نقش محرک و بی قراری در سرگردانی ذهن در مورد گذشته، حال و آینده: یک مطالعه آزمایشگاهی

To bridge the related but separate areas of research on mind-wandering and Involuntary Autobiographical Memory (IAM), the frequency and temporal focus of task unrelated thoughts about past, present, and future was compared in 19 dysphoric and 21 non-dysphoric participants, using a modified laboratory method for studying IAMs. Participants were stopped 11 times during a 15-min vigilance task and recorded their thoughts at that moment. In both groups, most thoughts were spontaneous, task-unrelated, and triggered by irrelevant cue-words on the screen with negative words being more likely to trigger past memories and positive cues – thoughts about future. Both groups reported more past memories than current or future thoughts, but differences emerged in the type of future thought experienced: non-dysphoric participants reported more planning thoughts, and dysphoric participants more abstract hypothetical thoughts. The results suggest that some findings from IAM research regarding cues and the impact of dysphoria may be generalizable to mind-wandering.

Mind-wandering has been referred to as task unrelated thought (Giambra, 1989), task unrelated images and thoughts (Giambra, 1993 and Giambra, 1995) or stimulus-independent thought (Teasdale et al., 1995) among other names (see Smallwood & Schooler, 2006). Everyday examples range from fantasising about a luxury yacht voyage whilst stirring soup to ‘zoning-out’ when reading a boring text (Schooler et al., 2004 and Singer, 1976). One of the key characteristics of the phenomenon involves ‘decupling’ from one’s immediate environment, or “a shift in the focus of attention away from the here and now towards one’s private thoughts and feelings” (Smallwood, O’Connor, Sudbery, & Obonsawin, 2007, p. 818). In addition, the incidents of mind-wandering are often unintended, i.e., they occur spontaneously. Sometimes people may not even be aware that their mind has wandered until they are stopped and asked what their thoughts were at that moment (Schooler, 2002 and Smallwood et al., 2007). Finally, task unrelated thoughts are often considered to be stimulus independent, as they are thought to originate from internal rather than external sources (Stawarczyk, Majerus, Maj, Van der Linden, & D’Argembeau, 2011). Indeed, according to Singer (1993), “the human condition involves a continuing tension between processing information generated from the physical and social milieu and the continuous operation of centrally generated material from long-term memory in the form of reminiscences, wishes, current concerns, expectations and fantasies” (p. 100). There is near universal agreement that mind-wandering is both common and frequent in everyday life with some studies suggesting that up to half of our waking lives are spent thinking about matters other than what is immediately before us (Killingsworth & Gilbert, 2010). There is, however, an ongoing debate about its nature and role in mental life (Mooneyham and Schooler, 2013 and Smallwood, 2013) with some researchers arguing that mind-wandering represents a failure of executive control which may be detrimental to ongoing activities (McVay & Kane, 2010), while others suggest that it represents the redirection of executive resources toward internal goals when they are not required for completion of an external task, and may therefore have an adaptive function (Klinger, 1999, Klinger, 2013 and Smallwood and Schooler, 2006). This view is also supported by evidence showing that during mind-wandering people are more likely to think about future plans and tasks than about current and past events (Baird, Smallwood, & Schooler, 2011). Despite this tendency to prospect more often than retrospect, people do report thinking about the past during mind-wandering episodes (e.g., while sitting in a boring meeting, one may suddenly remember a skiing holiday in Switzerland). However, spontaneous remembering of past events without actively trying to remember anything has been termed Involuntary Autobiographical Memory (IAM) and studied as part of research on autobiographical memory with little overlap with research on mind-wandering (for exceptions see Finnbogadóttir and Berntsen, 2013, McVay and Kane, 2013, Song and Wang, 2012 and Vannucci et al., 2014). The aim of this paper is to take initial steps toward bringing together these two separate streams of research on mind-wandering and IAMs in the hope that this may provide interesting insights for both areas of research. If IAMs are instances of mind-wandering (cf. Johannessen & Berntsen, 2010), then one would expect that similar