Semantic False Memories Research Articles

Comparison of semantic and phonological false memories in short- and long-term tests.

The Deese-Roediger-McDermott (DRM) paradigm has been at the centre of false memory research. Whereas most work with this paradigm has examined memory at the long term and with semantically associated lists, the present study examines phonological and semantic false memories at both short- and long-term delays. In two experiments, participants studied short lists containing six (Experiment 1) or four (Experiment 2) items, either semantically or phonologically related to the same non-studied critical items (CI). Following each list, participants completed 36 trials of an immediate recognition task (short-term memory [STM]-only condition) only or they also completed a surprise recognition test after a 1-min delay after all 36 STM trials (STM + long-term memory [LTM] condition). In STM, false alarms were higher in phonological lists, whereas after the delay, false alarms were higher in semantic lists, reflecting differential sensitivity to the type of association as a function of delay. A third experiment examined LTM performance after controlling for prior testing and yielded highly similar results. Both the activation-monitoring framework (AMF) and fuzzy-trace theory (FTT) can explain the majority of the findings, with some remaining issues. These results confirm that information from the knowledge base (LTM) does influence accuracy in an STM task, albeit less so than perceptual level similarity.

Sleep influences neural representations of true and false memories: An event-related potential study

Episodic memory is reconstructive and is thus prone to false memory formation. Although false memories are proposed to develop via associative processes, the nature of their neural representations, and the effect of sleep on false memory processing is currently unclear. The present research employed the Deese-Roediger-McDermott (DRM) paradigm and a daytime nap to determine whether semantic false memories and true memories could be differentiated using event-related potentials (ERPs). We also sought to illuminate the role of sleep in memory formation and learning. Healthy participants (N = 34, 28F, mean age = 23.23, range = 18–33) completed the learning phase of the DRM task followed by an immediate and a delayed recognition phase. The two recognition phases were separated by either a 2hr daytime nap or an equivalent wake period. Linear mixed modelling of effects at delayed recognition revealed larger LPC amplitudes for true memories in contrast to false memories for those in the wake group, and larger P300 amplitudes for false compared to true memories across sleep and wake groups. Larger LPC amplitudes for true memories were associated with enhanced true memory recognition following sleep, whilst larger P300 amplitudes were associated with similar true and false memory recognition rates. These findings are argued to reflect sleep’s ability to promote memory generalisation associated with pattern completion, whilst also enhancing true memory recognition when memory traces have a strong episodic basis (linked to pattern separation). The present research suggests that true and false memories have differing neural profiles and are reflective of adaptive memory processes.

Semantic representations in the temporal pole predict false memories

Recent advances in neuroscience have given us unprecedented insight into the neural mechanisms of false memory, showing that artificial memories can be inserted into the memory cells of the hippocampus in a way that is indistinguishable from true memories. However, this alone is not enough to explain how false memories can arise naturally in the course of our daily lives. Cognitive psychology has demonstrated that many instances of false memory, both in the laboratory and the real world, can be attributed to semantic interference. Whereas previous studies have found that a diverse set of regions show some involvement in semantic false memory, none have revealed the nature of the semantic representations underpinning the phenomenon. Here we use fMRI with representational similarity analysis to search for a neural code consistent with semantic false memory. We find clear evidence that false memories emerge from a similarity-based neural code in the temporal pole, a region that has been called the "semantic hub" of the brain. We further show that each individual has a partially unique semantic code within the temporal pole, and this unique code can predict idiosyncratic patterns of memory errors. Finally, we show that the same neural code can also predict variation in true-memory performance, consistent with an adaptive perspective on false memory. Taken together, our findings reveal the underlying structure of neural representations of semantic knowledge, and how this semantic structure can both enhance and distort our memories.

False memory susceptibility is correlated with categorisation ability in humans

Our memory is often surprisingly inaccurate, with errors ranging from misremembering minor details of events to generating illusory memories of entire episodes. The pervasiveness of such false memories generates a puzzle: in the face of selection pressure for accuracy of memory, how could such systematic failures have persisted over evolutionary time? It is possible that memory errors are an inevitable by-product of our adaptive memories and that semantic false memories are specifically connected to our ability to learn rules and concepts and to classify objects by category memberships. Here we test this possibility using a standard experimental false memory paradigm and inter-individual variation in verbal categorisation ability. Indeed it turns out that the error scores are significantly negatively correlated, with those individuals scoring fewer errors on the categorisation test being more susceptible to false memory intrusions in a free recall test. A similar trend, though not significant, was observed between individual categorisation ability and false memory susceptibility in a word recognition task. Our results therefore indicate that false memories, to some extent, might be a by-product of our ability to learn rules, categories and concepts.

