Journal of Experimental Psychopathology. Past- and Future-based Rumination and its Effect on Catastrophic Worry and Anxiety

Transcription

1 Journal of Experimental Psychopathology JEP Volume Sample (2010) Issue 1, ISSN Past- and Future-based Rumination and its Effect on Catastrophic Worry and Anxiety Andy P. Field, Emma St. Leger & Graham C. L. Davey School of Psychology, University of Sussex, Brighton, UK Abstract This paper describes two experiments designed to investigate the role of cognitive rehearsal (rumination) in the enhancement of self-reported and physiological phobic fear and catastrophic worrying in spider fearful and non-fearful individuals. The results of these experiments demonstrate that (1) self-reported and physiological phobic fear is enhanced by rumination about the consequences of interacting with a phobia-related stimulus but not by rumination about the consequences of interacting with a nonthreatening stimulus, (2) this rumination also significantly increases catastrophic worry about the consequences of future interactions with a phobia-related stimulus; and (3) the fear- and catastrophic worry-enhancing effects of this rumination were found only in fearful individuals. These findings extend theoretical suggestions that rehearsing the negative outcomes of a phobia-related encounter should enhance fear during subsequent encounters (e.g. Davey, 1995, 1997; Field & Davey, in press). In addition, they suggest a link between the natural ruminative process in phobics and catastrophic worry processes. Copyright 2009 Textrum Ltd. All rights reserved. Keywords: Cognitive Rehearsal; Rumination; Catastrophic Worrying; Anxiety Disorders Correspondence to: Dr. Andy P. Field, School of Psychology, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QH, UK. andyf@sussex.ac.uk Received [date]; received in revised form [date]; accepted [date] Introduction Rumination has been characterised as a class of conscious thoughts that recur in the absence of environmental demands requiring such thoughts and that revolve around a common instrumental theme (Martin and Tesser, 1996). According to Martin and Tesser (1996) rumination has several important characteristics. First, ruminations can be goal-directed (attainment-focussed) or can focus on potential problems inherent in attaining a goal (discrepancy-focussed). Second, ruminative thoughts, because they typically engender failed attempts to reach some goal, invariably evoke negative emotional reactions. Third, rumination consumes cognitive resources at the expense of other cognitive processes (Martin and Tesser, 1989). Finally, rumination should be self-ceasing because people will be motivated to stop to avoid the negative emotions that it evokes (Wegner & Gold, 1995).

2 In theoretical terms rumination has been seen as both a problem-solving behaviour (Martin & Tesser, 1989) and a method of trauma management (Horowitz, 1986; Janoff-Bulman, 1979, 1989, 1992). Martin and Tesser (1989) propose that in its basic form rumination is merely cognitive rehearsal about some outcome (usually a desirable goal), which may lead to either problem-solving behaviour or, if the problem cannot be solved, learned-helplessness and depressive symptoms. Similarly, Horowitz (1986) and Janoff-Bulman (1979, 1989, 1992) have developed stress-response models of rumination. In both theories cognitive rehearsal of a trauma is seen as a process through which interpretation and resolution of that trauma occurs: rehearsal facilitates the revision of relevant schemata to incorporate information from the trauma and generate solutions to conflicts arising from the trauma (see Greenberg, 1995 for a review). All of these theories share the common assumption that some degree of ruminative thought is a normal and adaptive process (either as a response to stress, a means of goal attainment, or both) but that if this thinking process fails to reach a natural closure, it can be maladaptive. This idea fits well with research in both clinical and non-clinical populations that shows that high levels of rumination are an integral cognitive process in psychopathology. For example, (1) sufferers of obsessive compulsive disorder (OCD) frequently report unwanted, repetitive and intrusive thoughts, images and impulses (Foa & Kozak, 1995; Salkovskis, 1999); (2) sufferers of generalized anxiety disorder (GAD) typically suffer repetitive and uncontrollable ruminations about the sources of anxiety (Marks, 1987; Mathews, 1990); (3) contemporary models of anxiety-acquisition incorporate rumination as a contributing factor (e.g., Davey, 1997, Field & Davey, in press); (4) rumination might be an important trait vulnerability characteristic in dysphoria (Roberts, Gilboa, & Gotlib, 1998); (5) rumination is associated with cortisol secretion during stress (Roger and Najarian, 1997); and (6) rumination can enhance the retrieval of negative memories (Lyubomirsky, Caldwell & Nolen-Hoeksema, 1998). However, little research to date has investigated how the content of these ruminations might exacerbate anxiety. Rumination and the Enhancement of Fear A number of studies have provided insight into the possible contribution of rumination to the enhancement of anxiety. Davey (1995) suggested that rumination about the outcome of an interaction with a fear-evoking stimulus should enhance fear about that stimulus (see also Harvey, Richards, Dziadosz, and Swindell, 1993). Indeed, laboratory studies have shown that (1) cognitive rehearsal (an analogue of rumination) of the possible outcomes of a phobia-related encounter (UCS Rehearsal) can exacerbate anxiety towards the fear-evoking stimulus (Davey & Matchett, 1994; Ehlers, 1993, Jones and Davey, 1990); (2) rumination about an anxiety-provoking event seems to maintain anxiety compared to a distraction task (Blagden & Craske, 1996); and (3) anxiety-related thoughts (as seen in anxiety disorders) typically focus on the consequences of real-life problems whereas obsessive intrusive thoughts (as seen in obsessive compulsive disorder) focus on what the thought content implies about one's personal character (Clark and Claybourn, 1997). Therefore, rumination about the consequences of an interaction with a fear-evoking stimulus appears to contribute to the maintenance and enhancement of anxiety. Although this work has shown that rumination about the outcomes of a phobia-related encounter has an effect on anxiety, little work has investigated the relationship between rumination and catastrophic worry. Like rumination, worry is a repetitive, iterative and somewhat uncontrollable thought process and is similarly associated with anxiety (Davey & Tallis, 1994), and depression (Borkovec, 1994). However, rumination and worry can be distinguished in terms of their frequency, duration, ratio of verbal to visual image content, interference, egodystonic nature, and elicited emotions (Langlois, Freeston & Landouceur, 2000); worry is typically expressed verbally, is more distracting, more realistic, more