findings would be obtained in both areas of research in relation to several important variables. This is clearly the case with respect to the effects of attentional demands of ongoing tasks on the occurrence of mind-wandering and IAMs as both are less likely to occur with cognitively demanding rather than undemanding ongoing tasks (e.g., Antrobus, 1968, Berntsen, 1996, Giambra, 1995, Kvavilashvili and Mandler, 2004, Schlagman and Kvavilashvili, 2008, Smallwood et al., 2004 and Smallwood et al., 2003). However, discrepant findings have started to emerge with respect to several other variables. For example, research on IAMs, using both diary and laboratory methods has shown that the majority of IAMs (about 80–94%) are elicited by easily identifiable cues that are predominantly external rather than internal, and related to the central aspects of the content of IAMs (e.g., seeing balloons may elicit a memory about a particular birthday party) ( Berntsen, 1996, Mace, 2004, Mace et al., in press, Mazzoni et al., 2014 and Schlagman et al., 2007). Some studies have also shown the importance of verbal cues (both external and internal) in eliciting IAMs ( Mace, 2004, Schlagman and Kvavilashvili, 2008 and Schlagman et al., 2007). 1 In contrast, very little is known about the cues that directly trigger mind-wandering episodes (but see McVay and Kane, 2013 and Song and Wang, 2012), as participants are not asked to indicate if the thought they were having just before the probe was triggered by a particular cue (internal or external). Moreover, in the experience sampling study of Song and Wang (2012), which did query participants about the cues, it was found that although participants reported cues in 88% of thought probes, the percentage of internal cues (49%) was as high as external cues (51%), which is different from the predominance of external cues reported in the IAM literature (e.g., Berntsen, 1998, Berntsen and Hall, 2004, Schlagman and Kvavilashvili, 2008 and Schlagman et al., 2007). The lack of research on triggers is surprising given that Klinger, 1999 and Klinger, 2013 influential current concerns theory has consistently emphasised the importance of cues in eliciting mind-wandering. According to this theory, people’s goals and current concerns sensitize them towards relevant external or internal cues which, upon encountering, automatically re-activate the goal related material in one’s consciousness (Klinger, 1978 and Klinger et al., 1980). A recent laboratory study by McVay and Kane (2013) tested this assumption by using an on-going vigilance task with verbal cues some of which were based on the pre-screened ‘current concerns’ of participants. Collecting periodic thought probes shortly after the appearance of personally relevant cues, McVay and Kane (2013) found a 3–4% increase in mind-wandering relative to controls who were exposed to cue words with no personal relevance. Whilst a small difference, this offers preliminary evidence of the importance of environmental cues in mind-wandering, and their potential link to unfinished goals and underlines the need for further investigation in this particular area. Discrepant findings have started to emerge also in relation to the temporal focus of task unrelated thoughts. Within mind-wandering research, there is increasing evidence in support of the idea that when participants report experiencing task unrelated thoughts during the ongoing laboratory tasks, they tend to indicate that their thoughts are more often about the future rather than past events (Baird et al., 2011, Smallwood et al., 2011 and Stawarczyk et al., 2011). However, evidence from naturalistic studies is mixed, with two recent experience-sampling studies reporting the prospective bias (Poerio et al., 2013 and Song and Wang, 2012) but an earlier study by Klinger and Cox (1987) failing to find any differences between the frequency of thoughts about the past and future. Moreover, in a diary study by Finnbogadóttir and Berntsen (2013) where participants recorded their involuntary thoughts about the past (i.e., memories) and the future during two separate 1-day periods, the number of recorded IAMs (M = 22.61) did not differ from the number of recorded future thoughts (M = 21.50) (see also Berntsen & Jacobsen, 2008). Finally, different results have been obtained in relation to the effects of mood and depression on task unrelated thoughts and IAMs. Within mind-wandering research, several studies have reported a positive relationship between frequency of mind-wandering and measures of negative mood and dysphoria (Murphy et al., 2013, Smallwood et al., 2005, Smallwood et al., 2004 and Smallwood et al., 