تاثیر اضطراب خصلتی بر قضاوت های فراوانی و یاداوری

Individuals high in trait anxiety believe that they are more at risk for a variety of threatening events. Subjective probability estimates of risk presumably rely on frequency-of-occurrence information in memory. This study sought to compare individuals differing in the trait of anxiety on frequency estimates and recall. Neutral and threatening words were presented varying numbers of times. An interaction between trait anxiety and word type indicated that individuals with high trait anxiety estimated greater frequencies for threatening words than did individuals with low trait anxiety. There were no differences between the groups in subsequent recall. Higher false recognitions of threatening words by high trait anxious participants suggested the use of a different decision strategy or greater activation and covert rehearsal of threat.

“How likely is it that you will be assaulted?” To answer this question, an individual may rely on several sources of information in memory. These sources may include personal experiences as a victim, accounts from friends or relatives victimized by assault, or graphic episodes reported by the news media. The individual might even recall several times that he or she imagined being assaulted. All of these memories concern frequency-of-occurrence information, or a count of how often something has occurred. Frequency-of-occurrence information in memory is used to judge the likelihood of a future event (Hasher & Zacks, 1984). Individual differences in the personality trait of anxiety have been found to bias subjective judgments of risk. High trait anxious individuals are particularly prone to believing that they are at risk for certain negative or harmful events (Butler and Mathews, 1987 and Gasper and Clore, 1998). Although the literature shows that high trait anxious individuals overestimate risk, we do not know how they monitor the actual frequency of threatening information in the environment. The purpose of this study was to examine how individuals differing in the trait of anxiety monitor the frequency-of-occurrence of presented threatening and neutral word stimuli. Differences in the ability to monitor actual frequency might explain at least some of the judgment biases seen in high trait anxious individuals. Several studies have shown that trait anxiety influences interpretations of uncertainty or ambiguity. High trait anxious individuals are more likely than low trait anxious individuals to write down the spelling with the more threatening meaning when presented auditorily with homophones having both threatening (e.g., die) and nonthreatening (e.g., dye) meanings (Byrne and Eysenck, 1993, Dalgleish, 1994 and Eysenck et al., 1987). Similarly, when presented with sentences having ambiguous meanings (e.g., “The doctor examined little Emily’s growth.”), high trait anxious individuals are more likely than low trait anxious individuals to interpret the sentences with a threatening meaning (MacLeod & Cohen, 1993). Only two studies have examined the relative contributions of state and trait anxiety to judgments of frequency or probability. Butler and Mathews (1987) compared risk estimates of a group of students anticipating an exam having important consequences with a similar group of students who were not expecting an exam. High trait anxiety was associated with higher perceived risk to oneself for a variety of negative events related to and unrelated to the exam. State anxiety was also associated with increased risk estimates, but related to the exam only. In a similar study, Gasper and Clore (1998, Experiment 1) compared risk estimates of students anticipating an exam and found that individuals with high trait anxiety estimated higher probabilities than individuals with low trait anxiety for a variety of personal and impersonal risks. In addition, they showed that individuals with high trait anxiety relied more on their increased state anxiety as information in making probability judgments. Thus it appears that increases in an anxious mood state may increase the subjective probabilities of risk associated with the perceived cause of the increased anxiety (Butler & Mathews, 1987); or may be a source of information used by individuals when making judgments of risk (Gasper & Clore, 1998). But despite changes in state anxiety, trait anxiety is associated with a pervasive tendency to believe that the probability of risk or harm is greater. Butler and Mathews (1987) propose two possible cognitive mechanisms for the judgment and interpretive biases seen in high trait anxiety: the use of judgmental heuristics and the influences of existing schemata in memory. When people make judgments about the likelihood of certain events they may rely on an availability heuristic, that is, the ease with which past occurrences of similar events can be accessed from memory (Tversky and Kahneman, 1973 and Tversky and Kahneman, 1974). The ease with which past occurrences can be