3 voluntary and is associated with a stronger urge to act (Wells & Morrison, 1994) whereas ruminations are typically egodystonic, can occur through images and impulses as well as verbal thought, and are more intrusive (Turner, Beidel, & Stanley, 1992). Worry also appears to focus on future events (Borkovec, 1994; MacLeod, 1994) whereas rumination typically focuses on past events and experiences (Martin & Tesser, 1989). An extreme form of worry is catastrophic worry, in which a person exaggerates the potential negative outcomes of a situation (see Davey & Levey, 1998). In the pain literature, catastrophizing has been characterised as a multidimensional construct comprising rumination (thinking about the pain itself), magnification (thinking about whether something serious might happen) and helplessness (feeling overwhelmed by thoughts) (see Sullivan, Bishop & Pivik, 1995; Sullivan & Neish, 1998). The implication in this model is that rumination leads to a catastrophic magnification in negative thought content. Although past research has shown that rumination about the outcomes of phobia-related encounters can inflate self-reported anxiety, there is no research indicating whether rumination actually leads to a magnification of the severity of the outcomes imagined (as predicted by Sullivan et al. s model). This study investigates the relationship between rumination (cognitive rehearsal) of an encounter with a fearevoking stimulus and catastrophic thought processes. The experiments combine features of both the rumination and catastrophic worry literatures to see whether rumination leads to a magnification in the severity of thought content (in terms of catastrophic worry). It is hypothesised that rumination following a phobia-related encounter will maintain or increase anxiety following a subsequent interaction with the phobia-related stimulus. In addition, it is predicted that this increase in anxiety will be accompanied by an increase in the number of catastrophic thoughts about future encounters with phobia-related stimuli. EXPERIMENT 1 Method Participants Participants were screened using Watts and Sharrock s (1984) Spider Phobia Questionnaire (SPQ). 250 questionnaires were completed and participants were selected from the upper and lower quartiles (20 from each). Forty students from Royal Holloway, University of London who expressed either high (N = 20) or low (N = 20) fear of spiders were used. Participants had a mean age of 23.3 (SD = 8.90 yrs.). Data from two of the 20 spider-fearful were not analysed because their scores on the SPQ at test indicated that they no longer met the criterion for being classified as fearful. The spider-fearful group had a mean SPQ score of (SD = 7.10, Range 15-38), which compares with means of and found in two groups of spider phobics who fulfilled DSM-III-R criteria for simple phobia (using SCID) (Thorpe & Salkovskis, 1995, 1997). The non-fearful group had a mean SPQ score of 6.15 (SD = 2.81, Range 3-6). SPQ scores were significantly different between fearful and non-fearful groups, t(24.83) = 9.1, p <.001. The mean PSWQ scores were (SD = 13.60) for the spider fearful individuals and (SD = 13.83) for the non-fearful individuals, t(37) = 1.91, p <.05. Materials The Spider Phobia Questionnaire, SPQ (Watts and Sharrock s, 1984): The SPQ was used to screen participants; it contains 43 items requiring a Yes/No response. The Penn State Worry Questionnaire, PSWQ (Meyer, Miller, Metzger & Borkovec, 1990): The PSWQ was used to measure trait worry; it contains 16-items with a Likert response scale. The PSWQ has been

