How social interactions affect emotional memory accuracy: Evidence from collaborative retrieval and social contagion paradigms.

In daily life, emotional events are often discussed with others. The influence of these social interactions on the veracity of emotional memories has rarely been investigated. The authors (Choi, Kensinger, & Rajaram Memory and Cognition, 41, 403-415, 2013) previously demonstrated that when the categorical relatedness of information is controlled, emotional items are more accurately remembered than neutral items. The present study examined whether emotion would continue to improve the accuracy of memory when individuals discussed the emotional and neutral events with others. Two different paradigms involving social influences were used to investigate this question and compare evidence. In both paradigms, participants studied stimuli that were grouped into conceptual categories of positive (e.g., celebration), negative (e.g., funeral), or neutral (e.g., astronomy) valence. After a 48-hour delay, recognition memory was tested for studied items and categorically related lures. In the first paradigm, recognition accuracy was compared when memory was tested individually or in a collaborative triad. In the second paradigm, recognition accuracy was compared when a prior retrieval session had occurred individually or with a confederate who supplied categorically related lures. In both of these paradigms, emotional stimuli were remembered more accurately than were neutral stimuli, and this pattern was preserved when social interaction occurred. In fact, in the first paradigm, there was a trend for collaboration to increase the beneficial effect of emotion on memory accuracy, and in the second paradigm, emotional lures were significantly less susceptible to the "social contagion" effect. Together, these results demonstrate that emotional memories can be more accurate than nonemotional ones even when events are discussed with others (Experiment 1) and even when that discussion introduces misinformation (Experiment 2).

Older adults can suppress unwanted memories when given an appropriate strategy.

Memory suppression refers to the ability to exclude distracting memories from conscious awareness, and this ability can be assessed with the think/no-think paradigm. Recent research with older adults has provided evidence suggesting both intact and deficient memory suppression. The present studies seek to understand the conditions contributing to older adults' ability to suppress memories voluntarily. We report 2 experiments indicating that the specificity of the think/no-think task instructions contributes to older adults' suppression success: When older adults receive open-ended instructions that require them to develop a retrieval suppression strategy on their own, they show diminished memory suppression compared with younger adults. Conversely, when older adults receive focused instructions directing them to a strategy thought to better isolate inhibitory control, they show suppression-induced forgetting similar to that exhibited by younger adults. Younger adults demonstrate memory suppression regardless of the specificity of the instructions given, suggesting that the ability to select a successful suppression strategy spontaneously may be compromised in older adults. If so, this deficit may be associated with diminished control over unwanted memories in naturalistic settings if impeded strategy development reduces the successful deployment of inhibitory control.

The route to an integrative associative memory is influenced by emotion.

Though the hippocampus typically has been implicated in processes related to associative binding, special types of associations--such as those created by integrative mental imagery--may be supported by processes implemented in other medial temporal-lobe or sensory processing regions. Here, we investigated what neural mechanisms underlie the formation and subsequent retrieval of integrated mental images, and whether those mechanisms differ based on the emotionality of the integration (i.e., whether it contains an emotional item or not). Participants viewed pairs of words while undergoing a functional MRI scan. They were instructed to imagine the two items separately from one another ("non-integrative" study) or as a single, integrated mental image ("integrative" study). They provided ratings of how successful they were at generating vivid images that fit the instructions. They were then given a surprise associative recognition test, also while undergoing an fMRI scan. The cuneus showed parametric correspondence to increasing imagery success selectively during encoding and retrieval of emotional integrations, while the parahippocampal gyri and prefrontal cortices showed parametric correspondence during the encoding and retrieval of non-emotional integrations. Connectivity analysis revealed that selectively during negative integration, left amygdala activity was negatively correlated with frontal and hippocampal activity. These data indicate that individuals utilize two different neural routes for forming and retrieving integrations depending on their emotional content, and they suggest a potentially disruptive role for the amygdala on frontal and medial-temporal regions during negative integration.

Age-related changes in associative memory for emotional and nonemotional integrative representations.

Events often include novel combinations of items. Sometimes, through the process of integration, we experience and remember these items as parts of a whole rather than as separate entities. Recent research with younger adults has demonstrated that successfully integrating 2 nonemotional items at encoding, instead of imagining them separately, produces a disproportionately larger associative memory benefit than integrating an emotional and a nonemotional item. In the first study to examine whether age and emotion interact to influence integration, we used 2 measures of integrative success-the ability to successfully retrieve integrations, measured through associative cued recall, and the ability to successfully generate integrated representations at encoding, measured through self report. The cued-recall results (Experiments 1 and 2) revealed that the emotional content of the word pairs interacts to influence the effect of integration on older adults' associative memory, but in the opposite direction of younger adults: Older adults showed no associative retrieval benefit of integration over nonintegration for nonemotional pairs, but they showed a significant integrative benefit for emotional pairs. We also demonstrated (Experiment 2) that encoding time interacts with emotion and integration in different ways for older and younger adults: Putting younger adults under time pressure reduced their success in generating integrated representations at encoding for nonemotional pairs, whereas for older adults it disrupted their ability to generate integrated representations for emotional pairs. We discuss possible age-related differences in the processes used to create emotional and nonemotional integrations.