False memory susceptibility is correlated with categorisation ability in humans.

Our memory is often surprisingly inaccurate, with errors ranging from misremembering minor details of events to generating illusory memories of entire episodes. The pervasiveness of such false memories generates a puzzle: in the face of selection pressure for accuracy of memory, how could such systematic failures have persisted over evolutionary time? It is possible that memory errors are an inevitable by-product of our adaptive memories and that semantic false memories are specifically connected to our ability to learn rules and concepts and to classify objects by category memberships. Here we test this possibility using a standard experimental false memory paradigm and inter-individual variation in verbal categorisation ability. Indeed it turns out that the error scores are significantly negatively correlated, with those individuals scoring fewer errors on the categorisation test being more susceptible to false memory intrusions in a free recall test. A similar trend, though not significant, was observed between individual categorisation ability and false memory susceptibility in a word recognition task. Our results therefore indicate that false memories, to some extent, might be a by-product of our ability to learn rules, categories and concepts.

False memory susceptibility is correlated with categorisation ability in humans.

Our memory is often surprisingly inaccurate, with errors ranging from misremembering minor details of events to generating illusory memories of entire episodes. The pervasiveness of such false memories generates a puzzle: in the face of selection pressure for accuracy of memory, how could such systematic failures have persisted over evolutionary time? It is possible that memory errors are an inevitable by-product of our adaptive memories and that semantic false memories are specifically connected to our ability to learn rules and concepts and to classify objects by category memberships. Here we test this possibility using a standard experimental false memory paradigm and inter-individual variation in verbal categorisation ability. Indeed it turns out that the error scores are significantly negatively correlated, with those individuals scoring fewer errors on the categorisation test being more susceptible to false memory intrusions in a free recall test. A similar trend, though not significant, was observed between individual categorisation ability and false memory susceptibility in a word recognition task. Our results therefore indicate that false memories, to some extent, might be a by-product of our ability to learn rules, categories and concepts.

Partial Contextual Control of Semantic False Memories in the Form of Derived Relational Intrusions Following Training

A modified version of the original Derived Relational Intrusions Following Training paradigm (DRIFT; Guinther & Dougher, Journal of the Experimental Analysis of Behavior, 93, 329–347; 2010) was used in an attempt to engineer contextually controlled semantic false memories. Participants completed a contextually controlled interrelated conditional discrimination training procedure (match to sample) without tests of symmetry or transitivity. Study list words were nominally assigned to participate in a functional equivalence class with 1 set of non-study words in 1 context but with a different set of non-study words in a different context. The study list words were then presented in 1 of the 2 contexts, between subjects, for free-recall memory testing. Subsequent transfer of the study list words’ remembering function to non-study words (i.e., false recall) was found to be partially dependent upon the context in which the free recall test was administered, thus demonstrating partial contextual control of semantic false memory.

Overdistribution in source memory.

Semantic false memories are confounded with a second type of error, overdistribution, in which items are attributed to contradictory episodic states. Overdistribution errors have proved to be more common than false memories when the 2 are disentangled. We investigated whether overdistribution is prevalent in another classic false memory paradigm: source monitoring. It is. Conventional false memory responses (source misattributions) were predominantly overdistribution errors, but unlike semantic false memory, overdistribution also accounted for more than half of true memory responses (correct source attributions). Experimental control of overdistribution was achieved via a series of manipulations that affected either recollection of contextual details or item memory (concreteness, frequency, list order, number of presentation contexts, and individual differences in verbatim memory). A theoretical model was used to analyze the data (conjoint process dissociation) that predicts that (a) overdistribution is directly proportional to item memory but inversely proportional to recollection and (b) item memory is not a necessary precondition for recollection of contextual details. The results were consistent with both predictions.

Phonological false memories in children and adults: Evidence for a developmental reversal

False memories created by the Deese/Roediger–McDermott (DRM) procedure typically show a developmental reversal whereby levels of false recall increase with age. In contrast, false memories produced by phonological lists have been shown to decrease as age increases. In the current study we show that phonological false memories, like semantic false memories produced by the DRM procedure, show a developmental reversal when list items converge on a single critical lure. In addition, effects of list length were observed in adults and older children but not in the younger children, again mirroring effects previously observed in semantic false memories. These findings suggest that differences in list structure underlie the divergent developmental trajectories previously reported in semantic and phonological false memories. The findings are discussed in relation to theories of false memory and theories of spoken word recognition.

