Measuring Source Memory

Findings reported in the memory literature suggest that the emotional components of an encoding episode can be dissociated from nonemotional memory. In particular, it has been found that the previous association with threatening events can be retrieved in aversive conditioning even in the absence of item identification. In the present study, we test whether emotional source memory can be independent of item recognition. Participants saw pictures of snakes paired with threatening and nonthreatening context information (poisonousness or nonpoisonousness). In the source memory test, participants were required to remember whether a snake was associated with poisonousness or nonpoisonousness. A simple extension of a well-established multinomial source monitoring model was used to measure source memory for unrecognized items. By using this model, it was possible to assess directly whether participants were able to associate a previously seen snake with poisonousness or nonpoisonousness even if the snake itself was not recognized as having been presented during the experiment. In 3 experiments, emotional source memory was only found for recognized items. While source memory for recognized items differed between emotional and nonemotional information, source memory for unrecognized items was equally absent for emotional and nonemotional information. We conclude that emotional context information is bound to item representations and cannot be retrieved in the absence of item recognition. (PsycINFO Database Record

Individuals in preclinical and clinical stages of Huntington's disease (HD) demonstrate impairments in olfactory functioning. In addition, HD patients are impaired in source memory for verbal stimuli. A task combining both source and odor memory may be particularly sensitive to early changes in HD. The present study examined source and item memory for olfactory and visual stimuli in 10 individuals with HD, 10 asymptomatic HD gene carriers, 8 nongene carriers who had a parent with HD, and 20 normal controls. During the study phase, a male and a female experimenter (sources) presented odors and objects to the participant in an alternating sequence. To assess item memory, a stimulus from the study phase (target) and a novel stimulus (distractor) were presented, and the participant was asked to choose the target. To assess source memory, the experimenter presented a stimulus and asked whether the male or female experimenter had previously presented the stimulus. Results indicate that source memory for both visual and olfactory stimuli was impaired in HD patients compared to normal controls. In asymptomatic gene carriers, however, source memory for olfactory stimuli, but not visual stimuli, was more impaired than in nongene carriers and normal controls. Furthermore, gene carriers and HD patients showed a similar degree of impairment in source memory for olfactory stimuli. The only significant impairment found in item memory was for olfactory stimuli in HD patients. These results suggest that source memory for olfactory stimuli may be particularly sensitive to neuropathological changes in preclinical stages of HD.

Five experiments were conducted to compare source memory to target memory. For the current purposes, source memory was defined as information that was learned from two sources (i.e. information input) whereas target memory was defined as information that was delivered to two sources (i.e. information output). The paradigm that we developed involved receiving concrete objects from two people in the source‐monitoring conditions or giving away these same objects to two people in the target‐monitoring conditions. This procedure allowed a direct comparison of source monitoring to target monitoring holding all other experimental variables constant. Target‐monitoring performance exceeded source monitoring except when the decision component of target monitoring was eliminated and incorporated into source monitoring. Commonalities and differences between source and target monitoring are discussed as are the real‐world implications of target memory for social behavior and facilitating communication. Copyright © 2002 John Wiley & Sons, Ltd.

The attention-elaboration hypothesis of memory for schematically unexpected information predicts better source memory for unexpected than expected sources. In three source-monitoring experiments, the authors tested the occurrence of an inconsistency effect in source memory. Participants were presented with items that were schematically either very expected or very unexpected for their source. Multinomial processing tree models were used to separate source memory, item memory, and guessing bias. Results show an inconsistency effect in source memory accompanied by a compensatory schema-consistent guessing bias when expectancy strength is high, that is, when items are very expected or very unexpected for their source.

GENERAL COMMENTARY article Front. Hum. Neurosci., 06 August 2012Sec. Cognitive Neuroscience Volume 6 - 2012 | https://doi.org/10.3389/fnhum.2012.00231

Adult age differences in external source monitoring were examined using three types of materials differing in degree of salience. Young (mean age = 25.2 years), young-old (mean age = 66.0 years), and old adults (mean age = 74.7 years) learned organizable words, objects, and subject-performed tasks, with a blocked or random presentation. Later, subjects were asked to recognize the items and to identify their origins. Results indicated an age-related deficit in both item memory and external source monitoring as reflected by lower recognition performance, and more source confusion errors with increasing age. A strong positive relationship between episodic item memory and source memory was found for all age groups. Overall, the results suggest that age deficits in source monitoring may be determined by the same factors as age deficits in item memory.