4 found to possess high internal consistency in both college samples (e.g. Davey, 1993; Ladouceur, et al., 1992) and in a large sample of mixed anxiety disorders and GAD clients (Brown, Antony & Barlow, 1992). Furthermore, test-retest studies have shown that the PSWQ is stable over time (e.g. Ladouceur et al., 1992; and Meyer et al., 1990). A 25 17cm colour picture of a spider was used in the experiment. Design & Procedure The design was a 2 (fearfulness: fearful vs. non-non-fearful) 2 (animal rehearsed: spider or nonthreatening animal) 2 (time: rating before rumination vs. rating after rumination) 2 (animal catastrophized: spider vs. non-threatening) mixed design with the last two variables as repeated measures. Trait worry scores (from the PSWQ) were used as a covariate in the analysis of catastrophizing steps. Procedure First, participants were split into two groups; spider-fearful and non fearful (see criteria above). The procedure was as follows: Stage 1 (Pre-experimental assessment): All participants completed the SPQ and the PSWQ prior to the experiment. Stage 2 (Pre-rumination): Participants looked at a colour photo of a spider for 10 seconds directly after which they indicated how anxious the picture made them feel on a visual analogue scale (VAS) ranging from 0 (not at all anxious) to 100 (very anxious indeed). Stage 3 (Rumination): At this stage, both fearful and non-fearful groups were split into two sub-groups. Condition 1 (Rumination of Spider): One group of participants were asked to write down an example of what might happen to them that would make them anxious upon coming into contact with the spider in the picture. They were then asked to mentally rehearse this anxiety-inducing consequence for 2 minutes. Condition 2 (Rumination of Pet/ Non-Threatening Animal): The remaining participants in each group were asked to imagine the consequences of interacting with an animal that they liked (of which they were not scared), or a pet that they once owned. They rehearsed the consequence of this interaction for 2 minutes. Stage 4 (Post-rumination) This stage was identical for all participants. As in stage 2, participants looked at the picture of the spider for 10s and then indicated how anxious the picture made them feel using the VAS described before. Stage 5 (Catastrophizing): Participants were given 2 catastrophizing procedures (counterbalanced) in which they were asked what would worry them about a future interaction with the spider (or pet) (Davey & Levey, 1998; Vasey and Borkovec, 1992). The catastrophizing measure is a well-established interview technique (see, for example, Davey & Levey, 1998; Vasey & Borkovec, 1992) and was used to assess the degree to which participants were worrying catastrophically about the future consequences of interacting with a spider/non-threatening animal. There were two catastrophizing interviews done, one that related to a future encounter with a spider, and one that related to an encounter with a pet, or nonthreatening animal. The experimenter began the catastrophizing interview by asking the participant: What is it that worries you about interacting with the spider (or pet)? The participant then wrote down their worry and verbally reported this worry to the experimenter. The Experimenter then asked What is it

5 that worries you about X?, where X is the worry that the participant had just reported. The participant then wrote down and verbally reported this new worry. The experimenter then asked What is it that worries you about X?, where X was the new worry. This procedure continued until either the participant (a) was unable to report a new worry or (b) repeated the same worry more than twice. Results Anxiety data Figure 1 shows the average self-reported anxiety after seeing the picture of the spider by participants both before and after rumination about the consequences of an interaction with either a spider or a nonthreatening animal. Non-fearful participants showed the same pattern of results regardless of the type of animal about which they rehearsed: In both cases anxiety evoked by the spider picture decreased across the experiment. This result is expected because familiarity with the picture should result in lowered arousal to it. The spider-fearful group responded quite differently: after ruminating about the consequences of interacting with a non-threatening animal, spider-fearful participant s anxiety towards the spider picture reduced substantially, probably due to habituation towards the stimulus material. More important, after rehearsing interacting with a spider, their anxiety levels increased Pre-Rehearsal Post-Rehearsal Mean Self-Reported Anxiety Spider Pet Spider Pet Spider Fearful Spider Nonfearful Figure 1 Graph to show the mean (and SEM) self-reported anxiety pre- and post-rehearsal split according to the type of animal rehearsed (spider or non-threatening (pet)) and whether participants were spider fearful or nonfearful. Self-reported anxiety was analysed using a fearfulness (spider fearful vs. non-fearful) animal rehearsed (spider vs. non-threatening) time (pre- vs. post-rumination) three-way mixed ANOVA with repeated measures on the last variable. There were no significant effects of time, F(1, 34) = 1.16, ns, or animal rehearsed, F < 1. There was a significant main effect of fearfulness, F(1, 34) = , p <.001, indicating that in general spider-fearful participants were more anxious than non-fearful participants. The time animal rehearsed, F(1, 34) = 3.54, p =.068, and fearfulness animal rehearsed, F(1, 34) = 3.12, p =.086, interactions both approached significance, indicating that the content of rumination had some effect on anxiety, albeit non-significantly. A significant three-way interaction, F(1, 34) = 4.94, p <.05, indicated that differences in anxiety to the spider picture when the consequences of interacting with a

6 spider were rehearsed relative to when a non-threatening animal was rehearsed were significantly different in spider-fearful participants compared to non-fearful. Specifically, contrasts revealed that the effect of rumination on subjective anxiety over time was significant for spider-fearful participants, F(1, 16) = 5.97, p <.05, but not for non-fearful participants, F < 1. Due to the subjective nature of the rating scale and differences in the magnitudes that people might use to express increases or decreases in anxiety, a logistic regression analysis was carried out to see whether anxiety increased or decreased as a result of the experimental manipulations (see Field, 2000). The outcome variable was whether anxiety increased or decreased and the predictor variables were the type of animal rehearsed (spider or non-threatening), whether the participant was fearful (yes/no) and the interaction of these two variables. The only significant predictor was the interaction of the type of animal rehearsed and whether the person was fearful, -2LL = 8.2, p <.01; Nagelkerke R 2 = 0.26; Exp (B) = 9.33, CI 0.95 = 1.8 (lower), (Upper). This result showed that spider-fearful participants who rehearsed the consequences of interacting with a spider were 9 times more likely to show increased anxiety compared to non-fearful participants. Catastrophizing data Figure 2 shows the average number of catastrophizing steps for each participant when catastrophizing about the consequences of interacting with a spider or non-threatening animal. Non-fearful participants showed the same pattern of results regardless of the type of animal involved in the rumination: in both cases they catastrophized slightly more about the consequences of interacting with a pet, or nonthreatening animal. This result is expected because familiarity with the animal should mean that participants have experience of imagining the consequences of interacting with that animal. What's more, it is likely that they will have previously generated numerous scenarios associated with the animal (see Davey and Levey, 1998). The spider fearful participants, however, responded differently: after ruminating about the consequences of interacting with a non-threatening animal, they behaved like nonphobics: they generated more worrisome thoughts about that animal than about the spider. However, after ruminating about interacting with a spider, they generated more worrisome thoughts about spiders than about their non-threatening animal. This finding was not true of non-fearful participants. The catastrophizing steps were analysed using a fearfulness (spider-fearful vs. non-fearful) animal rehearsed (spider vs. non-threatening) animal catastrophized (spider vs. non-threatening) three-way mixed ANCOVA with PSWQ scores as a covariate. Analysis revealed a significant 2-way animal rehearsed animal catastrophized interaction, F(1, 43) = 6.17, p <.05, indicating that the type of rumination in which participants engaged had a significant differential effect on the level of catastrophizing. However, the significant 3-way interaction, F(1, 34) = 4.45, p <.05, showed that this two-way interaction was the result of a differential effect of rumination in the fearful participants but not the non-fearful participants. Specifically, the non-fearful participants were unaffected by the rumination in which they engaged, F < 1. However, spider-fearful participants were affected: spider-related rumination lead to increased catastrophizing about future interactions with spiders compared to non-threatening animals, F(1, 16) = 7.65, p <.05. There was no effect of trait worry on these results, F(1, 34) = 3.30, ns. In addition, rehearsing an encounter with a non-threatening animal produced greater catastrophizing about that animal than the spider in both spider-fearful, t(9) = 2.39, p <.01, and non-fearful, t(9) = 3.07, p <.01, individuals. However, ruminating about a spider encounter seemed to significantly suppress the degree of catastrophizing about encountering a fear-irrelevant animal in spider-fearful individuals, t(8) = 1.92, p <.05, but not in non-fearful individuals, t < 1. These results show that the pattern of responding shown in Figure 2 is significant and that trait worry does not contribute to the

