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Spontaneously reported dreams and mind wandering in a naturalistic environment: An online questionnaire study
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Abstract
Spontaneous thoughts, such as dreaming and mind wandering, constitute a significant portion of human consciousness. Yet, the precise phenomenological and content-related similarities and differences between dreaming and waking mind wandering remain insufficiently understood. In this study, we address this gap by comparing 340 dreaming and mind wandering questionnaires that depending on the answers of participants ranged from 13 to 27 dimensions. While previous research primarily used laboratory settings and probe-caught methods, we adopted a naturalistic self-caught design to capture spontaneous experiences in daily life, which play a role in human cognition and well-being. Data was explored with a mixed-effect binary logistic regression models, which resulted in identifying dimensions that significantly predicted either dreaming or mind wandering and can therefore be considered as a dimension along which both states differ. In addition, the relative frequency distributions of all dimensions were used to illustrate similarities between dreaming and mind wandering. Finally, we compared a subgroup of dreaming and mind wandering containing visual imagery. Visual and immersive imagery and scene-organization are central features of dream phenomenology and at the centre of leading dream theories. To further investigate the immersive quality of dreaming and mind wandering, we considered features related to self-experience such as Feeling of Presence and Self-perspective. Overall results showed a complex picture of differences and similarities between dreaming and mind wandering that can inform future research about subtypes and help identify along which dimension dreaming might be considered as intensified compared to mind wandering
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Affective experiences occur across the wake-sleep cycle-from active wakefulness to resting wakefulness (i.e., mind-wandering) to sleep (i.e., dreaming). Yet, we know little about the dynamics of affect across these states. We compared the affective ratings of waking, mind-wandering, and dream episodes. Results showed that mind-wandering was more positively valenced than dreaming, and that both mind-wandering and dreaming were more negatively valenced than active wakefulness. We also compared participants' self-ratings of affect with external ratings of affect (i.e., analysis of affect in verbal reports). With self-ratings all episodes were predominated by positive affect. However, the affective valence of reports changed from positively valenced waking reports to affectively balanced mind-wandering reports to negatively valenced dream reports. These findings show that (1) the positivity bias characteristic to waking experiences decreases across the wake-sleep continuum, and (2) conclusions regarding affective experiences depend on whether self-ratings or verbal reports describing these experiences are analysed.
Humans spend a considerable portion of their lives engaged in ‘stimulus-independent thoughts' (SIT), or mental activity that occurs independently of input from the immediate external environment. Although such SITs are, by definition, different from thoughts that are driven by stimuli in one's external environment (i.e. stimulus-dependent thoughts; SDTs), at times, the phenomenology of these two types of thought appears to be deceptively similar. But how similar are they? We address this question by comparing the content of two types of SIT (dreaming and waking SITs) with the content of SDTs. In this 7 day, smartphone-based experience-sampling procedure, participants were intermittently probed during the day and night to indicate whether their current thoughts were stimulus dependent or stimulus independent. They then responded to content-based items indexing the qualitative aspects of their experience (e.g. My thoughts were jumping from topic to topic). Results indicate substantial distinctiveness between these three types of thought: significant differences between at least two of the three mental states were found across every measured variable. Implications are discussed.
This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.
Thoughts that appear to come to us ‘out of the blue’ or ‘out of nowhere’ are a familiar aspect of mental experience. Such thoughts tend to elicit feelings of surprise and spontaneity. Although we are beginning to understand the neural processes that underlie the arising of such thoughts, little is known about what accounts for their peculiar phenomenology. Here, we focus on one central aspect of this phenomenology—the experience of surprise at their occurrence, as it relates to internal probabilistic predictions regarding mental states. We introduce a distinction between two phenomenologically different types of transitions in thought content: (i) abrupt transitions , which occur at surprising times but lead to unsurprising thought content, and (ii) wayward transitions , which occur at surprising times and also lead to surprising thought content. We examine these two types of transitions using a novel approach that combines probabilistic and predictive processing concepts and principles. We employ two different probability metrics—transition and occurrence probability—to characterize and differentiate between abrupt and wayward transitions. We close by discussing some potentially beneficial ways in which these two kinds of transitions in thought content may contribute to mental function, and how they may be implemented at the neural level.
This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.
Whether we are awake or asleep is believed to mark a sharp divide between the types of conscious states we undergo in either behavioural state. Consciousness in sleep is often equated with dreaming and thought to be characteristically different from waking consciousness. Conversely, recent research shows that we spend a substantial amount of our waking lives mind wandering, or lost in spontaneous thoughts. Dreaming has been described as intensified mind wandering, suggesting that there is a continuum of spontaneous experience that reaches from waking into sleep. This challenges how we conceive of the behavioural states of sleep and wakefulness in relation to conscious states. I propose a conceptual framework that distinguishes different subtypes of spontaneous thoughts and experiences independently of their occurrence in sleep or waking. I apply this framework to selected findings from dream and mind-wandering research. I argue that to assess the relationship between spontaneous thoughts and experiences and the behavioural states of sleep and wakefulness, we need to look beyond dreams to consider kinds of sleep-related experience that qualify as dreamless. I conclude that if we consider the entire range of spontaneous thoughts and experiences, there appears to be variation in subtypes both within as well as across behavioural states. Whether we are sleeping or waking does not appear to strongly constrain which subtypes of spontaneous thoughts and experiences we undergo in those states. This challenges the conventional and coarse-grained distinction between sleep and waking and their putative relation to conscious states.