Recent basic science data indicate that in healthy individuals, self-referential processing and social cognition rely on common neural substrates. The authors assessed self-referential source memory and social cognition in a large sample of schizophrenia outpatients and healthy comparison subjects in order to compare how these critical processes are associated in the two groups. Ninety-one schizophrenia outpatients and 30 healthy comparison subjects were assessed on measures of basic social cognition and source memory for previously learned word items: self-generated, externally presented, and new words. Partial correlations and multiple regression analysis were used to test the association between social cognition measures and source memory performance and the contributions of source memory and general cognitive abilities to a social cognition composite score. Schizophrenia patients demonstrated significantly lower source memory for self-generated items (self-referential source memory) relative to comparison subjects but showed intact external source memory. In both groups, self-referential source memory and social cognition showed strong correlations. When the effects of general cognitive abilities were controlled for, these correlations were attenuated in the schizophrenia patients. Regression analysis revealed discrepancies between groups in the cognitive functions contributing to social cognition performance. Impaired self-referential source memory represents a unique cognitive deficit in schizophrenia. Moreover, the strong association between self-referential source memory and social cognition seen in healthy subjects is reduced in schizophrenia and is moderated by general cognitive abilities. Impairments in the neurocognitive system that underlies both self-referential and social cognition provide a parsimonious explanation for the disturbances in the sense of self and other that characterize schizophrenia.

Class stereotypes are simplistic generalizations about attributes, differences of the social class, and about roles of individuals and/or groups. Stereotypes provide perceives a basis to generate inferences about unseen orunobserved aspects of a stereotypic schema, enabling them to make conjectures beyond the information given. Multinomial Processing Tree Models(MPT) are theories about the decision processes that were involved in source monitoring and can provide separate parameters for source discrimination, item detection, and response biases. It has been suggested by stereotype studies in a framework of source monitoring that stereotypes provided after encoding and before test, might produce a response bias in favor of the stereotype. This bias can distort memory representations of earlier events, resulting in false memories. Previous studies suggested that participants may resort to guess based on their stereotypes knowledge in situations when they cannot remember the source in a source-monitoring task(Bayen, Nakamura, Dupuis, Yang, 2000). According to this guessing hypothesis, if stereotypes are activated during retrieval in an explicit way, participants are prone to consciously make use of stereotypes knowledge and to guess the source in a stereotype consistent manner, particularly when they fail to remember the actual source. However, recent research has provided mixed evidence. By controlling the guessing, other researchers still found that participants create illusory recollections when stereotypes are activated during retrieval in an explicit way(Dodson, Darragh, Williams, 2008). So an intriguing question is: If guessing plays a critical role in creating false memories, what other factors should be responsible for false memories after controlling guessing? In this study, MPT were used for the measurement of cognitive processes in two source monitoring experiments. Sixty-six college students of normal vision, twenty-six in Experiment 1 and forty in Experiment 2, were enrolled to participate. The purpose of Experiment 1 was to determine how stereotypes influence source-monitoring decision processes when the class stereotypes are subliminally primed during retrieval. The results showed that when the subliminally primed class stereotype is provided during retrieval, participants' memory performance was distorted in a stereotype consistent manner, presumably through guessing responses. Particularly, the automatically activated class stereotypes affect source guessing process, thus producing false memories. In Experiment 2, explicit warning was provided to reduce false memory. We aimed to investigate how stereotypes influence decision processes of source monitoring, when the class stereotypes are explicitly primed during retrieval. Our results demonstrated that participants showed similar stereotype-induced false memories even after the stereotypes guessing at conscious level was controlled. Although it was difficult to fully control the stereotypes guessing at unconscious level, the explicit warning could lower the rate of false recall. Thus, the unconscious stereotypes guessing and illusory recollections might be the basis for false memories in a stereotype consistent manner. To sum up, the present study indicated that class stereotypes can affect source memory under different conditions in a flexible way. The activation of class stereotypes, in a source monitoring framework, affects not only guessing processes but also illusory recollections, both of which provide a potential basis for erroneous source attributions.

Introduction Remembering relationships between items (information) and the contexts (sources) in which they are framed is crucial for everyday functioning. Total sleep deprivation (TSD) impairs this ability, with evidence suggesting that TSD affects source memory even when items are remembered. Source memory deficits imply problems with associative memory, which relies on hippocampal functioning, known to be altered by TSD. Serotonin is highly expressed in the hippocampus, is influenced by TSD, and may be part of a mechanism by which TSD degrades source memory. We investigated the association between 5-HTTLPR, a functional length polymorphism of the human serotonin transporter gene (SLC6A4), and item and source memory during TSD. Methods N=34 healthy adults (ages 27.3±4.9y; 18 female) participated in a 4-day/3-night laboratory TSD study. Participants underwent 38h TSD, preceded and followed by 10h sleep opportunities. At baseline and 24h later during TSD, they completed an item/source memory task. Participants listened to a list of 60 words each presented by a male or female speaker (study phase). They were then tested for recognition of the words (items) out of 60 old and 60 new words presented visually, and were asked to identify the corresponding speakers (sources, male or female). Results The genotype distribution was in Hardy-Weinberg equilibrium (P=0.34), with 35.3% long/long, 41.2% long/short, 23.5% short/short. Mixed-effects ANOVA showed a significant adverse effect of TSD for both item recognition (P< 0.001) and source recognition (P< 0.001), where TSD degraded source memory even when item recognition was accurate. There were no 5-HTTLPR genotype effects on item memory. However, there was a significant main effect for genotype on source memory (P=0.019), and a genotype by TSD interaction (P=0.018). For accurately recognized items, source memory was largely preserved for the short/short genotype but impaired for carriers of the long allele, and especially the long/long genotype. Conclusion 5-HTTLPR genotype predicted source memory deficits from TSD, distinct from item memory deficits unaffected by genotype, which confirms that item and source memory deficits due to TSD are dissociable. Furthermore, TSD’s impact on binding of items and sources in memory may be mediated by hippocampal serotonin. Support (if any) NIH R21CA167691, WSU Anthony Marchionne and Foundry10 Bridge fellowships