7 finding in any way. Therefore, differences in the degree of catastrophic worry can be attributed only to the experimental manipulations. 20 Catastrophizing Spider Catastrophizing Pet Mean Catastrophizing Steps Spider Pet Spider Pet Spider Fearful Spider Nonfearful Figure 2 Graph to show the mean (and SEM) number of catastrophizing steps produced by participants split according to the type of animal rehearsed (spider or non-threatening (pet)) and whether participants were spider fearful or non-fearful. Summary These results suggest that for non-fearful participants, rumination has little effect on the generation of catastrophic worries, and anxiety. However, for spider-fearful participants, rumination about a spider increased anxiety and catastrophic worry about the spider relative to a non-threatening animal. Interestingly, cognitive rehearsal of a non-threatening animal seemed to (a) slightly suppress anxiety about the spider (although this suppression is likely to be habituation to the stimulus material) and (b) produce no increase in worry about the spider in fearful compared to non-fearful participants. Discussion In spider-fearful participants, ruminating about the negative consequences of interacting with a spider seems to have two effects: (1) it increases anxiety relative to non-fearful individuals; and (2) it increases the number of catastrophic thoughts about future encounters with spiders relative to non-threatening animals. Rumination about an encounter with a non-threatening animal decreases anxiety and enhances catastrophic thinking about that non-threatening animal. In non-fearful individuals ruminating about the consequence of interacting with either a spider or a non-threatening animal produced no change in anxiety or catastrophizing. These findings suggest that ruminating about a threatening stimulus leads to greater catastrophic worry in people already fearful of that stimulus. Therefore, following rumination about an outcome of interacting with a spider, spider-fearful individuals blow the consequences of future

8 interactions out of proportion: these individuals imagine that the consequences of future encounters will be worse than they are actually likely to be. The anxiety data support past work, which has shown that ruminating about an aversive event can maintain and enhance anxiety (Davey & Matchett, 1994; Ehlers, 1993, Jones and Davey, 1990), and that rehearsing the consequences of an interaction with a fear-relevant stimulus enhances anxiety (Field, 1999). The worry data seem to suggest that rumination about a phobia-related encounter can lead to catastrophic thoughts about future encounters. The results of this study seemed to indicate that compared to non-fearful participants, spider-fearful individuals produce more catastrophic thoughts about spiders compared to a non-threatening animal after ruminating about a phobia-related encounter. However, after ruminating about a non-threatening encounter both spider-fearful and non-fearful individuals generated more catastrophic thoughts about a future interaction with a non-threatening animal. One possible explanation is simply that spider-fearful individuals have had more practice at generating spider-related scenarios and hence can more easily catastrophize about spiders than nonfearful individuals. However, spider-fearful individuals generate less spider-related catastrophizing steps after ruminating about a non-threatening animal, therefore, it seems that phobia-related rumination is necessary to elicit catastrophic fear-related scenarios. In addition, spider-fearful individuals produced a similar number of spider catastrophizing steps to non-fearful individuals after ruminating about a spider, but produced more steps relative to the number generated about a non-threatening animal. The possibility that spider-fearful individuals simply have more experience of generating catastrophic spiderrelated scenarios does little to explain why catastrophizing about a non-threatening animal is suppressed after fear-related rumination. The suppression of catastrophic thoughts about non-threatening animals seen in phobics mimics a phenomenon observed by Cavanagh and Davey (2000) who found that spiderfearful individuals significantly underestimated the likelihood of aversive consequences following fearirrelevant stimuli. Although Cavanagh and Davey found this effect even after contrast effects were ruled out, the possibility remains that the effects observed in the present study reflect a contrast effect produced by having participants sequentially catastrophize about both a fear-relevant and fear-irrelevant scenario. Experiment 2 The evidence from Experiment 1 suggests that ruminating the consequences of a fear-related encounter enhances self-reported anxiety and leads to greater catastrophic worry. However, there were several limitations to this experiment. First, participants were not specifically told on what to base their rumination. Participants were instructed merely to think of an anxiety-evoking consequence of interacting with a spider. There are two possibilities: individuals based their consequence (and hence rumination) on (1) actual past events that they had experienced (a past-based rumination), or (2) what they would most likely expect to happen hypothetically in a future encounter (a future-based rumination). If participants used the later strategy then there are at least two implications. First, catastrophic worry is typically future-based (Borkovec, 1994; MacLeod, 1994), yet rumination is usually based on past experience (Martin & Tesser, 1989). Therefore, if individuals ruminated about a hypothetical encounter, then Experiment 1 may lack ecological validity because in reality rumination would be based on past experience. An ecologically valid demonstration of a link between rumination and catastrophic worry would, therefore, need to show the effects when rumination is specifically based on past experience. Second, if individuals based rumination on a hypothetical encounter (rather than past experience) then catastrophic worry may have increased simply because fearful individuals used the rumination task to generate hypothetical catastrophic outcomes that they then reported later in the experiment.