Oversimplification in the study of emotional memory.

This Short Review critically evaluates three hypotheses about the effects of emotion on memory: First, emotion usually enhances memory. Second, when emotion does not enhance memory, this can be understood by the magnitude of physiological arousal elicited, with arousal benefiting memory to a point but then having a detrimental influence. Third, when emotion facilitates the processing of information, this also facilitates the retention of that same information. For each of these hypotheses, we summarize the evidence consistent with it, present counter-evidence suggesting boundary conditions for the effect, and discuss the implications for future research.

A review of the neural and behavioral consequences for unitizing emotional and neutral information.

A special type of association, called a "unitization," is formed when pieces of information are encoded as a single representation in memory (e.g., "shirt" and "blue" are encoded as a "blue shirt"; Graf and Schacter, 1989) and typically are later reactivated in memory as a single unit, allowing access to the features of multiple related stimuli at once (Bader et al., 2010; Diana et al., 2011). This review examines the neural processes supporting memory for unitizations and how the emotional content of the material may influence unitization. Although associative binding is typically reliant on hippocampal processes and supported by recollection, the first part of this review will present evidence to suggest that when two items are unitized into a single representation, memory for those bound items may be accomplished on the basis of familiarity and without reliance on the hippocampus. The second part of this review discusses how emotion may affect the processes that give rise to unitizations. Emotional information typically receives a mnemonic benefit over neutral information, but the literature is mixed on whether the presence of emotional information impedes or enhances the associative binding of neutral information (reviewed by Mather, 2007). It has been suggested that the way the emotional and neutral details are related together may be critical to whether the neutral details are enhanced or impeded (Mather, 2007; Mather and Sutherland, 2011). We focus on whether emotional arousal aids or inhibits the creation of a unitized representation, presenting preliminary data, and future directions to test empirically the effects of forming and retrieving emotional and neutral unitizations.

The effects of emotion and encoding strategy on associative memory.

Research has demonstrated that when discrete pieces of information are integrated together at encoding--imagining two items together as a single entity, for example--there is a mnemonic benefit for their relationship. A separate body of literature has indicated that the presence of emotional information can have an impact on the binding of associated neutral details, in some cases facilitating associative binding (MacKay et al. Memory and cognition 32:474-488, 2004; Mather, perspectives on psychological science 2:33-52, 2007), and in other cases impeding the processing of associated details (Easterbrook, Psychological Review 66:183-201, 1959; Kensinger, Emotion review 1:99-113, 2009). In the present experiments, we investigated how memory for neutral words is affected by the emotionality of the information with which they are presented (whether with an emotional word or a second neutral word) and the encoding context (integrated or nonintegrated strategy). Participants viewed word pairs and were instructed to visualize the items as an integrated unit or to visualize them separately from one another. The results of Experiment 1 showed a disproportionate mnemonic benefit for neutral items that were integrated with other neutral items over those integrated with emotional items. The results of Experiments 2A and 2B showed that this effect interacted with encoding time: When given 2 s to encode, participants showed no effect of integration on memory for neutral-neutral pairs, but showed a significant mnemonic benefit for integrating emotional-neutral pairs. When given 4 or 6 s, the integrative benefit increased significantly for neutral-neutral pairs but decreased for emotional-neutral pairs. These results suggest that creating an integrated mental image of two neutral items requires a more time-consuming process than integrating an emotional and a neutral item, but that extra effort may result in a downstream mnemonic benefit.

Effects of emotion and age on performance during a think/no-think memory task.

Recent studies have demonstrated that young adults can voluntarily suppress information from memory when directed to. After learning novel word pairings to criterion, participants are shown individual words and instructed either to "think" about the associated word, or to put it out of mind entirely ("no-think"). When given a surprise cued recall test, participants typically show impaired recall for no-think words relative to think or "control" (un-manipulated) words. The present study investigated whether this controlled suppression effect persists in an aged population, and examined how the emotionality of the to-be-suppressed word affects suppression ability. Data from four experiments using the think/no-think task demonstrate that older and younger adults can suppress information when directed to (Experiment 1), and the age groups do not differ significantly in this ability. Experiments 2 through 4 demonstrate that both age groups can suppress words that are emotional (positive or negative valence) or neutral. The suppression effect also persists even if participants are tested using independent probe words that are semantically related to the target words but were not the studied cue words (Experiments 3 and 4). These data suggest that the cognitive functioning necessary to suppress information from memory is present in older adulthood, and that both emotional and neutral information can be successfully suppressed from memory.