This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.
Hobson's AIM theory offers a general framework for thinking about states of consciousness like wakefulness, REM dreaming and NREM mentations in terms of a state space defined by the dimensions of the level of brain activity, the source of input, and the type of neurochemical modulation. This account inspired theoretical models of other altered states of consciousness—including hypnosis—claiming that studying REM dreaming can advance our understanding of these phenomena as well. However, recent developments showed that hypnosis is not a sleep like stage, and that the REM-centric attitude toward dreaming is mistaken. At the same time, the advancement of the neuro-cognitive theory claiming that dreaming and mind-wandering are on a continuum both underlain by default-mode network activity called many aspects of the AIM theory into question. Our aim in this paper is to show that certain hypnotic states—hypnotic dreams (experiences that subjects have in a hypnotic state as a result of an explicit suggestion to have a dream)—can, nevertheless, be highly relevant for the neuro-cognitive theory, and that their comparison with dreaming and mind-wandering has the potential to advance the field in unexpected ways.
Experience and thoughts that are unrelated to the external surroundings are pervasive features of human cognition. Research under the rubric of mind-wandering suggests that such internal experience is context-dependent, and that the content of ongoing thought differentially influences a range of associated outcomes. However, evidence on how the extent of mind-wandering and its content translate from the laboratory to daily life settings is scarce. Furthermore, the relationship between such patterns of thought with markers of stress in daily life remains underexplored. In the current study, we examined multiple aspects of mind-wandering of ninety-three healthy participants (47 women, 25.4 ± 3.9 years) in both the laboratory and daily life and explored two questions: (a) how are mind-wandering extent and content correlated across both settings, and (b) what are their relationships with subjective stress and salivary cortisol levels in daily life? Our results suggest that the extent of off-task thinking is not correlated across contexts, while features of content—i.e., social, future-directed and negative thought content—robustly translate. We also found that daily life subjective stress was linked to more on-task, negative, and future-directed thinking, suggesting stress was linked with the need to act on personally relevant goals. Based on these results we speculate that differences in the links between stress and ongoing thought in daily life may be one reason why patterns of thinking vary from lab to everyday life. More generally, these findings underline the need to consider both context and content in investigating mind-wandering and associated features of subjective experience, and call for caution in generalizing laboratory findings to participants’ daily lives.
Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized. Here we review the neuroscientific literature on lucid dreaming, including electroencephalographic, neuroimaging, brain lesion, pharmacological and brain stimulation studies. Electroencephalographic studies of lucid dreaming are mostly underpowered and show mixed results. Neuroimaging data is scant but preliminary results suggest that prefrontal and parietal regions are involved in lucid dreaming. A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams. Finally, we discuss strategies to measure lucid dreaming, including best-practice procedures for the sleep laboratory. Lucid dreaming has clinical and scientific applications, and shows emerging potential as a methodology in the cognitive neuroscience of consciousness. Further research with larger sample sizes and refined methodology is needed.
Throughout history, there have been reports and claims that consideration of dreams can produce personal realizations and insight. We assessed Exploration–Insight scores associated with discussing REM and non-REM dreams in connection with recent waking life experiences. Thirty-one participants were cued in the sleep laboratory for a daydream report and then awakened from REM and N2 sleep for dream reports. Participants subsequently discussed each of their dream and daydream reports for 30–40 min with two experimenters, following the structured Ullman (1996) dream group discussion procedure. Participants assessed the benefit of discussing the reports by completing the Gains from (Day)Dream Interpretation (G[D]DI) questionnaire. We found no difference in G(D)DI scores between discussing REM and N2 dream reports, and no difference between dream and daydream discussions in engagement and thoroughness of exploring the reports. However, discussing dream reports produced higher scores on the G(D)DI Exploration–Insight subscale compared with discussing daydream reports. Significant differences were evident in items reflecting the learning of what the report means in terms of waking life issues. Frontal theta prior to waking from N2 was significantly associated with Exploration–Insight score obtained after N2 dream discussion, but this relationship was not found for REM dreams. The findings of high ratings of Exploration–Insight after discussing dreams were evident even though participants did not select the dream, unlike what can occur for home recorded dreams, and even though discussion was brief. We suggest that insight might be produced by embodied and metaphorical thinking in dreams.
Recent claims that people spend 30–50% of their waking lives mind wandering (Killingsworth & Gilbert, 2010; Kane et al., 2007) have become widely accepted and frequently cited. While acknowledging attention to be inconstant and wavering, and mind wandering to be ubiquitous, we argue and present evidence that such simple quantitative estimates are misleading and potentially meaningless without serious qualification. Mind-wandering estimates requiring dichotomous judgments of inner experience rely on questionable assumptions about how such judgments are made, and the resulting data do not permit straightforward interpretation. We present evidence that estimates of daily-life mind wandering vary dramatically depending on the response options provided. Offering participants a range of options in estimating task engagement yielded variable mind-wandering estimates, from approximately 60% to 10%, depending on assumptions made about how observers make introspective judgments about their mind-wandering experiences and how they understand what it means to be on- or off-task.