9 A second limitation of Experiment 1 is that the effects of rumination on catastrophic worry were demonstrated in a procedure in which individuals sequentially catastophized about future interactions with a spider or non-threatening animal. To eliminate the possible contrast effects created by this design, Experiment 2 required individuals to catastrophize only future interactions with the animal about which they had just ruminated. Finally, Experiment 1 used only self-report measures of anxiety. Although these methods are commonly used and accepted indicators of anxiety (e.g. Blagden & Craske, 1996; Lyubomirsky et al., 1998; Nolen- Hoeksema & Morrow, 1993) they can be influenced by conscious factors (such as hypothesis guessing). Although research has shown physiological changes due to rumination (e.g. Davey & Matchett, 1994; Jones & Davey, 1990) additional physiological data would provide a useful confirmation of the self-report responses and help rule out effects of demand awareness. Experiment 2 is, in essence, a replication of Experiment 1 that attempts to address some of these limitations. Primarily, this experiment distinguished between whether participants engage in past- or future-based rumination. In addition, heart rate data were collected to verify the responses from VAS anxiety. Finally, to rule out contrast effects, individuals were asked only to catastrophize about interactions with the animal that had previously been the focus of their rumination. Method Participants The Spider Phobia Questionnaire (SPQ) (Watts & Sharrock, 1984) was used to screen participants. A total of 161 questionnaires were distributed to the employees of four different companies and 114 questionnaires were returned completed. From the 114 questionnaires received, 40 participants were chosen as candidates for the study. The 20 highest scoring participants were chosen as fearful participants and the 20 lowest scoring participants were the non-fearful participants. The non-fearful sample had a mean age of (SD = 9.62) and the fearful sample had a mean age of (SD = 8.44). The non-fearful group had a mean SPQ score of 5.55 (SD = 1.36, Range 3-7) compared to (SD = 5.45, Range 20-39) in the spider-fearful group, difference between groups t(21.344) = , p <.001. These values again compare with means of and found spider-phobes who fulfilled DSM-III-R criteria for simple phobia (Thorpe & Salkovskis, ). The mean PSWQ scores were (SD = 9.99) for the spider fearful individuals and (SD = 11.42) for the non-fearful individuals, t(38) = 2.17, p <.05. Materials The same materials as in Experiment 1 were used in the present experiment. Unlike Experiment 1, two measures of anxiety were used to balance a subjective measure (a self-report anxiety scale) with a more objective measure (heart rate). The anxiety VAS was the same as in Experiment 1. While the participants were making their ratings on the self-report measure a pulse monitor recorded the participant s heart rate. The pulse monitor was attached to the participant s ear at the beginning of the experiment and their pulse was monitored at four different stages during the experiment: (1) preexperiment: at the beginning while completing the questionnaires; (2) after picture 1: directly after seeing the spider picture for the first time (while participants gave their first VAS rating); (3) during rumination: half way though a participant s period of rumination; and (4) after picture 2: directly after seeing the spider picture for the second time (while participants made their second VAS rating).

