اثر گرایش اجتنابی بر شدت خاطرات مزاحم در یک نمونه جامعه از دانشجویان

Abstract The purpose of the study was to examine the factors that influence the enhancement of intrusive memories, with a particular focus on individuals’ avoidant tendencies: thought suppression, rumination, and dissociation. A total of 641 undergraduates (253 men and 388 women, M = 20.0 years) completed a battery of measures: (1) a questionnaire about intrusive memories (contents and degree of intrusion measured by the Impact of Event Scale); (2) the Beck Depression Inventory-II; (3) the White Bear Suppression Inventory; (4) the Negative Rumination Trait Scale; and (5) the Dissociative Experiences Scale. Approximately, 55% of the participants had experienced intrusive memories, of which over 90% had negative implications. The individual’s avoidant tendencies, especially thought suppression, had significant influence on the degree of intrusion of negative memories, once participants’ depressive symptoms were controlled. Clinical and research implications of the study were outlined.

. Introduction Intrusive memories have been identified as a part of the symptoms of posttraumatic stress disorders (PTSD) (American Psychiatric Association, 2000). Whereas ordinary autobiographical memories are under conscious control, intrusive memories appear to be entirely spontaneous and relatively uncontrollable, characterized by intense affect and strong sensory elements (Brewin, Dalgleish, & Joseph, 1996). A number of studies clearly suggest that a high level of intrusion of traumatic memories is a risk factor for later psychopathology. For example, intrusive re-experiencing that persists for several months has been shown to predict long-term PTSD symptoms (McFarlane, 1992). Although DSM-IV-TR (American Psychiatric Association, 2000) lists intrusive symptoms exclusively as a feature of PTSD and Acute Stress Disorder, previous studies have suggested that patients with depression also experience intrusive memories at a level equivalent to that of patients with PTSD (e.g., Reynolds & Brewin, 1999). Moreover, Brewin, Christodoulides, and Hutchinson (1996) included a non-clinical population in their surveyed subjects, indicating that intrusive memories are a more common phenomenon than has hitherto been supposed in this population. The studies with an empirical approach have clarified which individual psychological properties enhance and maintain intrusive memories. First of all, depressive symptoms seem to be considered a critical factor that affects the occurrence of intrusive memories. Comorbidity surveys showed that about half the people with a lifetime history of PTSD also had a lifetime history of major depression (Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995). Moreover, it was found that prior depression increased the likelihood of PTSD (Acierno, Resnick, Kilpatrick, Saunders, & Best, 1999). With regard to this relationship, it was indicated that depression leads to an increase in the accessibility of specific autobiographical memories (Brewin et al., 1998 and Reynolds and Brewin, 1999). The relationship may be due to the effect of mood-congruence: a recent study based on an experimental method clarified that depressed mood is associated with unpleasant intrusive memories (Bywaters, Andrade, & Turpin, 2004). Cognitive theories of PTSD have indicated that avoidant strategies related to traumatic memories are generally considered to be a central factor in enhancing and maintaining PTSD symptoms (e.g., Brewin and Holmes, 2003 and Steil and Ehlers, 2000). According to these theories, avoidant tendencies generally seem to prevent adequate emotional processing of traumatic experiences, thereby interfering with the integration and restructuring of dysfunctional cognitions concerning the trauma. It is known that PTSD patients demonstrate a wide range of avoidant tendencies. For example, patients with PTSD seem to engage in thought suppression to avoid or end particular thoughts, images, or memories whenever trauma memories intrude into their consciousness ( Brewin & Holmes, 2003). Thought suppression refers to the conscious attempt to avoid certain thoughts; it seems to be a counter-productive defense strategy that produces more rather than fewer thoughts about the topic intended to be suppressed ( Wegner, Schneider, Carter, & White, 1987). In addition, rumination is thought to be another form of avoidance practiced by patients with PTSD ( Steil & Ehlers, 2000). Rumination appears to focus on experiences surrounding the traumatic event rather than the event itself, thereby interfering with the formation of more complete trauma memories. It is postulated that rumination blocks the emotional processing of distressing experiences, while concurrently connecting these experiences to many other stimuli, thereby enhancing their accessibility in memory networks ( Ehlers & Clark, 2000). Lastly, dissociation is also considered to be an avoidant psychological process. Dissociation is thought to provide an escape mechanism from one’s awareness of distressing and confusing emotional states by compartmentalizing information and affect ( Putnam, 1993). While temporal dissociation seems adaptive to stressful incidents ( Ludwig, 1983), chronic use of dissociation appears to prevent the adequate encoding of traumatic memories and the integration of them into ordinal autobiographical ones, leading to the enhancement of intrusive memories ( Ehlers and Clark, 2000 and Van der Kolk and Fisler, 1995). The purpose of the study was to examine the factors that influence the enhancement of intrusive memories, with a particular focus on individuals’ avoidant tendencies. Although previous studies of PTSD have indicated that emotional instability, such as that implied by depressive symptoms, is closely related to PTSD symptoms, an individual’s avoidant tendencies such as thought suppression, rumination, and dissociation would also be hypothesized to make an additional contribution to the intensity of intrusive memories above and beyond the depressive symptoms themselves. The study further explored the relative impacts of thought suppression, rumination, and dissociation on intrusive memories.