2007, Experiment 1; Smallwood, Davies, et al., 2004, Experiment 3). In addition, Smallwood and O’Connor (2011) showed that the induction of negative mood increased participants’ tendency to mind-wander about their past rather than future. These findings suggest that people with dysphoria and depression should experience higher frequency of IAMs than non-depressed controls. However, two studies on IAMs addressing this issue resulted in non-significant results. In a diary study by Watson, Berntsen, Kuyken, and Watkins (2013) clinically depressed and non-depressed participants had to record 10 IAMs (with a maximum of 2 IAMs per day to reduce the burden). Results showed that depressed participants took significantly longer (on average 30 days) to record 10 memories than non-depressed participants (14 days). This indicates that depressed groups did not experience IAMs more frequently than the non-depressed group although the possibility that they were less motivated to keep a diary could not be excluded. However, Kvavilashvili and Schlagman (2011) elicited IAMs under more controlled conditions using a laboratory method, developed by Schlagman and Kvavilashvili (2008), and found that participants with stable dysphoria (with the mean of 23.76 on Beck’s Depression Inventory, range 16–42) did not report experiencing more frequent IAMs than non-dysphoric participants (with the mean depression score of 2.46, range 0–6). These discrepant findings could be due to some important phenomenological differences between task unrelated thoughts studied within mind-wandering literature and research on IAMs. This, however, is unlikely given the universal agreement that some task unrelated thoughts reported by participants in mind-wandering experiments may refer to one’s autobiographical past, reflected in the instructions and examples of IAMs given to participants in these experiments (e.g., Smallwood et al., 2003 and Smallwood et al., 2011). An alternative and more plausible explanation for inconsistent findings emerging from the two separate literatures on mind-wandering and IAMs is the different methods used to study these phenomena. Indeed, the majority of research on mind-wandering is conducted in the laboratory, and participants are engaged in monotonous tasks and are intermittently stopped to report either the content of their thoughts at that moment, which will then be coded as task related or unrelated by researchers (e.g., Baird et al., 2011), or to categorise the thoughts as task related or unrelated without reporting the actual thought content (e.g., Smallwood, McSpadden, Luus, & Schooler, 2008). Originally, simple vigilance tasks with shapes as stimuli were used (e.g., green circle) and required that participants responded to infrequent targets (e.g., three red squares) with a simple button press (Giambra, 1995). More recently, several variants of this method have been used, some of which have relatively high levels of cognitive demand. For example, in the Sustained Attention to Response Task (SART) (Robertson, Manly, Andrade, Baddeley, & Yiend, 1997) which has been used in a large number of studies, participants respond continuously to non-target stimuli (mostly digits) by pressing a button, whilst withholding a response to an infrequent target (e.g., Jackson et al., 2013, McVay and Kane, 2009, McVay and Kane, 2013 and Smallwood et al., 2004). One reason why this task has become so popular is that it allows researchers to obtain behavioural indices of mind-wandering (e.g., errors of commission). Other ongoing tasks that have been used involve readings texts and encoding words (e.g., Reichle et al., 2010 and Smallwood et al., 2004). Very few studies have used more naturalistic methods such as thought sampling using paper and electronic diaries (Kane et al., 2007, Killingsworth and Gilbert, 2010, McVay et al., 2009, Poerio et al., 2013 and Song and Wang, 2012). In contrast, the vast majority of research on IAMs has been conducted using diary methods where participants are asked to keep a diary and record IAMs as and when they occur in everyday life (e.g., Berntsen, 1996 and Kvavilashvili and Mandler, 2004, Study 4; Mace, 2005). More recently, several lab methods have been developed to capture and measure IAMs under controlled conditions (Ball, 2007 and Mace, 2006). For example, Schlagman and Kvavilashvili (2008) developed a method which tries to simulate the conditions in which IAMs occur in everyday life (i.e., being engaged in an undemanding task and being surrounded by stimuli that can act as incidental triggers). To achieve this goal, participants are required to detect an infrequent target slide with vertical lines from