10 Design For the self-report anxiety the design was a 2 (fearfulness: fearful vs. non-fearful) 2 (rumination type: past vs. future) 2 (animal rehearsed: spider vs. non-threatening) 2 (time: pre- vs. post-rumination), mixed design with repeated measures used for the last two variables. For the heart rate data the design was the same but the time variable had 4 levels. For the catastrophizing data there was no time variable and trait worry scores (from the PSWQ) were used as a covariate. Procedure As in Experiment 1, participants were split into two groups: spider-fearful and non fearful (see criteria above). Each participant went through the experimental procedure twice: once ruminating about a spider encounter and once ruminating about a non-threatening animal or pet. The order in which participants completed the two procedures was counterbalanced. Assuming a participant ruminated about a spider first, the procedure was as follows: Stage 1 (Pre-experimental assessment): All participants signed a consent form before a heart rate monitor was attached to their ear. After 30s (to allow the reading to stabilise) the experimenter recorded the participant s baseline heart rate. Participants then completed the SPQ and the PSWQ. Stage 2 (Pre-rumination): All participants were shown a colour photo of a spider for 10 seconds directly after which their heart rate was recorded while they indicated how anxious the picture made them feel on a VAS ranging from 0 (not at all anxious) to 100 (very anxious indeed). Stage 3 (Rumination): At this stage, both fearful and non-fearful groups were split into two groups. Condition 1 (Rumination about a Past Interaction): The participants were asked to write down an example of a previous encounter that they had had with a spider that made them anxious. (All nonfearful participants were able to generate such an encounter). They then mentally rehearsed this past interaction for two minutes. After one minute their heart rate was measured. Condition 2 (Rumination about a Future Interaction): The remaining participants in each group were asked to write down an example of what might happen to them that would make them anxious upon coming into contact with the spider in the picture. Participants mentally rehearsed this scenario for two minutes. After one minute their heart rate was measured. Stage 4 (Post-rumination) This stage was identical for all participants. As in stage 2, participants looked at the picture of the spider for 10s after which their heart rate was measured and they indicated how anxious the picture made them feel using the VAS. Stage 5 (Catastrophizing): Participants were given a catastrophizing procedure that related to the consequences of interacting with a spider (see Experiment 1). Stage 6 (Replication with different animal): After completing this procedure each participant repeated the experiment except that during the rumination stage (stage 3) they rehearsed a past or future interaction (depending on the group to which they were allocated) that had made them anxious involving a non-threatening animal or pet. All other procedural aspects were identical to those described except that during the catastrophizing stage, participants catastrophized an interaction with a non-threatening animal or pet. The order in which participants completed the two procedures was counterbalanced across participants.

11 Results Self-Reported Anxiety Data Figure 3 shows the change in average self-reported anxiety towards the spider picture for past- and future-based rumination about an encounter with a spider or a non-threatening animal (pet). Spider fearful individuals showed a dramatic increase in anxiety towards the picture after ruminating about a spider and maintained anxiety (or showed a decrease) after ruminating about a non-threatening animal. Non-fearful individuals showed very small changes in self-reported anxiety throughout. There seemed to be little difference between participants who ruminated a past experience compared to those that imagined a possible future encounter Rehearsing Future Consequences Pre-Rehearsal Post-Rehearsal Mean Self-Reported Anxiety Spider Pet Spider Pet Spider Fearful Rehearsing Past Consequences Spider Nonfearful Pre-Rehearsal Post-Rehearsal Mean Self-Reported Anxiety Spider Pet Spider Pet Spider Fearful Spider Nonfearful Figure 3 Graph to show the mean (and SEM) self-reported anxiety pre- and post-rehearsal split according to the type of animal rehearsed (spider or non-threatening (pet)), whether rehearsal was past- or future-based and whether participants were spider fearful or non-fearful. A 2 (fearfulness: fearful vs. non-fearful) 2 (rumination type: future vs. past) 2 (animal rehearsed: spider vs. non-threatening) 2 (time: pre- vs. post-rumination) mixed design ANOVA with repeated measures for the last two variables was used to analyse these data. An initial analysis included

12 counterbalancing order as an additional factor (whether the spider was rehearsed first or the nonthreatening animal) but revealed no main effect of order and no interactions involving order and time, all Fs < 1 1. The analysis revealed significant main effects of animal rehearsed, F(1, 36) = 17.46, p <.001, fearfulness, F(1, 36) = 52.81, p <.001, and time, F(1, 36) = 8.33, p <.01, indicating that, when all other factors are ignored, self-reported anxiety to the picture was significantly greater (1) when ruminating about a spider compared to a non-threatening animal; (2) in fearful compared to non-fearful individuals; and (c) after rumination compared to before. There was a significant animal rehearsed time rumination type interaction, F(1, 36) = 7.86, p <.01, indicating that the change in anxiety seen when people ruminate about a spider or a pet depended on the type of rumination engaged in. This reflects the fact that when a future consequence was rehearsed the change in anxiety after ruminating about a spider encounter compared to a non-threatening animal was much stronger, F(1, 18) = 35.41, p <.001, than when the consequences of a past encounter were rehearsed, F(1, 18) = 4.41, p =.05. As predicted, there was a significant animal rehearsed fearfulness interaction, F(1, 36) = 17.04, p <.001, demonstrating that when the time at which anxiety is measured is ignored, the type of animal rehearsed had a different effect on spider-fearful and non-fearful individuals. For spider-fearful participants anxiety was higher in the spider-rehearsal condition compared to the pet-rehearsal but for non-fearful individuals there was no difference. More important, there was a significant animal rehearsed fearfulness time interaction, F(1, 36) = 21.61, p <.001. This effect shows that the change in selfreported anxiety seen in spider-fearful and non-fearful individuals was different and depended on the type of animal that was rehearsed. For non-fearful individuals there was no significant change in anxiety after ruminating about a spider compared to a non-threatening animal, F < 1, but in spider fearful individuals the change was highly significant, F(1, 18) = 37.02, p <.001. The animal rehearsed time fearfulness rehearsal type interaction was not significant (F < 1) indicating that the type of rumination did not affect the predicted results shown up by the animal rehearsed time fearfulness interaction. In other words, the differential effect on anxiety of ruminating about a spider compared to a non-threatening animal in spider-fearful compared to non-fearful individuals was not affected by whether the rumination was past- or future-based. All other main effects and interactions were non-significant. Heart Rate Data Figure 4 shows the change in average self-reported anxiety towards the spider picture for past- and future-based rumination about a spider or a non-threatening animal (pet). For spider-fearful individuals ruminating about a spider there was a steady increase in heart rate from baseline through the first viewing of the spider picture, through rehearsal and to the second viewing of the picture. This is true both when rumination was past- and future-based. When these individuals ruminated about a non-threatening animal, their heart rates again increased after viewing the spider picture for the first time but reduced during rehearsal and showed little subsequent increase after viewing the picture for the second time. Non-fearful individuals showed relatively little change in heart rate throughout. A 2 (fearfulness: fearful vs. non-fearful) 2 (rumination type: future vs. past) 2 (animal rehearsed: Spider vs. non-threatening) 4 (time: baseline, after first picture 1, during rumination and after the 1 Time is a crucial factor because it represents the change in self-reported anxiety due to rehearsal.

