Introduction
Disproportionately negative future-oriented cognition is implicated in the aetiology and maintenance of emotional disturbance within cognitive models of depression (Abramson, Metalsky, & Alloy,
1989; Beck,
1976; Beck, Brown, Steer, Eidelson, & Riskind,
1987). Empirical evidence has shown that, when asked to deliberately evaluate or anticipate future events, individuals with depression exhibit pessimistic judgments of their personal futures (Alloy & Ahrens,
1987; MacLeod et al.,
2005; Miranda & Mennin,
2007), and show impaired ability to anticipate positive relative to negative future events (Holmes, Lang, Moulds, & Steele,
2008; MacLeod & Conway,
2007; MacLeod & Salaminiou,
2001; Morina, Deeprose, Pusowski, Schmid, & Holmes,
2011). However, research suggests that the emotional consequences of mental representations of future events are greater when such representations occur spontaneously, without instruction or intention, relative to when such representations were generated deliberately (Cole, Staugaard, & Berntsen,
2016). Further, experience sampling research suggests that the emotional consequences of future-oriented mental representations appear to be restricted to those involving mental imagery (Barsics, Van der Linden, & D’Argembeau,
2016). As such, understanding biases in the tendency to spontaneously engage in mental imagery-based emotional future thinking may further illuminate the link between future-oriented cognition and emotional disturbance in depression.
Mental imagery can evoke emotional response in an as-if-real manner
Consciously experienced mental representations can occur in mental imagery format, or verbal-linguistic format (Paivio,
1990). Mental imagery refers to internal representations of sensory-perceptual information in the absence of external sensory input, often referred to as “‘seeing from the mind’s eye’, ‘hearing from the mind’s ear’, and so on” (Kosslyn, Ganis, & Thompson,
2001, p. 635). Due to the recruitment of common neural substrates during mental imagery and sensory perception (Cichy, Heinzle, & Haynes,
2012; Klein et al.,
2004; Kosslyn,
1994; Pearson & Kosslyn,
2015), mental imagery has the capacity to simulate not only the perceptual details of hypothetical events, but also the experiential correlates of such experiences in an as-if-real manner (Lang,
1979; Moulton & Kosslyn,
2011). Research has demonstrated the capacity for imagery representations of emotion stimuli to evoke emotional response at subjective, physiological, and neural levels (see Ji, Heyes, MacLeod, & Holmes,
2016). In healthy individuals, many studies have demonstrated that when asked to deliberately engage in mental imagery representations relative to verbal-linguistic representations of negative and positive information, imagery representations tend to evoke greater emotional response, at least at subjective levels (Holmes, Lang, & Shah,
2009; Holmes & Mathews,
2005; Holmes, Mathews, Mackintosh, & Dalgleish,
2008; Mathews, Ridgeway, & Holmes,
2013; Nelis, Vanbrabant, Holmes, & Raes,
2012).
Maladaptive cognition implicated in emotional disorders often involves mental imagery, although the focus has been on anxiety related disorders (Holmes & Mathews,
2010). Seminal theories of depression refer to both “thoughts and visual images” (p. 8) as relevant factors in the aetiology and treatment of depression (Beck, Rush, Shaw, & Emergy,
1979). More recently, a large questionnaire-based study investigating the properties of depressive thoughts found that more than half of 403 depressed patients reported their depressive thoughts to involve auditory and visual mental imagery (Moritz et al.,
2014), suggesting that cognition involving mental imagery may be a prevalent feature of maladaptive cognition in depression too. Given the capacity for mental imagery to strongly impact emotional experience, investigating depression-linked biases in the tendency to experience mental representations involving mental imagery (whether consisting of imagery only, or a combination of imagery and verbal thought) is of particular importance for understanding the cognitive basis of such emotional psychopathology.
Spontaneous future imagery-evoked emotional response
More recently, experience sampling research assessing the real-time occurrence of future-oriented thoughts and emotional states throughout the day has shown that individuals are more likely to experience negative or positive thoughts about the future following experiences of negative or positive emotional states, respectively (Barsics et al.,
2016). In turn, the occurrence of such negative or positive thoughts about the future are associated with increases in subsequent experiences of negative and positive emotional states, indicating a bi-directional relationship between future-oriented cognition and state emotion (Barsics et al.,
2016). An important aspect of Barsics et al.’s finding is that this relationship was restricted to emotional future-oriented cognition involving mental imagery, as the occurrence of emotional future cognition not involving mental imagery (i.e. verbal-linguistic thought) was not related to subsequent emotional states. As such, higher levels of negative, or indeed depressed, mood may arise, and be maintained by, a disproportionate tendency to spontaneously engage in negative relative to positive future thinking, particularly if such thinking involves mental imagery.