hundreds of non-target slides with horizontal lines (each presented for 1.5 s). In addition to lines, participants can see cue words in the centre of each slide (e.g. ‘friendly boss,’ ‘missed opportunity,’ or ‘crossing the road’), which they are told are irrelevant to the vigilance task. Their task is to detect slides with vertical lines, and in addition, to stop the presentation by button press if at any point during the task they experience an involuntary memory from their past (self-caught method). Results from several studies show that, on average, participants report 6–7 memories during the 600–800 slide long presentations (range 0–30), and that the majority of recorded IAMs are reported to be triggered by irrelevant cue words presented on the slides (Kvavilashvili and Schlagman, 2011 and Schlagman and Kvavilashvili, 2008). Although there are some parallels between this task and simple vigilance or choice reaction tasks used in mind-wandering research, there are also clear differences, especially when compared to the SART. First, the number of targets is substantially lower (less than 1%) than in the tasks used in many mind-wandering studies (10–20%). This significantly reduces attentional demands of the ongoing task and induces relaxed state of mind, necessary for mind-wandering episodes. Second, and perhaps more important, it exposes participants to a steady stream of stimuli (positive, negative and neutral word phrases) that can trigger IAMs and possibly mind-wandering episodes in general (e.g., see McVay & Kane, 2013). Taken together, these important differences between the methods suggest that tasks used in mind-wandering research are perhaps using less optimal conditions for the occurrence of task unrelated thoughts than diary and laboratory methods used in the IAM research, and this could potentially explain the discrepant findings obtained in relation to triggers, temporal focus and effects of mood. 1.1. Present study To examine the role of these variables on the nature and frequency of task unrelated thoughts, the present study combined the mind-wandering and IAM paradigms by using a modified version of the method developed by Schlagman and Kvavilashvili (2008). Specifically, dysphoric and non-dysphoric participants were engaged in a vigilance task that involved detecting infrequent vertical lines and being exposed to irrelevant cue words in the centre of each slide. However, unlike the Schlagman and Kvavilashvili (2008) method, in which participants have to stop the presentation to report the occurrence of an IAM (self-caught method), in the present study a probe caught method was used in which participants were stopped 11 times throughout the task and had to record their thoughts at that moment (cf. Vannucci et al., 2014). In addition, unlike previous studies on mind-wandering, participants had to report any triggers for their thoughts. At the end of the task, they classified the reported thoughts as either past memories, current thoughts or thoughts about the future. Using this method, several important questions were addressed. The first question concerns the role of environmental cues in triggering off task thoughts. Although research on IAMs provides strong evidence for the importance of external cues in eliciting involuntary memories, the role of cues is less clear for task unrelated thoughts in mind-wandering with only two empirical studies that have directly addressed this question (McVay and Kane, 2013 and Song and Wang, 2012). Based on findings on IAMs, it was predicted that the majority of thought probes, classed as task unrelated, would be reported by participants as triggered by cue words presented on the screen during the vigilance task. An alternative prediction derived from the experience sampling study of Song and Wang (2012) is that the percentage of task-unrelated thoughts triggered by external cues would be smaller than reported in IAM studies. Furthermore, there has been no research on emotional valence of cues for task unrelated thoughts. Laboratory studies of IAMs have shown that IAMs are more likely to be elicited by negative than neutral or positive cues (Kvavilashvili and Schlagman, 2011 and Schlagman and Kvavilashvili, 2008). It is unclear, however, if this pattern extends to spontaneous task unrelated thoughts about the future or current situation. Based on diary studies of Berntsen and colleagues which showed that involuntary thoughts about the future were rated as more positive and idyllic than IAMs (Berntsen and Jacobsen, 2008 and Finnbogadóttir and Berntsen, 2013), it was predicted that thought probes classed as future thoughts would be more likely to be reported to