13 picture 2) mixed design ANOVA with repeated measures for the last two variables was used to analyse these data. Heart Rate (Beats per Minute) Rehearsing Future Consequences Pre-Experiment After Picture (1) During Rehearsal After Picture (2) 50 Heart Rate (Beats per Minute) Spider Pet Spider Pet Spider Fearful Rehearsing Past Consequences Spider Nonfearful Pre-Experiment After Picture (1) During Rehearsal After Picture (2) 50 Spider Pet Spider Pet Spider Fearful Spider Nonfearful Figure 4 Graph to show the mean (and SEM) number of catastrophizing steps produced by participants split according to the type of animal rehearsed, whether rehearsal was past- or future-based and whether participants were spider fearful or non-fearful. Effects involving time, W = 0.65, χ 2 = 14.80, df = 5, p <.05, and the animal rehearsed time interaction, W = 0.52, χ 2 = 22.94, df = 5, p <.001, violated the assumption of sphericity and so Greenhouse-Geisser corrected values are reported. The analysis revealed significant main effects of animal rehearsed, F(1, 36) = 5.60, p <.05, and time, F(2.51, 90.31) = 18.15, p <.001, indicating that, when all other factors are ignored, heart rates to the picture were significantly higher (1) when ruminating about a spider compared to a non-threatening animal; and (2) at different stages of the experiment. There were significant interactions between time fearfulness, F(2.51, 90.31) = 9.06, p <.001, and animal rehearsed time, F(2.13, 76.58) = 12.45, p <.001.

14 As with the self-report data, there was a significant animal rehearsed fearfulness interaction, F(1, 36) = 7.37, p <.01, demonstrating that when the time at which anxiety is measured is ignored, the type of animal rehearsed had a different effect on spider-fearful and non-fearful individuals. For spider-fearful participants heart rates were higher in the spider-rehearsal condition compared to the pet-rehearsal but for non-fearful individuals there was no difference. More important, there was a significant animal rehearsed fearfulness time interaction, F(2.13, 76.58) = 4.94, p <.01. This effect shows that the change in heart rates seen in spider-fearful and non-fearful individuals was different and depended on the type of animal that was rehearsed. For non-fearful individuals there were no significant changes in heart rate when ruminating about a spider, F(1.83, 34.71) = 1.78, ns, but in spider fearful individuals there were highly significant changes, F(2.09, 39.65) = 23.64, p <.001. For the spider-fearful group there was a highly significant linear trend across the four heart rate measurements, F(1, 16) = 63.33, p <.001, indicating a linearly increasing heart rate from baseline through seeing the picture, through ruminating an interaction until after seeing the picture again. No such trend was present for the non-fearful group, F(3, 57) = 1.23, ns, of for either group when rehearsing a non-threatening animal, both Fs < 1. Further contrasts across the trend revealed that for fearful individuals there was a significant increase in heart rate from baseline to viewing the spider picture for the first time, F(1, 19) = 9.94, p <.01, no subsequent increase while rehearsing an interaction with the spider, F(1, 19) = 1.42, ns, but a highly significant increase when viewing the spider picture for the second time, F(1, 19) = 28.95, p <.001. For non-fearful individuals there was no significant change in heart rate from baseline to viewing the spider picture for the first time or during subsequent rehearsal, both Fs < 1, or when viewing the spider picture for the second time, F(1, 19) = 3.65, ns. When ruminat8ing about an interaction with a non-threatening animal there were significant changes in heart rate for both fearful, F(1.96, 37.32) = 6.99, p <.01, and non-fearful, F(2.25, 42.68) = 4.34, p <.05, participants. Further contrast revealed that for fearful individuals there was a significant increase in heart rate from baseline to viewing the spider picture, F(1, 19) = 11.90, p <.01, a significant decrease during rehearsal of the pet, F(1, 19) = 8.07, p <.01, and no significant change when viewing the spider picture for the second time, F(1, 19) = 3.29, ns. For non-fearful individuals there was a significant increase in heart rate from baseline to viewing the spider picture, F(1, 19) = 4.70, p <.05, a significant decrease during rehearsal of the pet, F(1, 19) = 18.26, p <.001, and a significant increase when viewing the spider picture for the second time, F(1, 19) = 7.52, p <.05. The animal rehearsed time fearfulness rumination type interaction was not significant (F < 1) indicating that the type of rumination does not affect the results shown by the animal rehearsed time fearfulness interaction described above. The differential effect on heart rate of ruminating about a spider compared to a non-threatening animal in spider-fearful compared to non-fearful individuals was not affected by whether the rehearsal was past- or future-based. All other main effects and interactions were non-significant. Catastrophizing Data Figure 5 shows the average number of catastrophizing steps for each participant when catastrophizing about the consequences of interacting with a pet or a spider when the rumination was past- or futurebased. Non-fearful participants showed the same pattern of results regardless of the type of animal involved when the rumination was past-based but more catastrophizing steps about the spider than the non-threatening animal when rumination was future-based. The spider fearful participants, however, responded differently: they generated many catastrophizing steps after ruminating about a spider but virtually none after ruminating about a non-threatening animal.