The present study examined the role of enactment in source memory in a cognitively impaired population. As seen in healthy older adults, it was predicted that source memory in people with mild cognitive impairment due to Alzheimer's disease (MCI-AD) would benefit from the self-reference aspect of enactment. Seventeen participants with MCI-AD and 18 controls worked in small groups to pack a picnic basket and suitcase and were later tested for their source memory for each item. For item memory, self-referencing improved corrected recognition scores for both MCI-AD and control participants. The MCI-AD group did not demonstrate the same benefit as controls in correct source memory for self-related items. However, those with MCI-AD were relatively less likely to misattribute new items to the self and more likely to misattribute new items to others when committing errors, compared with controls. The enactment effect and self-referencing did not enhance accurate source memory more than other referencing for patients with MCI-AD. However, people with MCI-AD benefited in item memory and source memory, being less likely to falsely claim new items as their own, indicating some self-reference benefit occurs for people with MCI-AD.

A functional gradient has been proposed across the medial temporal lobes (MTL) such that the anterior MTL is thought to support processing of individual items (e.g., item memory and complex object perception), whereas the posterior MTL is thought to support item-context retrieval (e.g., source memory). Whereas functional imaging studies have provided evidence supporting this anatomical organization, results from structural analyses remain inconclusive. The current study examined the relationship between volume of MTL regions of interest (ROIs), and performance on a source memory task and a fine-grain complex object perception task, in healthy young adults (mean age = 21.5, range = 18-29). Using a semiautomated procedure, we segmented the parahippocampal and perirhinal cortices (PHC, PRC), posteromedial and anterolateral entorhinal cortices (pmERC, alERC), and posterior and anterior hippocampus (postHC, antHC) on high-resolution T2-weighted MRIs. Regional volumes were computed as proportions of intracranial volume, and as posterior-anterior volumetric ratios (PHC:PRC, pmERC:alERC, postHC:antHC). Partial-least squares regressions were applied to predict source and item memory, and perceptual discrimination accuracy, based on ROI and ratio volumes. In our ROI regressions, we found that postHC volume was positively correlated with a latent factor predicting source memory, and PRC and antHC volumes were negatively correlated to this latent factor. In our ratio regressions, we observed an effect relating the posterior-anterior distribution of gray matter across the MTL with source memory. Our results demonstrate differential associations between anterior and posterior MTL and source memory performance. Findings from this study highlight the importance of considering patterns of structure-behavior associations in the neurobiology of episodic memory.

Negative emotion elicited in high school students enhances consolidation of item memory, but not source memory.

Females’ superiority in item memory, but not source memory for neutral and emotional Chinese words

Affective states are closely linked to attention to internal aspects of the self (i.e., self-focused attention). We investigated how self-focused attention induced by emotional experiences affects memory for subsequently presented information. Prior to incidental encoding of affectively neutral target words, participants were induced to feel shame or anger through autobiographical recall (vs. no emotion-induction control condition). Memory for words (item memory) and their associated contextual features (source memory) were subsequently assessed. Self-focused attention, measured by the private self-consciousness scale, was highest in the shame condition, followed by the anger and then control conditions. Item memory was significantly impaired in the shame condition compared to both the anger and control conditions, and self-focused attention negatively mediated the effect of emotion condition on memory performance. Source memory did not significantly differ across the emotion conditions, and we discuss possible factors contributing to this null finding. Our findings suggest that emotion-induced self-focused attention may reduce attentional resources available for encoding task-relevant external information.

The authors analyzed source memory performance with an unequal-variance signal detection theory model and compared the findings with extant threshold (multinomial and dual-process) models. In 3 experiments, receiver operating characteristic (ROC) analyses of source discrimination revealed curvilinear functions, supporting the relative superiority of a continuous signal detection model when compared with a threshold model. This result has implications for both multinomial and dual-process models, both of which assume linear ROCs in their description of source memory performance.