Biases in mental imagery-based future thinking in depression
Abnormalities in mental imagery-based cognition have been implicated in depression, indicating elevated accessibility of imagery-based mental representations and reduced accessibility of positive imagery-based mental representations (Holmes, Blackwell, Burnett Heyes, Renner, & Raes,
2016). For example, when asked to deliberately anticipate negative and positive events in one’s personal future, individuals with higher depression symptoms are able to anticipate more negative future experiences and fewer positive future experiences than those with lower depression symptoms (MacLeod & Byrne,
1996; MacLeod & Salaminiou,
2001; for a review see MacLeod,
2016). When asked to deliberately generate imagery representations of future events in response to cues, higher depression symptoms are associated with reduced specificity of future events, particularly in response to positive cues (Hallford, Austin, Takano, & Raes,
2018), and reduced imagery vividness for positive relative to negative events (Holmes, et al.,
2008; Morina et al.,
2011; Szőllősi, Pajkossy, & Racsmány,
2015).
Reduced ability to deliberately generate imagery-based positive relative to negative representations of the future could potentially explain why individuals with higher depression symptoms have a reduced positive mood and elevated negative mood. However, depression-linked individual differences in the relative ability to generate positive and negative future imageries in response to direct instruction may not necessarily align with depression-linked individual differences in the relative tendency to do so without such instructions. Laboratory research in healthy individuals has shown that the emotional impact of spontaneously generated mental imagery representations of future events is greater relative to deliberately generated mental imagery representations of future events (Cole et al.,
2016). Therefore, investigating depression-linked biases in the tendency to engage in emotional future imagery may further illuminate the role of future thinking and emotional disturbance in depression.
Limited understanding of spontaneous mental imagery-based future thinking in depression
Compared to research on the ability to generate future imagery in depression when deliberately instructed to generate such imagery (deliberate generation), research on depression-linked tendency to generate future imagery when not instructed to do so (spontaneous generation) is relatively neglected. In community samples, higher levels of depression symptoms appear to be related to higher frequency of self-reported daily experiences of negative mental imagery, and less frequent experiences of positive imagery (Weßlau, Cloos, Höfling, & Steil,
2015). Patients with depression report frequently experiencing unwanted mental imagery in the form of spontaneously occurring emotionally distressing mental imagery of past and future experiences (Brewin, Gregory, Lipton, & Burgess,
2010; Moritz et al.,
2014; Patel et al.,
2007). However, these and other studies have tended to rely on retrospective estimations of the frequency of distressing mental imagery (Newby & Moulds,
2011; Patel et al.,
2007; Reynolds & Brewin,
1998). Given that naturally occurring thoughts tend to be rapidly forgotten if their occurrence is not recorded immediately (Berntsen,
1996), such as in a thought diary or via a button press during a computer task, interpretation of retrospective reports of thought frequency is thus constrained. In contrast, assessing the frequency of cognition as it occurs in real time has the potential to provide a more accurate assessment of naturally occurring thought frequency.
Few laboratory studies have assessed depression-linked individual differences in spontaneous mental imagery-based future thinking frequency in real time. Previous research has shown that spontaneous thoughts tended to occur during states of diffused attention when the individual felt bored, tired, or unengaged with the task at hand (Berntsen,
1996; Kosslyn, Seger, Pani, Hillger, and Stephen,
1990; McVay & Kane,
2010). Therefore, laboratory studies designed to induce states of diffused attention are suitable for measuring task unrelated thought frequency, such as low-demand sustained attention to response tasks involving go/no-go tasks (Robertson, Manly, Andrade, Baddeley, & Yiend,
1997). In addition, previous research has shown that spontaneous cognition is often triggered by external cues (Kvavilashvili & Mandler,
2004; Plimpton, Patel, & Kvavilashvili,
2015). Therefore, exposing participants to standardised environmental cues is more appropriate for investigating depression-linked individual differences in spontaneous cognition frequency than experience sampling studies ‘in-the-wild’, particularly as depression symptoms are likely to influence the selection of environmental context in daily life.
