the Deese-Roediger-McDermott (DRM) paradigm (Deese, 1959; Roediger & McDermott, 1995). Participants studied lists of words (e.g., bed, rest, awake, etc.), each related to a nonpresented critical lure word (e.g., sleep). Typically, recognition tests reveal false alarms to critical lures at rates comparable to those for hits for studied words. In two experiments, separate groups of young and older adults were unwarned about the false memory effect, warned before studying the lists, or warned after study and before test. Lists were presented at either a slow rate (4 sec/word) or a faster rate (2 sec/word). Young adults were better able to discriminate between studied words and critical lures when warned about the DRM effect either before study or after study but before retrieval, and their performance improved with a slower presentation rate. Older adults were able to discriminate between studied words and critical lures when given warnings before study, but not when given warnings after study but before retrieval. Performance on a working memory capacity measure predicted false recognition following study and retrieval warnings. The results suggest that effective use of warnings to reduce false memories is contingent on the quality and type of encoded information, as well as on whether that information is accessed at retrieval. Furthermore, discriminating between similar sources of activation is dependent on working memory capacity, which declines with advancing age.     

An investigation of false memory in perceptual implicit tasks

Reports of critical lure priming in perceptual implicit tasks [e.g., McKone, E., & Murphy, B. (2000). Implicit false memory: Effects of modality and multiple study presentations on long-lived semantic priming. Journal of Memory and Language, 43, 89-109] using the Deese-Roediger-McDermott [Roediger, H. L., III, & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803-814] procedure have suggested availability of the lexical form of lure items at study. Three experiments were conducted to further explore "false" implicit priming in perceptual tests. In Experiments 1 and 3, implicit and explicit stem completion tests were given in the DRM procedure with semantic lists; in Experiment 2, a graphemic response test was used in a similar design. For all experiments, explicit instructions resulted in reliable false memory, while implicit instructions resulted in priming for list items and no priming for lure items. Priming for lure items was evident for "test-aware" subjects only in Experiment 1 and in a combined analysis for all three experiments. These results establish boundary conditions for priming for critical lures and indicate that access to the lexical form of critical lures may not occur under incidental learning conditions when strong controls against explicit retrieval are implemented.     

Evidence that nonconscious processes are sufficient to produce false memories

Are nonconscious processes sufficient to cause false memories of a nonstudied event? To investigate this issue, we controlled and measured conscious processing in the DRM task, in which studying associates (e.g., bed, rest, awake...) causes false memories of nonstudied associates (e.g., sleep). During the study phase, subjects studied visually masked associates at extremely rapid rates, followed by immediate recall. After this initial phase, nonstudied test words were rapidly presented for perceptual identification, followed by recognition memory judgments. On the perceptual identification task, we found significant priming of nonstudied associates, relative to control words. We also found significant false recognition of these nonstudied associates, even when subjects did not recall this word at study or identify it at test, indicating that nonconscious processes can cause false recognition. These recognition effects were found immediately after studying each list of associates, but not on a delayed test that occurred after the presentation of several intervening lists. Nonconscious processes are sufficient to cause this memory illusion on immediate tests, but may be insufficient for more vivid and lasting false memories.     

Reinstatement of odour context cues veridical memories but not false memories

ABSTRACT

The sense of smell has made a recent return to the forefront of research on episodic memory. Odour context cues can reactivate recently encoded memories during sleep-dependent memory consolidation [e.g., Rasch, B., Buchel, C., Gais, S., & Born, J. (2007). Odor cues during slow-wave sleep prompt declarative memory consolidation. Science, 315, 1426–1429], and reinstating the odour experienced during encoding at test results in superior recall and recognition [e.g., Isarida, T., Sakai, T., Kubota, T., Koga, M., Katayama, Y., & Isarida, T. K. (2014). Odor-context effects in free recall after a short retention interval: A new methodology for controlling adaptation. Memory & Cognition, 42, 421–433]. However, whether the impact of odour cues is restricted to the specific memories studied in the presence of the odour, or whether reinstating the odour also cues unstudied memories that are semantically related to the studied memories (i.e., false memories) is unknown. We used the Deese-Roediger-McDermott false memory paradigm to quantify the impact of odour cues on both veridical memory and false memory. Reinstating the odour presented during the study of the DRM word lists at the test phase resulted in better free recall of the studied words, but had no statistically significant impact on the number of false memories produced. We argue that odour cues influence recall of the memories they co-occurred with during study but potentially not semantically related memories.     