This chapter offers a functional account of why the mind- when free from the demands of a task or the constraints of heightened emotions- tends to wander from one topic to another, in a ceaseless and seemingly random fashion. We propose the default variability hypothesis, which builds on William James's phenomenological account of thought as a form of mental locomotion, as well as on recent advances in cognitive neuroscience and computational modeling. Specifically, the default variability hypothesis proposes that the default mode of mental content production yields the frequent arising of new mental states that have heightened variability of content over time. This heightened variability in the default mode of mental content production may be an adaptive mechanism that (1) enhances episodic memory efficiency through de- correlating individual episodic memories from one another via temporally spaced reactivations, and (2) facilitates semantic knowledge optimization by providing optimal conditions for interleaved learning.
Dreams are sometimes described as an intensified form of spontaneous waking thought. Lucid dreams may seem to be a counterexample, because metacognitive insight into the fact that one is now dreaming is often associated with the ability to deliberately control the ongoing dream. This chapter uses conceptual considerations and empirical research findings to argue that lucid dreaming is in fact a promising and rich target for the future investigation of spontaneous thought. In particular, the investigation of dream lucidity can shed light on the relationship between metacognitive insight and control, on the one hand, and the spontaneous, largely imagistic cognitive processes that underlie the formation of dream imagery, on the other hand. In some cases, even lucid insight itself can be described as the outcome of spontaneous processes, rather than as resulting from conscious and deliberate reasoning. This raises new questions about the relationship
between metacognitive awareness and spontaneous thought.
The continuity hypothesis (1) posits that there is continuity, of some form, between waking and dreaming mentation. A recent body of work has provided convincing evidence for different aspects of continuity, for instance that some salient experiences from waking life seem to feature in dreams over others, with a particular role for emotional arousal as accompanying these experiences, both during waking and while asleep. However, discontinuities have been somewhat dismissed as being either a product of activation-synthesis, an error within the consciousness binding process during sleep, a methodological anomaly, or simply as yet unexplained. This paper presents an overview of discontinuity within dreaming and waking cognition, arguing that disruptions of consciousness are as common a feature of waking cognition as of dreaming cognition, and that processes of sleep-dependent memory consolidation of autobiographical experiences can in part account for some of the discontinuities of sleeping cognition in a functional way. By drawing upon evidence of the incorporation, fragmentation, and reorganization of memories within dreams, this paper proposes a model of discontinuity whereby the fragmentation of autobiographical and episodic memories during sleep, as part of the consolidation process, render salient aspects of those memories subsequently available for retrieval in isolation from their contextual features. As such discontinuity of consciousness in sleep is functional and normal.
The tendency for the mind to wander to concerns other than the task in hand is a fundamental feature of human cognition, yet the consequence of variations in its experiential content for psychological functioning are not well understood. Here, we adopted a multivariate pattern analysis approach, simultaneously decomposing experience sampling data with neural functional connectivity data, revealing dimensions that simultaneously describe individual variation in self-reported experience and default mode network connectivity. We identified dimensions corresponding to traits of positive, habitual thoughts and spontaneous task-unrelated thoughts. These dimensions were uniquely related to aspects of cognition, such as executive control and the ability to generate information in a creative fashion, and independently distinguished well-being measures. These data provide the most convincing evidence to date that the mind-wandering state encompasses a broad range of different experiences and that this heterogeneity underlies its complex relationship to psychological functioning.
Thoughts occur during wake as well as during dreaming sleep. Using experience sampling combined with high-density EEG, we investigated the phenomenal qualities and neural correlates of spontaneously occurring thoughts across wakefulness, non-rapid eye movement (NREM) sleep, and REM sleep. Across all states, thoughts were associated with activation of a region of the midcingulate cortex. Thoughts during wakefulness additionally involved a medial prefrontal region, which was associated with metacognitive thoughts during wake. Phenomenologically, waking thoughts had more metacognitive content than thoughts during both NREM and REM sleep, whereas thoughts during REM sleep had a more social content. Together, these results point to a core neural substrate for thoughts, regardless of behavioral state, within the midcingulate cortex, and suggest that medial prefrontal regions may contribute to metacognitive content in waking thoughts.
Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep.