Kvavilashvili and colleagues (Kvavilashvili & Schlagman,
2011; Schlagman & Kvavilashvili,
2008) developed a variant of the sustained attentional vigilance tasks that additionally exposed participants to visually presented verbal cues. Using this approach, studies have found no significant relationship between depression symptom level and the general frequency of future-oriented task unrelated thoughts (TUTs) (Hoffmann, Banzhaf, Kanske, Bermpohl, & Singer,
2016; Plimpton et al.,
2015), although Hoffmann et al. (
2016) found future-oriented TUTs to be more emotionally negative in depressed relative to non-depressed individuals. However, such studies did not examine the frequency of future-oriented TUTs as a function of their emotional valence. It is therefore unclear whether dysphoria level is related to the tendency to spontaneously generate more negative relative to positive future TUTs.
Most importantly, no study investigating depression-linked individual differences in spontaneous future thinking has addressed whether (and to what extent) these vary with representational format, i.e. emotional future representations that involve mental imagery versus those that do not. In addition, imagining hypothetical future experiences (episodic simulation) recruits the core neural networks supporting episodic memory of past experiences, involving the flexible recombination of relevant contextual and sensory features from past experiences (Addis, Wong, & Schacter,
2007; Schacter, Addis, & Buckner,
2007,
2008). Therefore, it would be important to understand whether any relationship observed between depression symptom level and the tendency to experience mental imagery-based emotional future TUTs are unique to future-oriented TUTs by examining the relationship between depression symptom level and the tendency to experience mental imagery-based emotional past TUTs. If the same pattern of relationship was found between depression symptom level and both past- and future-oriented TUTs, then effects are likely to reflect depression-linked biases in the tendency to engage in emotional mental time travel in general, rather than a bias specific to the tendency to imagine emotional futures.
The present study
The present laboratory study aims to investigate individual differences in the tendency to engage in spontaneous mental imagery-based emotional future thinking in participants varying in the level of self-reported symptoms of dysphoria (as indicated by depression questionnaire scores).
Examining depression-linked individual differences in thought frequency requires a task that is capable of evoking sufficient variation in the occurrence of TUTs. While most previous studies have used intermittent and infrequent random thought probes to assess TUT occurrence, the limitation with the probe-caught sampling approach is the fixed and low number of data points obtainable during brief laboratory tasks (typically 15–20 min). This “probe-caught” method is able to capture only a fraction of actual task unrelated thoughts, and such an approach may not yield sufficient variability in valid data points for examining the presence of systematic relationships between an individuals’ emotional states and the occurrence of particular types of cognition (e.g. future-oriented emotional task unrelated thoughts involving mental imagery). In contrast, self-reporting occurrences of mindwandering have the potential capacity to capture a greater proportion of the occurrences of task unrelated cognition, increasing the chance of obtaining sufficient data points for group-level frequency comparisons of cognition by valence and mode using means or rank order analysis. As such, following previous research (Cole et al.,
2016), the present study employed a “self-caught” method, where participants self-reported TUTs as they occurred.
A novel task unrelated thinking (TUT) task was developed based on the Sustained Attention to Response Task (SART) by Robertson, Manly, Andrade, Baddeley, & Yiend (
1997). The standard SART is a go/no-go task, which involves the withholding of key presses to rare targets (one in nine trials being a no-go trial). The SART measures lapses in sustained attention as a result of shifts from controlled to automatic processing (Robertson et al.,
1997), and is widely used in mindwandering research (Christoff, Gordon, Smallwood, Smith, & Schooler,
2009; Smallwood, Beach, & Schooler,
2008). Previous research has shown that the same task with a high target frequency (one in two) induces less mindwandering relative to the standard low target frequency version (one in nine) in both low and high dysphoria samples (Murphy, Macpherson, Manly, & Dunn,
2013). The present study therefore utilised the standard low target frequency SART to encourage mindwandering and the emergence of task unrelated thoughts.