4. Results 4.1. The contents and frequencies of intrusive memories After a screening of the contents of the reported memories, 48 participants were precluded because their contents could not be identified as specific kinds of memories (e.g., dream, fantasy, or thought). Consequently, 326 (55.0%) out of the total 593 participants were considered to have reported intrusive memories. Then their memories were categorized using the Affinity Diagram (Kawakita, 1967), which organizes large amounts of data (opinions, ideas, etc.) into groupings based on their relationships. The frequencies and their proportions to the total number of participants were the following: “interpersonal quarrels” (n = 58; 9.8%) (e.g., quarrels with friends, family, and teachers); “psychological and physical assaults” (n = 39; 6.6%) (e.g., sexual and physical assault, bullying, and betrayal); “positive events” (n = 31; 5.2%) (e.g., winning awards/competitions and warm communications with family or friends); “serious injuries” (n = 29; 4.9%) (e.g., injuries in traffic accidents and bone fractures); “embarrassing experiences in front of others” (n = 26; 4.4%); “deaths of family and friends” (n = 18; 3.0%); and “other negative events” (n = 75; 12.6%) (e.g., failures in exams and defeats in games). Moreover, 8.4% (n = 50) of the participants refused to write down the contents of their intrusive memories, noting that “I do not want to write the content” or “I am afraid to recollect the content,” suggesting that the refused contents implied negative connotations. As a result, the participants who reported intrusive memories with negative implications amounted to about 50% of the total participants and over 90% of the participants with intrusive memories. 4.2. The effects of avoidant tendencies on the degree of negative intrusive memories The present study focused on the avoidance of intrusive memories with negative implications. The participants who reported intrusive memories with positive implications were excluded from the study, because the mechanism that enhances the intrusion of positive memories was thought to be different from the one that facilitates negative memories. Moreover, the participants who failed to answer any item of any measure were also excluded. Consequently, 282 participants out of the 325 who admitted to intrusive memories were included in the following analyses. The means, standard deviations, and correlation matrix of the variables of interest are shown below. These reflect the IESint, the BDI-II, the WBSIsup, the NRTS, and the DES, as well as the demographic variables of age and gender (Table 1). The variable of gender was dummy-coded 1 for men and 2 for women. Table 1. Mean, standard deviation, and correlation matrix (n = 282) 1 2 3 4 5 6 7 1. IESint – .13⁎ −.03 .41⁎⁎ .55⁎⁎ .47⁎⁎ .35⁎⁎ 2. Gender – .08 .06 .14⁎⁎ .08 .05 3. Age – .02 −.06 −.02 −.05 4. BDI-II – .47⁎⁎ .46⁎⁎ .35⁎⁎ 5. WBSIsup – .66⁎⁎ .33⁎⁎ 6. NRTS – .29⁎⁎ 7. DES – Mean 14.5 1.7 20.6 14.4 30.5 23.3 16.5 SD 8.7 0.5 4.9 9.5 9.7 8.7 12.7 Note: IESint = a subscale measuring intrusive symptoms of Impact of Event Scale; BDI-II = Beck Depression Inventory-II; WBSIsup = a subscale measuring thought suppression of White Bear Suppression Inventory; NRTS = Negative Rumination Trait Scale; and DES = Dissociative Experiences Scale. ⁎ p < .05. ⁎⁎ p < .01. Table options Next, a hierarchical multiple regression analysis was performed in order to test the hypothesis that avoidant tendencies have a significant influence on the intrusion of negative memories even when depressive symptoms are controlled. The IESint served as a dependent variable. In terms of predictive variables, the variables of age and gender were entered into the equation at the first step (Model 1), the BDI-II was done at the second step (Model 2), and the WBSIsup, the NRTS, and the DES were done at the final step (Model 3). The result in the final model showed that avoidant tendencies added statistically significant additional variance to the IESint beyond and above the BDI-II (ΔR2 = .18, p < .01; adjusted total R2 = .35, F(6, 275) = 26.3, p < .01). The effects of all the avoidant tendencies were significant, but the effect of the WBSIsup was the strongest. See the WBSIsup (β = .35, p < .01), the NRTS (β = .13, p < .05), and the DES (β = .15, p < .01) ( Table 2). Table 2. Multiple regression statistics for IESint (n = 282) Variables ΔR2 β Model 1 .02 Gender .13⁎ Age −.04 Model 2 .16⁎⁎ Gender .11⁎ Age −.05 BDI-II .41⁎⁎ Model 3 .18⁎⁎ Gender .06 Age −.01 BDI-II .13⁎ WBSIsup .35⁎⁎ NRTS .13⁎ DES .15⁎⁎ Note: IESint = a subscale measuring intrusive symptoms of Impact of Event Scale; BDI-II = Beck Depression Inventory-II; WBSIsup = a subscale measuring thought suppression of White Bear Suppression Inventory; NRTS = Negative Rumination Trait Scale; and DES = Dissociative Experiences Scale. ⁎ p < .05. ⁎⁎ p < .01.