Mind-wandering and daydreams (i.e., spontaneous thoughts that are both task-unrelated and decoupled from current sensory perceptions) have recently become the object of increased interest in cognitive psychology and neuroscience. To date, however, there have been relatively few attempts at investigating the form and content of these thoughts, and what individuals are exactly thinking about when they daydream or their minds wander from the here and now. In this chapter, I will first provide an historical overview of the studies that investigated the phenomenological properties of mind-wandering and daydreams. In a second section, I will review the current state of research examining how specific phenomenological features of these thoughts are related to beneficial and deleterious aspects of cognitive and affective functioning. I will conclude by discussing possible avenues for future investigations, such as how the content and context of occurrence of mind-wandering and daydreams might interact to
The idea that dreaming is a simulation of the waking world is currently becoming a far more widely shared and accepted view among dream researchers. Several philosophers, psychologists, and neuroscientists have recently characterized dreaming in terms of virtual reality, immersive spatiotemporal simulation, or realistic and useful world simulation. Thus, the conception of dreaming as a simulated world now unifies definitions of the basic nature of dreaming within dream and consciousness research. This novel concept of dreaming has consequently led to the idea that social interactions in dreams, known to be a universal and abundant feature of human dream content, can best be characterized as a simulation of human social reality, simulating the social skills, bonds, interactions, and networks that we engage in during our waking lives. Yet this tempting idea has never before been formulated into a clear and empirically testable theory of dreaming. Here we show that a testable Social Simulation Theory (SST) of dreaming can be formulated, from which empirical predictions can be derived. Some of the predictions can gain initial support by relying on already existing data in the literature, but many more remain to be tested by further research. We argue that the SST should be tested by directly contrasting its predictions with the major competing theories on the nature and function of dreaming, such as the Continuity Hypothesis (CH) and the Threat Simulation Theory (TST). These three major theories of dreaming make differing predictions as to the quality and the quantity of social simulations in dreams. We will outline the first steps towards a theory-and-hypothesis-driven research program in dream research that treats dreaming as a simulated world in general and as a social simulation in particular. By following this research program it will be possible to find out whether dreaming is a relatively unselective and thus probably non-functional simulation of the waking world (CH), a simulation primarily specialized in the simulation of dangerous and threatening events that present important challenges for our survival and prosperity (TST), or whether it is a simulation primarily specialized in training the social skills and bonds most important for us humans as a social species (SST). Whatever the evidence for or against the specific theories turn out to be, in any case the conception of dreaming as a simulated world has already proved to be a fruitful theoretical approach to understanding the nature of dreaming and consciousness.
Most research on mind-wandering has characterized it as a mental state with contents that are task unrelated or stimulus independent. However, the dynamics of mind-wandering - how mental states change over time - have remained largely neglected. Here, we introduce a dynamic framework for understanding mind-wandering and its relationship to the recruitment of large-scale brain networks. We propose that mind-wandering is best understood as a member of a family of spontaneous-thought phenomena that also includes creative thought and dreaming. This dynamic framework can shed new light on mental disorders that are marked by alterations in spontaneous thought, including depression, anxiety and attention deficit hyperactivity disorder.
Dreaming can be explained as the product of an interaction among memory processes, elaborative processes, and phenomenal awareness. A feedback circuit is activated by this interaction according to the associative links and the requirements of the dream scene. Recently, it has been hypothesized that a partial similarity exists between dreaming and mind wandering and that these two processes may involve the same neural default network. This commentary discusses the differences and similarities between phenomenal consciousness during dreaming and phenomenal consciousness during mind wandering from the perspective of the “continuity” of engagement of cognitive systems. The greatest difference consists in the lack of reality testing during dreaming. Dream imagery is hallucinatory by nature. Consequently, the simulated world in dreams makes dream imagery more akin to perception. In contrast, the imagery of mind wandering is more similar to imagination. The level of meta-awareness is preserved more frequently and to a greater degree in mind wandering.
Nightmares (NMs) are characterized by intense negative emotion. Research suggests that frequent NM sufferers also have greater inclinations to fantasy and dream-like daydreams, although it is not known whether they experience intense negative emotion as part of these waking state cognitions. We assessed the daydreams and nap dreams of NM participants to determine whether they have more negative daydream content and more vivid imagery overall. NM and control (CTL) participants completed a daydream procedure followed by a nap targeted to contain 80 min total sleep time and an awakening 10 min into rapid eye movement (REM) sleep. For both daydreams and nap dreams, participants completed a questionnaire regarding 4 factors: negativity, positivity, body sensation, and bizarreness. Results revealed the NM group had elevated positivity, body sensation and bizarreness ratings for daydreams compared with the CTL group, but did not differ from them for negativity ratings. NM participants also had elevated body sensation ratings for nap dreams, but did not differ for negativity, positivity, or bizarreness. Thus, while NMs themselves are characterized by negative affect, NM sufferers nonetheless have higher than normal positivity, body sensation, and bizarreness in their daydreams and specifically more body sensation in their laboratory nap dreams. This may reflect some change in the affective structure of imagery among NM sufferers (e.g., altered experiences of bodily arousal), the differential influence of circadian factors on the 2 groups, or the fact that sleeping in the laboratory tends to suppress NMs.
Recent research suggests that sleepiness and mind-wandering—the experience of thoughts that are both stimulus-independent and task-unrelated—frequently co-occur and are both associated with poorer cognitive functioning. Whether these two phenomena have distinguishable effects on task performance remains unknown, however. To investigate this question, we used the online experience sampling of mind-wandering episodes and subjective sleepiness during a laboratory task (the Sustained Attention to Response Task; SART), and also assessed mind-wandering frequency and sleep-related disturbances in daily life using self-report questionnaires. The results revealed that the tendency to experience mind-wandering episodes during the SART and daily life was associated with higher levels of daytime sleepiness and sleep-related disturbances. More important, however, mind-wandering and sleepiness were independent predictors of SART performance at both the within- and between-individuals levels. These findings demonstrate that, although mind-wandering and sleepiness frequently co-occur, these two phenomena have distinguishable and additive effects on task performance.