Test-induced priming increases false recognition in older but not younger children

The effect of test-induced priming on false recognition was investigated in children aged 5, 7, 9, and 11 years using lists of semantic associates, category exemplars, and phonological associates. In line with effects previously observed in adults, nine- and eleven-year-olds showed increased levels of false recognition when critical lures were preceded by four studied items. This pattern was present with all three list types. In contrast, no effects of test-induced priming were observed in five- or seven-year-olds with any list type. The results also support those of previous studies in showing a developmental shift from phonological to semantic false memories. The findings are discussed in terms of current theories of children’s false memories.

Semantic false memories in the form of derived relational intrusions following training.

Contemporary behavior analytic research is making headway in characterizing memory phenomena that typically have been characterized by cognitive models, and the current study extends this development by producing "false memories" in the form of functional equivalence responding. A match-to-sample training procedure was administered in order to encourage participants to treat groups of unrelated English words as being interchangeable. Following training, participants were presented with a list of words from within one of the groups for a free recall test and a recognition test. Results showed that participants were more likely to falsely recall and recognize words that had been assigned to the same group as the list words during prior training, relative to words not assigned to the same group and relative to words that co-occurred with list words. These results indicate that semantic relatedness can be experimentally manipulated in order to produce specific false memories.

Dissociated developmental trajectories for semantic and phonological false memories

False recognition following presentation of semantically related and phonologically related word lists was evaluated in 8-, 11-, and 13-year-olds. Children heard lists of words that were either semantic (e.g., bed, rest, wake …) or phonological associates (e.g., pole, bowl, hole …) of a critical unpresented word (e.g., sleep, roll), respectively. A semantic false memory was defined as false recognition of a semantically related but unpresented word. A phonological false memory was defined as false recognition of a phonologically related but unpresented word. False memories in the two tasks showed opposite developmental trends, increasing with age for semantic relatedness and decreasing with age for phonological relatedness.

Toward a frontal lobe disconnection model of deep dyslexia: The role of semantic feedback in phonological false memories

We use a false memory paradigm to investigate the extent to which phonologically relations of a target word may be implicated in semantically driven access of that target word. We are specifically interested in understanding how access to orthography may limit the scope of this implication. Our interest in these questions is directly motivated by the claim that the probability of deep dyslexics making a semantic error in reading a word is affected by the number of close phonological relations of the word (Buchanan, L., Hildebrandt, N., & MacKinnon, G. E. (1994). Phonological processing of non-words by a deep dyslexic patient: A rowse is implicitly a rose. Journal of Neurolinguistics, 8, 163–181; Buchanan, L., Hildebrandt, N., & MacKinnon, G. E. (1996). Phonological processing of non-words in deep dyslexia: Typical and independent? Journal of Neurolinguistics, 9, 113–133). We use the study list in a false memory paradigm to semantically prime words. We look for false recognition effects among phonological relations of the semantically primed words in both modalities, with and without simultaneous orthographic overlap. The critical lures of interest in the experiments are words that are related by orthographic or phonological overlap to the unseen semantic target. We found increased false recognition rates for phonological associates of the unseen semantically-primed target in the auditory modality, only among words with no orthographic overlap with the unseen semantically-primed target. The locus of overlap and the phonological neighborhood size of the phonological relation also plays a role in the false memory rate. In a related experiment, we showed that the phonological neighborhood and concreteness of critical lures also mediates the probability of a semantic false memory. These results are discussed with respect to a frontal lobe disconnection theory of deep dyslexia, which posits that semantic errors in deep dyslexia are result from impoverished constraints to prefrontal regions that are implicated in semantic and phonological access of written words.

Recollection rejection: false-memory editing in children and adults.

Mechanisms for editing false events out of memory reports have fundamental implications for theories of false memory and for best practice in applied domains in which false reports must be minimized (e.g., forensic psychological interviews, sworn testimony). A mechanism posited in fuzzy-trace theory, recollection rejection, is considered. A process analysis of false-memory editing is presented, which assumes that false-but-gist-consistent events (e.g., the word SOFA, when the word COUCH was experienced) sometimes cue the retrieval of verbatim traces of the corresponding true events (COUCH), generating mismatches that counteract the high familiarity of false-but-gist-consistent events. Empirical support comes from 2 qualitative phenomena: recollective suppression of semantic false memory and inverted-U relations between retrieval time and semantic false memory. Further support comes from 2 quantitative methodologies: conjoint recognition and receiver operating characteristics. The analysis also predicts a novel false-memory phenomenon (erroneous recollection rejection), in which true events are inappropriately edited out of memory reports.