Further, the SART was modified to include exposure to standardised external cues in the form of emotional and non-emotional words presented during the SART task. This novel variant of the SART is similar to another vigilance task involving the presentation of verbal cues, developed by Schlagman & Kvavilashvili (
2008) and used in studies such as Plimpton et al. (
2015). However, the present TUT task differs to that of Schlagman & Kvavilashvili (
2008)’s cued TUT approach in two key aspects. First, while Schlagman & Kvavilashvili (
2008) visually presented verbal cues in the centre of the screen on every trial and participants were instructed to ignore the cues as they were task irrelevant, this invariably introduced visual attentional competition with the main task (discriminating the identity of visually presented line patterns), thereby making the task more difficult and less monotonous. In addition, participants were asked to indicate during the task whether each TUT reported was related to a visually presented verbal cue, which invariably reduces the task irrelevance of cues and increases awareness of cues during the task. The present task therefore used aurally presented verbal cues and participants were not required to indicate whether their TUTs were related to cues. Participants reported the occurrence of self-caught TUTs in real time during a number digit vigilance task while simultaneously exposed to task contexts that were emotional (negative and positive verbal cues) and unemotional (neutral verbal cues). To rule out the contribution of additional depression-linked factors that could affect TUT frequency, such as task difficulty or cue processing, the relationship between dysphoria level and task performance (errors of commission) and cue recognition memory were assessed.
Hypotheses
The study tested the hypothesis that higher levels of dysphoria would be associated with greater tendency to spontaneously engage in negative relative to positive mental imagery-based future thinking. Spontaneous cognition is defined as TUTs generated without instructions to generate cognition of any particular kind.
The study further aimed to explore whether any observed relationship between dysphoria level and the tendency to generate emotional imagery future-TUTs was (a) specific to emotionally toned imagery future-TUTs (emotional specificity); (b) specific to imagery-based emotional future TUTs (representational format specificity); and (c) specific to future-oriented imagery TUTs (temporal orientation specificity). To verify (a) emotional specificity, the relationship between depression scores and neutral imagery future-TUT frequency will be assessed; to verify (b) representational format specificity, the relationship between depression scores and emotional future-oriented non-imagery TUTs will be assessed; and to verify (c) temporal orientation specificity, the relationship between depression score and emotional past-oriented imagery TUTs will be assessed. Given previous research on depression-linked reduction in positive relative to negative future imagery vividness when such imagery was deliberately generated, the present study also explored the vividness of spontaneously generated future imagery.
Discussion
The present study investigated the presence of depression-linked bias in the tendency to engage in spontaneous mental imagery-based future thinking. As hypothesized, results showed that when not instructed to deliberately generate task unrelated cognition of any kind, higher depression scores were associated with lower positive bias in the frequency of imagery-based emotional future-oriented task unrelated thoughts (TUTs). This depression-linked reduction in positive future imagery bias was driven by an increasing tendency to generate negative future imagery, and a decreasing tendency to generate positive future imagery. While the positive relationship between BDI-II score and the proportional frequency of positive future imagery approached statistical significance, the magnitude of the relationship (
rs = − 0.28) can be considered of moderate effect size in individual difference research (Gignac & Szodorai,
2016). Importantly, no relationship was observed between depression scores and the frequency of emotionally neutral future imagery, indicating the observed depression-linked effect was specific to emotional future imagery. In addition, depression scores were not related to future-oriented TUTs that did not involve mental imagery (verbal-linguistic representation only), indicating that the observed depression-linked bias was specific to imagery-based future cognition. Finally, depression scores were not related to the frequency of imagery-based past-oriented TUTs, indicating that the observed bias was specific to future imagery.
Implications
Results from the study indicate that when engaging in off-task mindwandering, individuals with higher levels of symptoms of depression may be more likely to experience negative relative to positive mental imagery representations of the future than those with lower levels of depression symptoms. What might this mean in daily life? Previous experience sampling research suggests that up to half of waking mental life may consist of thoughts unrelated to the task at hand that occur spontaneously, without explicit purpose or intention (Killingsworth & Gilbert,
2010; McVay, Kane, & Kwapil,
2009). The same pattern has been found in a diary study examining naturally occurring mental imagery-based cognition (Kosslyn, Seger, Pani, & Hillger,
1990). As such, given the capacity for mental imagery to evoke emotional response (Ji et al.,
2016), a greater tendency to experience task unrelated negative relative to positive future imagery is likely to contribute to elevated negative emotional states and reduced positive emotional states, thereby contributing to emotional disturbance in depression.