The present review gives an overview on common theories of dreaming with a specific emphasis on how
they are able to explain lucid dreaming. The theories are grouped either to such that describe structural or biological processes of dreams or to such that describe evolutionary and adaptive functions of dreams. This overview shows that none of the theories outlined is fully capable of explaining neither non-lucid dreaming nor lucid dreaming. With respect to the first group, the concept of “protoconsciousness” is the theory that at best explains lucid dreaming. With respect to theories with an evolutionary and adaptive function of dreams, those theories, that stress the problem solving or simulation functions of dreams are more suited to explain lucid dreaming. Further, aspects that induce or amplify lucidity and the neural mechanisms that may be involved in lucid dreaming are described.
In this paper we argue that autobiographical memory (AM) activity across sleep and wake can provide insight into the nature of dreaming, and vice versa. Activated memories within the sleeping brain reflect one’s personal life history (autobiography). They can appear in largely fragmentary forms and differ from conventional manifestations of episodic memory. Autobiographical memories in dreams can be sampled from non-REM as well as REM periods, which contain fewer episodic references and become more bizarre across the night. Salient fragmented memory features are activated in sleep and re-bound with fragments not necessarily emerging from the same memory, thus de-contextualizing those memories and manifesting as experiences that differ from waking conceptions. The constructive nature of autobiographical recall further encourages synthesis of these hyper-associated images into an episode via recalling and reporting dreams. We use a model of AM to account for the activation of memories in dreams as a reflection of sleep-dependent memory consolidation processes. We focus in particular on the hyperassociative nature of AM during sleep.
Conscious experience is fluid; it rarely remains on one topic for an extended period without deviation. Its dynamic nature is illustrated by the experience of mind wandering, in which attention switches from a current task to unrelated thoughts and feelings. Studies exploring the phenomenology of mind wandering highlight the importance of its content and relation to meta-cognition in determining its functional outcomes. Examination of the information-processing demands of the mind-wandering state suggests that it involves perceptual decoupling to escape the constraints of the moment, its content arises from episodic and affective processes, and its regulation relies on executive control. Mind wandering also involves a complex balance of costs and benefits: Its association with various kinds of error underlines its cost, whereas its relationship to creativity and future planning suggest its potential value. Although essential to the stream of consciousness, various strategies may minimize the downsides of mind wandering while maintaining its productive aspects. Expected final online publication date for the Annual Review of Psychology Volume 66 is November 30, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
A core aspect of human cognition involves overcoming the constraints of the present environment by mentally simulating another time, place, or perspective. Although these self-generated processes confer many benefits, they can come at an important cost, and this cost is greater for some individuals than for others. Here we explore the possibility that the costs and benefits of self-generated thought depend, in part, upon its phenomenological content. To test these hypotheses, we first developed a novel thought sampling paradigm in which a large sample of young adults recalled several recurring thoughts and rated each thought on multiple content variables (i.e., valence, specificity, self-relevance, etc.). Next, we examined multi-level relationships among these content variables and used a hierarchical clustering approach to partition self-generated thought into distinct dimensions. Finally, we investigated whether these content dimensions predicted individual differences in the costs and benefits of the experience, assessed with questionnaires measuring emotional health and wellbeing. Individuals who characterized their thoughts as more negative and more personally significant scored higher on constructs associated with Depression and Trait Negative Affect, whereas those who characterized their thoughts as less specific scored higher on constructs linked to Rumination. In contrast, individuals who characterized their thoughts as more positive, less personally significant, and more specific scored higher on constructs linked to improved wellbeing (Mindfulness). Collectively, these findings suggest that the content of people’s inner thoughts can (1) be productively examined, (2) be distilled into several major dimensions, and (3) account for a large portion of variability in their functional outcomes.
The waking mind is often occupied with mental contents that are minimally constrained by events in the here and now. These self-generated thoughts-e.g., mind-wandering or daydreaming-interfere with external task performance and can be a marker for unhappiness and even psychiatric problems. They also occupy our thoughts for upwards of half of the time, and under non-demanding conditions they (i) allow us to connect our past and future selves together, (ii) help us make successful long-term plans and (iii) can provide a source of creative inspiration. The lengths that the mind goes to self-generate thought, coupled with its apparent functionality, suggest that the mind places a higher priority on such cognition than on many other mental acts. Although mind-wandering may be unpleasant for the individual who experiences it and disruptive to the tasks of the moment, self-generated thought allows consciousness freedom from the here and now and so reflects a key evolutionary adaptation for the mind. Here we synthesize recent literature from cognitive and clinical psychology and propose two formal hypotheses that (1) highlight task context and thought content as critical factors that constrain the costs and benefits of self-generated thought and (2) provide direction on ways to investigate the costs and benefits from an impartial perspective.
Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both “daydreaming” and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous functional neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an “intensified” version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.
