Manuela Kirberg

This special issue unites original theoretical and empirical research on two topics that are gaining traction in cognitive neuroscience and psychology, but so far have small philosophical footprints: dreaming and waking mind wandering. While the fields of dream and mind wandering research are largely separate, phenomenological and neurophysiological similarities between waking mind wandering and sleep-related experiences suggest that these phenomena are intimately connected. Together, they raise important questions about the nature and functions of spontaneous mental phenomena and their relation to wakefulness and sleep, as well as for theories of attention, action, and consciousness.

Until recently, mental imagery has largely been regarded as an exclusively conscious phenomenon. However, recent empirical results suggest that mental imagery can also occur unconsciously. People who report having no experiences of mental imagery often perform similar to controls on behavioural tasks thought to require imagery. A surprising number of them also display significant levels of imagery-based priming, and recent neural decoding studies have shown that imagery-related information is being processed in their visual cortex. However, investigating unconscious imagery empirically is not straightforward. One challenge is to establish that imagery is genuinely unconscious as opposed to merely going unreported due to response biases. Another is to clarify how imagistic and indirect perceptual processing needs to be to qualify as imagery. In this paper, we take a closer look at the evidence for unconscious imagery, argue that it is not as compelling as it initially appears, and outline a strategy for advancing research on this question.

Spontaneous thoughts and experiences, such as dreaming and mind wandering, form a significant part of our conscious mental lives. 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 questionnaire responses 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 used a self-caught design to capture spontaneous experiences in daily life. Data were explored with 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 differences between both states. 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 and help identify along which dimension dreaming might be considered as intensified compared to mind wandering.

This paper aims to contribute to an integrated understanding of what goes missing in adverse meditation experiences and in cases of depersonalization disorder. Depersonalization disorder is characterized by distressing alterations in, and sometimes the complete disappearance of, the 'I'-sense. This paper examines the nature of the 'I'-sense and what it means to lose it from a Buddhist perspective. We argue for a nihilist position that the loss of the sense of self arises from misidentifications of the psychophysical complex with non-self elements, such as memories, thoughts, or body movements. Drawing from meditation experiences and depersonalization symptoms, we propose that the sense of self is not a static entity given in experience but fluctuates between various senses of self (and no-self) depending on circumstances. This pluralistic understanding of the various senses of self offers a more nuanced understanding of symptoms in depersonalization disorder and adverse effects of meditation practices.

Although we are beginning to understand the neurocognitive processes that underlie the emergence of dreaming, what accounts for the bizarre phenomenology of dreams remains debated. I address this question by comparing dreaming with waking mind wandering and challenging previous accounts that utilize bizarreness to mark a sharp divide between conscious experiences in waking and sleeping. Instead, I propose that bizarreness is a common, non-deficient feature of spontaneous offline simulations occurring across the sleep-wake cycle and can be tied to the specific characteristics of spontaneous thought as being dynamic, unconstrained, (hyper)associative and highly variable in content. Rather than misrepresenting waking reality, bizarreness can be employed to investigate the very building blocks of spontaneous cognition. The absence of bizarreness in thought processes is imposed by automatic and deliberate cognitive constraints. By contrast, thought and memory processes operating on their own without such constraints are inherently marked by different degrees and types of bizarreness.