have positive than neutral or negative cues. The second research question concerns the temporal focus of task unrelated thoughts. Although several laboratory studies of mind-wandering have found that participants report experiencing thoughts about future more often than thoughts about the past (Baird et al., 2011 and Smallwood et al., 2009, Experiment 1), this prospective bias has not been found under all conditions, particularly those in which participants were exposed to verbal information, i.e., when reading texts (Smallwood, Fitzgerald, Miles, & Phillips, 2009, Experiment 2). This raises an interesting possibility that people have a tendency to prospect in an environment that is devoid of meaningful cues (e.g., words), but when such cues are present, as in case of diary studies of Berntsen and Jacobsen (2008) and Finnbogadóttir and Berntsen (2013), and experience sampling study of Klinger and Cox (1987) then this prospective bias may disappear. Therefore, while laboratory research on mind-wandering would expect to obtain the standard prospective bias in the present study, the findings from Berntsen and colleagues and Smallwood, Fitzgerald, et al. (2009) suggest that participants will be reporting equal numbers of thoughts about past and future. The third research question concerns the frequency and nature of mind wandering in dysphoria. Existing findings from mind-wandering research suggest that in the present study dysphoric participants would report more task unrelated thoughts than non-dysphoric participants. In contrast, findings on depression and IAMs (Kvavilashvili and Schlagman, 2011 and Watson et al., 2013) suggest that there may be no differences between the two groups. One possible reason for higher rates of task unrelated thoughts reported by dysphoric participants in some studies on mind-wandering is that fairly demanding ongoing tasks have been used such as the SART and encoding words. Indeed, Smallwood, O’Connor, Sudbery, and Obonsawin (2007) demonstrated increased mind-wandering in dysphoria when participants had to encode words for future recall but not when they had to simply shadow the words. Given that in the present study, a very undemanding vigilance task was used, and that Kvavilashvili and Schlagman (2011) did not find any group differences in the number of reported IAMs, it was predicted that dysphoric and non-dysphoric participants would experience equal numbers of memories, and by extension, present and future thoughts. Two additional questions were addressed in relation to dysphoria. First, mood congruency effects were examined by comparing participants’ pleasantness ratings of their recorded thoughts. In line with findings of Kvavilashvili and Schlagman (2011) on IAMs, it was predicted that dysphoric participants would rate both their past memories and future thoughts more negatively than non-dysphoric participants. Second, very few studies have examined the actual content of task unrelated thoughts including thoughts about the future (Baird et al., 2011 and D’Argembeau et al., 2011). However, results of a diary study of D’Argembeau et al. (2011), in which participants had to record 10 thoughts about the future over a period of 5 days, showed that the majority of recorded thoughts (70%) were goal oriented and involved making decisions and planning upcoming tasks with only 11% of thoughts classed as thoughts or daydreams with no apparent purpose (e.g., fantasies, wishful thinking). In the present study, we wanted to replicate and extend this finding to dysphoric people by conducting a content analysis of future thoughts. Given depressed people’s tendency to engage in abstract rumination about the causes of their symptoms (Nolen-Hoeksema, Wisco, & Lyubomirsky, 2008), it is possible that in comparison to control group they would be more likely to engage in abstract, hypothetical thinking about the future (e.g., I wish I was financially more secure) than in planning upcoming tasks (I need to buy some ingredients for dinner on my way home this evening). Finally, we examined the specificity of recorded task unrelated thoughts. Although there is ample evidence for over general memory in depressed people who report repetitive rather than specific events when voluntarily recalling autobiographical memories, Kvavilashvili and Schlagman (2011) showed that this effect did not generalize to IAMs. In their study, dysphoric people’s IAMs were as specific as those of non-dysphoric participants (see also Watson et al., 2013). Therefore, in the present study we examined specificity ratings of thoughts to see if this finding could be extended to dysphoric people’s thoughts about the future as well.