The present research extends previous literature on future thinking in depression by providing empirical evidence that the depression-linked biases observed when participants were instructed to deliberately think of emotional future events (Holmes et al.,
2016; MacLeod,
2016), which are also observed when participants are not instructed to deliberately generate task unrelated cognition of any kind. The present findings are consistent with theoretical accounts that implicate maladaptive spontaneous cognition in depression vulnerability, in part due to the potential of such thoughts to promote feelings of hopelessness and pessimistic beliefs about the future (Marchetti, Koster, Klinger, & Alloy,
2016; Miloyan, Pachana, & Suddendorf,
2014). Importantly, results from the present study suggest that it may be specifically the tendency to generate imagery-based mental representations of the future that is specifically implicated in depression. The findings also corroborate previous retrospective self-report studies that indicate impoverished experiences of positive relative to negative future imagery in depression (Weßlau & Steil,
2014) and dysphoria (Weßlau et al.,
2015) in daily life. If future studies using clinical samples replicate the present findings, this would indicate that depression is associated with a reduction in the general likelihood of experiencing positive relative to negative mental representations of the future involving mental imagery.
Furthermore, the present study also extends research on spontaneous past-oriented cognition by examining the role of mental representational format. It is somewhat surprising that the present study did not find any relationship between spontaneous past-oriented mental imagery and dysphoria level, given previous findings concerning past-oriented spontaneous cognition using similar sustained attention to response tasks. Such studies have found a greater tendency in past-oriented task unrelated thinking to be associated with depressed mood (Smallwood & O’Connor,
2011; Smallwood, O’Connor, Sudbery, & Obonsawin,
2007) and depression (Hoffmann et al.,
2016). However, it is worth noting that such studies did not employ the use of cues to trigger TUTs. Research comparing SART tasks with concurrent verbal cues, relative to the same task without concurrent verbal cues, found that verbal cues increased the frequency of past-oriented TUTs and decreased the frequency of future-oriented TUTs, but did not modulate the frequency of present-oriented or atemporal TUTs (Vannucci, Pelagatti, & Marchetti,
2017). Previous research employing verbal cues has found that past-oriented TUTs occurred more frequently than future-oriented TUTs overall, but the tendency to spontaneously experience past-oriented TUTs was not modulated by dysphoria (Plimpton et al.,
2015). Although Plimpton et al. (
2015) did not delineate the nature of past-oriented TUTs based on their representational format, consistent with their findings, post-hoc exploratory analysis of the present data indicated no significant relationship between BDI-II scores and the frequency of past-oriented TUTs overall (
rs = − 0.19,
p = 0.21).
It is also worth noting that the present study found no relationship between dysphoria level and the frequency of negative or positive TUTs not involving mental imagery (all
rs < |0.11|, all
p > 0.63). This may at first appear surprising given that depression is associated with rumination, a predominantly verbal-linguistic form of internally generated passive thinking mode focused on the causes and negative consequences of one’s problems and depressive symptoms (Nolen-Hoeksema,
1991). However, more recent research indicate that sensory-perceptual representations are also highly prevalent in depressive cognition (Moritz et al.,
2014), with more recent measures of repetitive negative thinking (including rumination) assessing the frequency of both thoughts (verbal-linguistic) and images (McEvoy, Hayes, Hasking, & Rees,
2017; Watkins, Moulds, & Mackintosh,
2005). As such, it is possible that depression-linked biases in past-oriented spontaneous cognition are more readily observable at clinical levels of depression, but such thoughts are likely to involve both imagery and verbal-linguistic representations. Of course, given that TUTs that did not involve any mental imagery comprised only 36% of total TUTs, it is possible that floor effects in the frequency of such TUTs make possible relationships difficult to detect. For example, it is possible that the exclusive use of auditory cues preferentially promoted the natural occurrence of mental imagery-based cognition, relative to purely verbal-linguistic cognition due to modality-specific task load that disproportionately taxes the phonological loop component of working memory (Repovs & Baddeley,
2006). Future studies could test this possibility by comparing two versions of the present task, one presenting auditory cues, and one presenting visual cues.
Limitations
A possible limitation of the task is that self-reporting of task unrelated thinking may have influenced the natural occurrence of such thinking compared to probe-caught approaches. Both self- and probe-caught approaches prime participants’ awareness of off-task thinking, and while self-caught mindwandering relies on participants’ monitoring of their own conscious experience (Giambra,
1993; Schooler,
2002), previous research suggests that it does not alter phenomenological experience during undemanding cognitive tasks (Schooler,
2002; Smallwood, Baracaia, Lowe, & Obonsawin,
2003). However, previous research employing both self-caught as well as probe-caught mindwandering found thought probes caught additional TUTs not self-reported by participants (Schooler,
2002), indicating that studies using only self-caught TUT reporting may still underestimate the true occurrence of TUTs. In addition, even with the employment of cues and a “self-caught” approach to assessing TUT occurrence, frequencies of future-oriented TUTs were still low when analysed as a function of emotional valence and representational format. Future studies investigating individual differences in spontaneous cognition frequency may benefit from employing both self-caught and probe-caught approaches, and/or to seek to specifically evoke higher future focus during the task, such as priming current concerns.