Two approaches to measuring dreaming and waking cognition were compared. Forty-three subjects wrote detailed descriptions of a dreaming and a waking experience and also used a questionnaire to evaluate the presence of particular types of cognition and metacognition in the target experience. Later, independent judges rated the subjects’ narrative reports for the incidence of the same types of cognition and meta cognition. A lower incidence of some types of cognition was observed when assessment was based on judges’ ratings of the narrative reports than when subjects themselves assessed the incidence of these events. However, the basic relationship between dreaming and waking cognition was consistent for both measurement approaches. Subjects’ and judges’ evaluations of dreaming and waking experiences did not differ for internal commentary, sudden attention, focused attention, public self-consciousness, emotion, self-reflection, and thwarted intentions, although both subjects and judges attributed choice to waking experiences more often than to dreaming experiences. The value of using converging measures to compare dreaming and waking cognition is discussed, as well as whether dreaming cognition is best conceptualized as continuous or discontinuous with waking cognition.
After completing a short form of the Boundary Questionnaire, 17 students with high scores indicative of thin boundaries and 13 students with low scores indicative of thick boundaries participated in a testing session in which they reported their most recent dream, their most recent daydream, an outstanding dream, and an outstanding daydream. Dreams and daydreams were rated on 3 8-point scales (bizarreness, dreamlikeness, emotionality) by 2 independent raters who were blind to Boundary Questionnaire scores. The dream reports were rated significantly more bizarre, more dreamlike, and more emotional than the daydream reports. In addition, the thin boundaried Ss' reports were significantly more bizarre than the thick boundaried Ss' reports. Indeed, the recent daydreams of Ss with thin boundaries were as bizarre as the recent dreams of those with thick boundaries. Test-retest reliability for the Boundary Questionnaire using data from 90 students in general psychology classes was satisfactory. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Evidence suggests continuity between cognition in waking and sleeping states. However, one type of cognition that may differ is episodic thoughts of the past and future. The current study investigated this across waking, NREM sleep and REM sleep. We analyzed thought reports obtained from a large sample of individuals (N = 138) who underwent experience-sampling during wakefulness as well as serial awakenings in sleep. Our data suggest that while episodic thoughts are common during waking spontaneous thought, episodic thoughts of both the past and the future rarely occur in either N2 or REM sleep. Moreover, replicating previous findings, episodic thoughts during wakefulness exhibit a strong prospective bias and frequently involve autobiographical planning. Together, these results suggest that the occurrence of spontaneous episodic thoughts differs substantially across waking and dreaming sleep states. We suggest that this points to a difference in the way that human consciousness is typically experienced across the sleep-wake cycle.
Previous research suggests that patterns of ongoing thought are heterogeneous, varying across situations and individuals. The current study investigated the influence of multiple tasks and affective style on ongoing patterns of thought. We used 9 different tasks and measured ongoing thought using multidimensional experience sampling. A Principal Component Analysis of the experience sampling data revealed four patterns of ongoing thought: episodic social cognition, unpleasant intrusive, concentration and self focus. Linear Mixed Modelling was used to conduct a series of exploratory analyses aimed at examining contextual distributions of these thought patterns. We found that different task contexts reliably evoke different thought patterns. Moreover, intrusive and negative thought pattern expression were influenced by individual affective style (depression level). The data establish the influence of task context and intrinsic features on ongoing thought, highlighting the importance of documenting how thought patterns emerge in cognitive tasks with different requirements.
Significance
Our minds rarely stay still when left alone. Such trains of thought, however, may unfold in vastly different ways. Here, we combined electrophysiological recording with thought sampling to assess four types of thoughts: task-unrelated, freely moving, deliberately constrained, and automatically constrained. Parietal P3 was larger for task-related relative to task-unrelated thoughts, whereas frontal P3 was increased for deliberately constrained compared with unconstrained thoughts. Enhanced frontal alpha power was observed during freely moving thoughts compared with non-freely moving thoughts. Alpha-power variability was increased for task-unrelated, freely moving, and unconstrained thoughts. Our findings indicate these thought types have distinct electrophysiological signatures, suggesting that they capture the heterogeneity of our ongoing thoughts.
Recent research has indicated that reducing the difficulty of a task by increasing the predictability of critical stimuli produces increases in intentional mind wandering, but, contrary to theoretical expectations, decreases in unintentional mind wandering. Here, we sought to determine whether reducing task difficulty by reducing working-memory load would yield similar results. Participants completed an easy (Choice Response Time; CRT) task and a relatively difficult (Working Memory; WM) task, and intermittently responded to thought probes asking about intentional and unintentional mind wandering. As in prior studies, we found higher rates of intentional mind wandering during the easy compared to the more difficult task. However, we also found more unintentional mind wandering during the difficult compared to the easy task. We discuss these results in the context of theoretical accounts of mind wandering.