15 15 Catastrophizing Spider Catastrophizing Pet Mean Catastrophizing Steps Past Future Past Future Spider Fearful Spider Nonfearful Figure 5 Graph to show the mean (and SEM) heart rate at baseline, pre-rehearsal, during rehearsal and postrehearsal split according to the type of animal rehearsed, whether rehearsal was past- or future-based, and whether participants were spider fearful or non-fearful. The catastrophizing steps were analysed using a fearfulness (spider-fearful vs. non-fearful) rumination type (past- vs. future-based) animal catastrophized (spider vs. non-threatening) three-way mixed ANCOVA with PSWQ scores as a covariate. The main effects of animal catastrophized, F(1, 35) = 10.70, p <.01, and fearfulness, F(1, 35) = 78.32, p <.001, were significant indicating that significantly more catastrophizing steps were generated to the spider than the pet, and that fearful participants generated significantly more steps than non-fearful individuals. Important was the significant animal catastrophized fearfulness interaction, F(1, 35) = 97.28, p <.001, which showed that spider-fearful and non-fearful participants differed in the number of catastrophic thoughts generated about different animals. Specifically, when catastrophizing a non-threatening animal, spider-fearful and non-fearful participants produced a similar number of steps, F(1, 37) = 1.02, ns, however, when catastrophizing a spider, fearful individuals produced significantly more steps than non-fearful individuals, F(1, 35) = 99.15, p <.001. The non-significant animal catastrophized fearfulness rumination type interaction, F(1, 35) = 1.70, ns, showed that this pattern of responding was the same after both past-based and future-based rumination. There was no effect of trait worry on these results, F < 1. Summary These results support Experiment 1 in that ruminating about the consequences of interacting with a spider increased anxiety towards a picture of a spider in spider-fearful but not non-fearful individuals. Ruminating about a non-threatening animal reduced or maintained the anxiety evoked by a spider picture in fearful participants also. The heart-rate data provide greater insight into the effect that rumination has on anxiety. In spider-fearful participants rehearsing the consequences of interaction with

16 a spider successively increased anxiety during rumination and produced a significant increase upon subsequent contact with a picture of a spider. When a non-threatening animal was rehearsed heart rates dropped during rumination and remained lower than following the initial presentation of the picture. Spider-fearful individuals generated more catastrophic thoughts about spiders (after ruminating about a spider) than about a non-threatening animal (after ruminating about that animal). Non-fearful individuals showed no statistical differences in their catastrophizing of spiders vs. non-threatening animals. Whether rehearsal was past- or future-based had no significant effects on any of the results. Discussion Experiment 2 showed that both past- and future-based ruminating about the consequences of interacting with a fear-relevant stimulus significantly increased both self-reported anxiety and heart rate. This was true only for spider-fearful individuals. Ruminating about a past- or future-based interaction with a feared stimulus also led to increased catastrophizing about the feared stimulus. Ruminating about interactions with a non-threatening stimulus generally reduced the subsequent anxiety evoked by a feared stimulus (or prevented an increase) and led to no catastrophizing. The heart rate data suggest that although rumination itself increased fear, it also produced an additional significant increase in heart rate upon subsequent presentation of a fear-related stimulus. This suggests a process similar to incubation (Eysenck, 1979) in that fear increased upon subsequent presentations of the fear-evoking stimulus. However, additional data including several re-exposures to the fear-evoking stimulus would be necessary to verify this possibility. The catastrophizing data showed that spider-related catastrophizing was significantly greater in spiderfearful individuals (compared to non-fearful individuals) after ruminating about a spider-related encounter. This finding could be explained by spider-fearful individuals having had greater practice at generating negative consequences of spider interactions. This type of account has been ruled out when looking at the processes underlying catastrophic worry in worriers (see Davey & Levy, 1998). Davey and Levy found that worriers (based on PSWQ scores) possessed a general iterative style that they applied to novel situations. Although the current data showed effects independent of PSWQ scores, the spiderfearful groups had significantly higher PSWQ scores than the non-fearful groups 2 and so it might be reasonable to assume, based on Davey & Levy s findings, that the current results are due to rumination triggering a general iterative style of fear-congruent catastrophic thinking in anxious individuals. Interestingly, this catastrophic thinking was triggered by both past- and future-based rumination. Therefore, whether encountering an anxiety-inducing stimulus triggers rumination about actual anxietyevoking past encounters, or speculative what if rumination is unimportant in promoting catastrophic thought about what will happen in future encounters. This finding is important because it rules out the possibility that the enhancement of catastrophic worry in Experiment 1 was the result of fearful individuals generating catastrophic outcomes during the rumination part of the experiment (and, therefore, having time to generate a set of catastrophic outcomes prior to the catastrophizing measure). Finally, past-based rumination is a better analogue of naturally-occurring rumination (Martin & Tesser, 1989), therefore, Experiment 2 suggests that naturally-occurring rumination in anxious individuals leads to catastrophic worry about future interactions with an anxiety-evoking stimulus. 2 This finding is consistent with other anxiety disorders such as GAD in which worry is seen as an important diagnostic criterion