In addition, the present results should be interpreted with caution as the study had a relatively small sample size, particularly due to the loss of three participants for the main analysis (with even fewer participants in some analyses due to the lack of TUTs reported that are of the category under examination), and four participants for the cue recognition memory task, leading to reduced power to detect true effects. Further validation of the present results using larger samples will be required to assess the reliability of the present results.
Further, it is likely that both the self-caught and probe-caught approaches to assess task unrelated thinking impacts on the natural flow of task unrelated thinking by requiring participants to report on the occurrence of task unrelated thinking. The present results therefore must be interpreted within the context of a controlled laboratory environment designed to encourage the occurrence of off-task thinking as well as reporting of its occurrence. Further, it must be acknowledged that asking participants to answer specific questions about the nature of task unrelated thinking (e.g. representational format, valence, and temporal orientation) may influence the general occurrence of task unrelated thinking. However, given that no emphasis was drawn to specific types of TUTs within each characteristic category (i.e. thoughts of a particular representational format, valence or temporal orientation), observed biases in the occurrence of TUTs within such characteristic categories are unlikely to be influenced by the need to report on the presence or nature of task unrelated thinking in general.
Finally, another limitation of the study is that the
spontaneous occurrence of TUTs was operationalised as those occurring without instructions to deliberately generate task unrelated cognition of any kind, but the extent to which such TUTs occurred with or without intention was not further assessed. Given recent research on the dissociation between unintentional and intentional mindwandering (Seli, Carriere, & Smilek,
2015; Seli, Risko, & Smilek,
2016), delineating between depression-linked differences in the tendency to intentionally versus unintentionally engage in emotional future thinking may provide further insight into nature of cognitive biases underlying depression.
Future directions
To further illuminate the role of biased tendency to spontaneously engage in emotional imagery-based future thinking, future research should replicate the present effects in clinical populations. In addition, while the present study used emotional words that were not selected to be of specific relevance to depression, previous research indicates that self-relevance of cues is associated with greater mood-congruent bias effects in depression (cf. Wisco,
2009). Therefore, future studies could test whether the use of depression-relevant emotional cues are associated with stronger outcomes, particularly in clinical populations. In addition, to advance the present line of research further, future research could investigate the degree to which the occurrence of spontaneous emotional imagery-based future thinking contributes to on-going emotional experience in depression, such as assessing state emotion change before, during, and after the TUTT task.
The present study showcases a novel laboratory paradigm for eliciting TUTs that can assess depression-linked individual differences in the tendency to experience future-oriented imagery. Such tasks can fruitfully be used within translational studies, such as emerging interventions that aim to tackle depression via training cognition to be more positive and less negative, such as future cognitive bias modification of interpretation (CBM-I) research (for a review, see Menne-Lothmann et al.
2014). Future CBM-I training studies could employ the present laboratory task as a measure of far transfer to assess the impact of interpretation bias training effects on the spontaneous tendency to experience positive relative to negative thoughts.
It would be important for future research to investigate the underlying causes of depression-linked biases in the tendency to imagine emotional experiences in the future, such as the role of negative interpretations of ambiguous information and negative expectations of the future. At the same time, future research should also examine the downstream impacts of biased tendency to engage in emotional imagery-based future thinking in dysphoria and depression. Using the same experimental paradigm, future studies could measure the degree to which variation in state emotions after the task are accounted for by the occurrence of negative and positive future imagery during the task. Further, given the growing theoretical focus and empirical evidence that imagery-based mental simulations of future events facilitate decision-making, planning and self-regulatory behaviour (Bulley, Henry, & Suddendorf,
2016; Gilbert & Wilson,
2007; Kappes & Morewedge,
2016; Seligman, Railton, Baumeister, & Sripada,
2013; Szpunar, Spreng, & Schacter,
2014; Taylor, Pham, Rivkin, & Armor,
1998), future research should examine how biases in imagery-based future thinking impact decision-making, planning and self-regulation in depression.