Mind wandering is frequently defined as task-unrelated or perceptually decoupled thought. However, these definitions may not capture the dynamic features of a wandering mind, such as its tendency to 'move freely'. Here we test the relationship between three theoretically dissociable dimensions of thought: freedom of movement in thought, task-relatedness, and perceptual decoupling (i.e., lack of awareness of surroundings). Using everyday life experience sampling, thought probes were randomly delivered to participants' phones for ten days. Results revealed weak intra-individual correlations between freedom of movement in thought and task-unrelatedness, as well as perceptual decoupling. Within our dataset, over 40% of thoughts would have been misclassified under the assumption that off-task thought is inherently freely moving. Overall, freedom of movement appears to be an independent dimension of thought that is not captured by the two most common measures of mind wandering. Future work focusing on the dynamics of thought may be crucial for improving our understanding of the wandering mind.
Dreams are descirbed as "single-minded," meaning that they tend to be unaccompanied by other, simultaneous streams of thought and imagery. Four manifestations of single-mindedness are discussed: (1) the absence of a reflective awareness that one is dreaming while the dream is in progress; (2) the absence of alternative images and thoughts while attending to the primary dream content; (3) the tendency for dream content to stay on a single thematic track; (4) the absence of a set to remember the dream while it is in progress. This isolation of dream content, from other thought systems is then considered as but one manifestation of a more generalized relative isolation of dream content, which includes isolation from presleep stimuli, contemporaneous stimuli, organismic state, and autonomic and motor activity. Some of the implications of dream isolation for dream psychophysiology and theories of dreaming are outlined.
Consciousness is often said to disappear in deep, dreamless sleep. We argue that this assumption is oversimplified. Unless dreamless sleep is defined as unconscious from the outset there are good empirical and theoretical reasons for saying that a range of different types of sleep experience, some of which are distinct from dreaming, can occur in all stages of sleep. We introduce a novel taxonomy for describing different kinds of dreamless sleep experiences and suggest research methods for their investigation. Future studies should focus on three areas: memory consolidation, sleep disorders, and sleep state (mis)perception. Our proposal suggests new directions for sleep and dream science, as well as for the neuroscience of consciousness, and can also inform the diagnosis and treatment of sleep disorders.
The past decade has seen a surge of research examining mind-wandering, but most of this research has not considered the potential importance of distinguishing between intentional and unintentional mind-wandering. However, a recent series of papers have demonstrated that mind-wandering reported in empirical investigations frequently occurs with and without intention, and, more crucially, that intentional and unintentional mind-wandering are dissociable. This emerging literature suggests that, to increase clarity in the literature, there is a need to reconsider the bulk of the mind-wandering literature with an eye toward deconvolving these two different cognitive experiences. In this review we highlight recent trends in investigations of the intentionality of mind-wandering , and we outline a novel theoretical framework regarding the mechanisms underlying intentional and unintentional mind-wandering.
The task of differentiating dreaming from other forms of imaginative cognition and of classifying different dream types and subtypes is largely incomplete. However, a growing interest in dreaming’s capacity for simulating waking reality experience offers a viable point of departure for furthering this unfinished task. Most types of dream content measures (e.g., prevalence, frequency, intensity, structural coherence) are predicated, directly or indirectly, on this assumption about dreaming’s capacity for simulating reality and provide converging support for the reality-simulation assumption. Even measures of dream bizarreness—which is quite common in dreams—may be understood as attempts to quantify failures of the simulation mechanism. Both simulated content and bizarreness measures may be viable approaches for completing the task of dream classification. However, a third level of analysis also related to reality simulation may prove key in this enterprise. This is the simulation of the subtle, perception like nature of waking experience, namely, the process of seeking out and picking up apparent information, not the appreciation of the contents of this process. This level of subjective experience is only difficultly accessed by awaking, self reflective subjects, so its study in dream experience may require greater use of targeted probe questions and less conventional methods such as selecting subjects for their communication abilities and training them in self-observation.
Content analysis is one of the basic methods used in psychological dream research. Whereas reliability issues have been addressed in the literature quite often, the validity of dream content analysis has rarely been studied in a systematic way. The present study investigated the validity of a bizarreness scale by asking whether an external judge estimates the number of bizarre elements per dream in the same way as the dreamer herself or himself. As reported previously for dream emotions, a marked underestimation of bizarreness by the external judges was found. The findings indicate, therefore, that written dream reports do not yield not a complete picture of the original dream experience and hence the validity of dream content analysis which is based on written dream reports is limited at least in several areas. How severely the validity problem affects the results of content analytic studies and which dream characteristics are most susceptible to this kind of error should be investigated in future studies using a methodology similar to that employed in the present study.
Evidence of reflective awareness and metacognitive monitoring during REM sleep dreaming poses a significant challenge to the commonly held view of dream cognition as necessarily deficient relative to waking cognition. To date, dream metacognition has not received the theoretical or experimental attention it deserves. As a result, discussions of dream cognition have been underrepresented in theoretical accounts of consciousness. This paper argues for using a converging measures approach to investigate the range and limits of cognition and metacognition across the sleep–wakefulness cycle. The paradigm developed by LaBerge and his colleagues to study "lucid-control" dreaming offers one such framework for relating phenomenological, cognitive, and physiological measures. In a lucid-control dream, the dreamer is both aware that the experimental context is a dream (lucidity) and has the ability to intentionally regulate aspects of the dream (control). Subjects can make patterns of deliberate eye movements to signal from the dream and thus index significant events such as the time of lucidity onset and the completion of previously agreed-upon tasks in the dream. Lucid dreaming and other examples of reflective awareness during dreaming have important implications for models of human cognition. The existence of these phenomena raises fundamental questions about current assumptions regarding "state" constraints on consciousness and cognition (i.e., the notion that dreaming involves exclusively nonconscious processing while waking involves conscious processing).
