Emotion, Mood, and Memory
EMOTION, MOOD, AND MEMORY
The ways in which we attend, learn, and remember are related to our transitory moods and to our enduring emotional states. Intuitively appealing to the self-reflective person, this claim has been verified by experimental and clinical psychologists in both laboratory and naturalistic studies. In some studies, psychologists measure differences in emotional states and determine whether those differences are associated with differences in the ways that the participants perform cognitive tasks. These studies usually focus on unpleasant emotions and moods, such as depression and anxiety. In other studies, psychologists attempt to induce either unpleasant or pleasant moods in the participants (perhaps by having them listen to different types of music) and then examine how performance is affected by these manipulations. Both types of research have tried to answer two major questions about the interaction of mood and memory: Do people remember events that are emotionally consistent with their moods better than other events? Do depressed and anxious moods hinder performance on neutral cognitive tasks?
People remember episodes and materials that are consistent with their moods more often than they remember other occurrences; this phenomenon is known as mood-congruent memory (MCM). MCM can sometimes be attributed to the ways that people initially interpret the events to be remembered because interpretations tend to be mood-congruent. A clear example of mood-congruent interpretation can be seen in research conducted by Michael Eysenck and his colleagues (1987): Anxious participants, more often than nonanxious participants, spelled spoken homophones (such as die and dye) to coincide with the more threatening concept. Andrew Mathews and his associates (1989) found similar mood-congruent interpretation on a test of implicit memory. In this test, the participants were shown the first three letters of words and were asked to complete them to form the first word that came to mind. The anxious subjects completed with threat-related words that they had seen in an earlier task more often than other types of previously seen and unseen words; nonanxious subjects did not show this bias. As they occur in both initial encounters and later indirect tests of memory, these biased interpretations occur automatically or without any intent to focus on mood related meaning.
On more direct tests of memory, such as tests of explicit recall, anxious people do not always remember anxiety-related material better than other material, perhaps because they turn their attention away from anxiety-provoking stimuli, once they are conceived. Research concerned with depressed and sad states, however, shows more consistent evidence of MCM for both autobiographical and experimentally controlled events. A thorough review of MCM is provided in Cognitive Psychology and Emotional Disorders (Williams, Watts, MacLeod, and Mathews, 1997), which also describes variations and exceptions to the basic findings. One variation is that depressed moods are often associated with a reduction in the recall of positively toned events instead of an increase in the recall of negative events. More exceptional is the finding that temporarily sad students have shown evidence of mood-incongruent recall (better recall for positive material), which Parrott and Sabini (1990) have interpreted as an outcome of the students' elaborative processing of positive material, in attempt to improve their moods.
To the extent that MCM is observed in depression, it reflects enduring concerns with negative events and at the same time plays an important role in maintaining depressed mood. Sonja Lyubormirsky and her colleagues (1998) found that ruminations by students in depressed moods increased their recall of negative events. Moreover, just as they tend to remember fewer positive episodes from the past, depressed people also tend to expect fewer positive events to occur in the future (MacLeod, 1999).
Mood-Related Impairments in Memory for Emotionally Neutral Events
Because depressed and anxious people ruminate about self concerns, it not hard to imagine that they devote less attention to the emotionally neutral events of everyday experience. Some routine cognitive acts require little attention for successful performance; the cognitive processes involved are relatively automatic, which means that they are well practiced and can occur simultaneously with other cognitive processes, even rumination about personal concerns. Other tasks require a more laborious and deliberate focus of attention if good performance is to be achieved. In short, cognitive tasks vary in the degree to which focused attention is required for good performance. This is true of procedures that are performed during initial exposure or learning and tasks that are devised to reveal memory for past events.
At the time of initial learning, for example, reading a long list of unrelated words requires little effort by fluent readers, but organizing them in ways that will be useful during later attempts to remember them clearly requires more deliberate focus. Similarly, tests of memory for those words vary in the degree of focused attention that they require. Rereading the same words is one index of memory (in that the previously read words can be read faster than new words). This type of implicit-memory test involves procedures that are relatively automatic. In contrast, trying to recall the words on the list is a deliberate task that can benefit from a great deal of attention and the use of special strategies.
The learning and memory tasks that benefit from focused attention are the tasks that present difficulties to depressed and anxious people; they perform less well than do people who are not mood-impaired. Weingartner and his colleagues (1981), for example, discovered that clinically depressed patients could learn lists of words organized into simple categories as well as could other people, but when the same word lists were disorganized, the depressed patients learned less well. When people approach these types of learning tasks by providing their own organization or by using other elaborative strategies, they later enjoy benefits on tests of deliberate memory. In contrast, depressed people use fewer self-initiated procedures and suffer the memory-related consequences.
Similar conclusions can be reached in examining different types of memory tests. Hertel and Hardin (1990), for example, found that depressed college students performed as well as other students when the test of memory did not explicitly focus attention on the past event (i.e., the spelling of homophones that indirectly revealed memory for their prior exposure). When the test required such explicit focus, however, depressed students did not spontaneously use strategies for recognition that characterized the performance of the other students. Similarly, in tests of autobiographical memory, depressed patients' recall is often inappropriately general. They respond to instructions to recall prior specific events when given cues (e.g., happy) by citing categories of events instead of particular episodes (e.g., going to baseball games, instead of the time my dad took me to see the Yankees for my birthday ; Healy and Williams, 1999).
Why do mood-impaired people experience impaired attention and corresponding memory deficits? Some researchers (e.g., Weingartner et al., 1981) have proposed that the deficits result from a fundamental depletion of resources, possibly associated with biochemical changes. Alternatively or in addition, the difficulties might indirectly reflect mood-impaired people's enduring and ruminative concern with mood-related aspects of their experience—aspects that are often irrelevant to the task at hand. These task-irrelevant thoughts can distract attention when participants are left to their own devices (e.g., when they are told to learn a list of words). Yet when learning or memory tasks are devised in ways that constrain attention to task materials, specify appropriate strategies, or distract from personal concerns, mood-impaired people may perform as well as others (Hertel, 2000).
Memory for emotionally neutral events might also benefit from the correspondence of mood at the time of the test to the mood at the time of initial learning. The advantage of a similar mood state on both occasions has been called mood-dependent memory (MDM) and is similar to other state-dependent memory effects, such as those obtained with alcohol. MDM also has much in common with MCM: Remembering mood-congruent events is often a matter of being in the same mood at the test as when those events were encountered previously. However, MDM is properly demonstrated with emotionally neutral materials to be learned and recalled. When the materials are not inherently related to mood—when MCM is not involved—attempts to demonstrate MDM often do not succeed. A consistent emotional state by itself is not a strong basis for retrieving memories, particularly when other more obvious cues are available. However, Eric Eich (1995) provides evidence that MDM is a robust phenomenon when, like mood, the events to be remembered and the cues for retrieving them arise from the individual rememberer, instead of being provided by others.
In conclusion, the most inclusive framework for describing mood, emotion, and memory is one that emphasizes the nature and content of ongoing thoughts. In all but the most transitory mood states, the extent to which people think about their personal concerns is also the extent to which they remember emotionally consistent experiences and fail to remember experiences unrelated to their mood states.
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