Depth of processing and memory organization

Summary The study examined the idea that the organization of information in memory varies depending on the depth of processing during input, as well as on the conditions for retrieval. Two types of memory organization are distinguished: Conceptual organization implies a hierarchical structure in which items are grouped according to a principled taxonomic system (e.g., cow — horse). Associative organization, in contrast, is based on direct links among the members of a group (e.g., cow — milk). Two experiments examined the propositions that conceptual relations require more effort to be encoded during learning and more effort to be utilized during remenbering than associative relations. In Experiment 1 a list of 28 words was used, which could be grouped into 14 conceptual categories or, alternatively, into 14 associative categories of two words each. The words were presented under either shallow or deep encoding conditions. Increased depth of encoding resulted in increased conceptual clustering but had little effect on amount of associative clustering. Similar amounts of associative and conceptual clustering were observed during early output positions, but conceptual clustering tended to increase with recall trials, suggesting that it might depend on the establishment of a retrieval schema. In Experiment 2, after memorizing a list of words, subjects recalled the words either with or without the requirement to perform a secondary task while recalling. Relative to the undisturbed recall condition, the secondary task condition indicated stronger associative than conceptual clustering. The results were seen to support the idea that different types of memory organization may become salient under different attentional conditions.     

Underestimation of prior remembering and susceptibility to false memories: two sides of the same coin?

In two studies, we explored whether susceptibility to false memories and the underestimation of prior memories (i.e., forgot-it-all-along effect) tap overlapping memory phenomena. Study 1 investigated this issue by administering the Deese/Roediger–McDermott task (DRM) and the forgot-it-all-along (FIA) task to an undergraduate sample (N = 110). It was furthermore explored how performances on these tasks correlate with clinically relevant traits such as fantasy proneness, dissociative experiences, and cognitive efficiency. Results show that FIA and DRM performances are relatively independent from each other, suggesting that these measures empirically apparently refer to separate dimensions. However, they do not seem to define different profiles in terms of dissociation, fantasy proneness, and cognitive efficiency. Study 2 replicated the finding of relative independence between false memory propensity (as measured with the DRM task) and the underestimation of prior memories (as measured with an autobiographical memory dating task) in people with a history of childhood sexual abuse (N = 35).     

Revisiting the rise and fall of false recall: Presentation rate effects depend on retention interval

Leading theories of false memory predict that veridical and false recall of lists of semantically associated words can be dissociated by varying the presentation speed during study. Specifically, as presentation rate increases from milliseconds to seconds, veridical recall is predicted to increase monotonically while false recall is predicted to show a rapid rise and then a slow decrease—a pattern shown by McDermott and Watson (2001) in a study using immediate recall tests. In three experiments we tested the generality of the effects of rapid presentation rates on veridical and false memory. In Experiments 1 and 2 participants exhibited high levels of false recall on a delayed recall test, even for very fast stimulus onset asynchronies (SOA)—contrary to predictions from leading theories of false memory. When we switched to an immediate recall test in Experiment 3 we replicated the pattern predicted by the theories and observed by McDermott and Watson. Follow-up analyses further showed that the relative output position of false recalls is not affected by presentation rate, contrary to predictions from fuzzy trace theory. Implications for theories of false memory, including activation monitoring theory and fuzzy trace theory, are discussed.     

What is the connection between true and false memories? The differential roles of interitem associations in recall and recognition.

Veridical memory for presented list words and false memory for nonpresented but related items were tested using the Deese/Roediger and McDermott paradigm. The strength and density of preexisting connections among the list words, and from the list words to the critical items, were manipulated. The likelihood of producing false memories in free recall varied with the strength of connections from the list words to the critical items but was inversely related to the density of the interconnections among the list words. In contrast, veridical recall of list words was positively related to the density of the interconnections. A final recognition test showed that both false and veridical memories were more likely when the list words were more densely interconnected. The results are discussed in terms of an associative model of memory, Processing Implicit and Explicit Representations (PIER 2) that describes the influence of implicitly activated preexisting information on memory performance.