Bizarreness is a cognitive feature common to REM sleep dreams, which can be easily measured. Because bizarreness is highly specific to dreaming, we propose that it is most likely brought about by changes in neuronal activity that are specific to REM sleep. At the level of the dream plot, bizarreness can be defined as either discontinuity or incongruity. In addition, the dreamer's thoughts about the plot may be logically deficient.
We propose that dream bizarreness is the cognitive concomitant of two kinds of changes in neuronal dynamics during REM sleep. One is the disinhibition of forebrain networks caused by the withdrawal of the modulatory influences of norepinephrine (NE) and serotonin (5HT) in REM sleep, secondary to cessation of firing of locus coeruleus and dorsal raphe neurons. This aminergic demodulation can be mathematically modeled as a shift toward increased error at the outputs from neural networks, and these errors might be represented cognitively as incongruities and/or discontinuities.
We also consider the possibility that discontinuities are the cognitive concomitant of sudden bifurcations or “jumps” in the responses of forebrain neuronal networks. These bifurcations are caused by phasic discharge of pontogeniculooccipital (PGO) neurons during REM sleep, providing a source of cholinergic modulation to the forebrain which could evoke unpredictable network responses. When phasic PGO activity stops, the resultant activity in the brain may be wholly unrelated to patterns of activity dominant before such phasic stimulation began. Mathematically such sudden shifts from one pattern of activity to a second, unrelated one is called a bifurcation. We propose that the neuronal bifurcations brought about by PGO activity might be represented cognitively as bizarre discontinuities of dream plot.
We regard these proposals as preliminary attempts to model the relationship between dream cognition and REM sleep neurophysiology. This neurophysiological model of dream bizarreness may also prove useful in understanding the contributions of REM sleep to the developmental and experiential plasticity of the cerebral cortex.
29 undergraduates carrying a beeper for 7 days described properties of their consciousness on a total of 1,425 occasions by means of a thought-sampling questionnaire, anxiety and depression measures, and activity report forms. Intra-S analyses of thought variables identified 8 orthogonal factors: Visual Modality, Auditory Modality, Operantness, Attentiveness to External Stimulation, Controllability, Strangeness, Past Time Orientation, and Future Time Orientation. Most thought samples contained some interior monologue largely independent of other variables. The visual modality predominated for most individuals. Approximately one-third of thought was predominantly undirected, one-third was stimulus-independent, and about one-quarter contained at least traces of dream-like elements. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The question of consciousness is perhaps the most significant problem still unsolved by science. In
Inner Presence, Antti Revonsuo proposes a novel approach to the study of consciousness that integrates findings from philosophy, psychology, and cognitive neuroscience into a coherent theoretical framework. Arguing that any fruitful scientific approach to the problem must consider both the subjective psychological reality of consciousness and the objective neurobiological reality, Revonsuo proposes that the best strategy for discovering the connection between these two realities is one of "biological realism," using tools of the empirical biological sciences. This approach, which he calls the "biological research program," provides a theoretical and philosophical foundation that contemporary study of consciousness lacks. Revonsuo coins the term "world simulation metaphor" and uses this metaphor to develop a powerful way of thinking about consciousness as a biological system in the brain. This leads him to propose that the dreaming brain and visual consciousness are ideal model systems for empirical consciousness research. He offers a comprehensive overview and critical analysis of consciousness research and defends his approach against currently popular philosophical views, in particular against approaches that deny or externalize phenomenal consciousness, or claim that brain activity is not sufficient for consciousness. He systematically examines the principal issues in the science of consciousness--the contents of consciousness, the unity of consciousness and the binding problem, the explanatory gap and the neural correlates of consciousness, and the causal powers and function of consciousness. In
Inner Presence, Revonsuo draws together empirical data from a wide variety of sources, including dream research, brain imaging, neuropsychology, and evolutionary psychology, into the theoretical framework of the biological research program, thus pointing the way toward a unified science of consciousness. Applying imaginative thought experiments,
Inner Presence reaches beyond the current state of the art, revealing how the problem of consciousness may eventually be solved by future science. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In this paper, we address the different ways in which dream research can contribute to interdisciplinary consciousness research. As a second global state of consciousness aside from wakefulness, dreaming is an important contrast condition for theories of waking consciousness. However, programmatic suggestions for integrating dreaming into broader theories of consciousness, for instance by regarding dreams as a model system of standard or pathological wake states, have not yielded straightforward results. We review existing proposals for using dreaming as a model system, taking into account concerns about the concept of modeling and the adequacy and practical feasibility of dreaming as a model system. We conclude that existing modeling approaches are premature and rely on controversial background assumptions. Instead, we suggest that contrastive analysis of dreaming and wakefulness presents a more promising strategy for integrating dreaming into a broader research context and solving many of the problems involved in the modeling approach.