accessed is in turn thought to be a function of the extent or elaboration of activated threat-related schemata in memory. Butler and Mathews suggest that the threat-related schemata are more extensive and elaborated in individuals with high trait anxiety compared to individuals with low trait anxiety. Activated threat-related schemata could have the effect of increasing the availability of threat-related information in memory, raising the sensitivity to anxiety related cues in the environment, and increasing the tendency to label or categorize input as threatening — all of which could lead to an overestimation of subjective personal risk. The schema-based theories set forth the view that subjective probability estimates involve cognitive processes that take place both at retrieval and at encoding. MacLeod and Campbell (1992) reported several studies suggesting that when asked to judge the probability of future events, people rely on retrieval of individual instances of similar events. Other studies have shown estimates of frequency to be largely independent of recall. Watkins and LeCompte (1991) reported several experiments comparing the relative deviations of recall and frequency estimation from true category frequencies and found that recall was not sufficiently informative to account for frequency estimates. Manis, Shedler, Jonides and Nelson (1993) reported studies showing that performance on a frequency-of-occurrence estimation task was predicted by true frequency-of-occurrence and not by the recall of specific instances. According to Hasher and Zacks, 1979 and Hasher and Zacks, 1984) encoding of frequency is an automatic cognitive process that takes place without intention or effort and is independent of the more effortful or strategic cognitive processes. They presented evidence suggesting that a variety of individual differences such as age, ability, stress, and arousal that traditionally affect tests of effortful cognitive processing (e.g., recall) have no effect on memory for frequency. Although many studies have questioned automatic encoding of frequency (e.g., Birnbaum et al., 1987 and Fisk, 1986), it has often been difficult to rule out other explanations. Strong support for the view that frequency is monitored automatically is gained from a recent study of Alzheimer’s patients showing that frequency judgments can remain quite accurate even when recall is severely impaired (Wiggs, Martin & Sunderland, 1997). Because mood congruent memories appear to be more available for various judgments and interpretations, many researchers have attempted to document a preferential bias to recall threat-related information in anxiety on explicit memory tasks. Studies examining mood-congruent memory in anxiety typically have participants study lists consisting of both anxiety-related and nonanxiety-related words. Participants are then tested on the recall of those words. An explicit memory bias for anxiety-related words in high trait anxious individuals was reported by Reidy and Richards (1997), however upon further analysis the researchers determined that the effect was due to state anxiety differences. Other studies looking for an explicit memory bias for threat words in trait anxiety have found none (Mathews et al., 1989 and Richards and French, 1991), even when high trait anxious individuals have shown a processing (interpretive) bias for the same words in a previous task (Dalgleish, 1994). Several current theories suggest that anxiety may affect both automatic and strategic cognitive processes (e.g., Beck and Clark, 1997, Mathews and MacLeod, 1994 and Williams et al., 1988). These theories can account for both the interpretive biases and the lack of memory bias in high trait anxiety. Automatic processing of threat cues may predominate in attentional and interpretive tasks whereas strategic processing (intentional avoidance of elaboration) may predominate in recall tasks. Because frequency-of-occurrence judgments rely (at least to some extent) on automatic cognitive processes and because frequency information in memory may play an important role in subjective judgments and beliefs (Hasher & Zacks, 1984), a simple frequency monitoring study was undertaken to look at the effects of trait anxiety on memory for frequency-of-occurrence and recall. In this word frequency estimation paradigm, college students were presented with a series of physically threatening and neutral words. The words were shown either two, five, or eight times at a fairly rapid rate. Following the presentation of words, the participants were asked to estimate the number of times they saw each word. Some of the words on the frequency test were words that did not appear on the study list, and those words served as distractors. It was predicted that high trait anxious participants would estimate relatively greater frequencies for threatening words than would low trait anxious participants. It was also predicted that there would be no differences between groups on recall.