Comparing the phenomenological qualities of stimulus-independent thought, stimulus-dependent thought and dreams using experience sampling

Abstract

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’.

The Dynamics of Affect Across the Wake-Sleep Cycle: From Waking Mind-Wandering to Night-Time Dreaming

“…These findings are in line with previous studies that have compared SR of affect experienced during mind-wandering and dream episodes (Carr et al, 2016;Carr & Nielsen, 2015;Gross et al, 2021) but stand in contrast to a study that compared ER of affect in mind-wandering and night-time dream reports (Perogamvros et al, 2017). However, it is important to note that in the latter study, the authors only analysed so-called high-thought mind-wandering and dream reports, which may explain differences in the results.…”

“…All this may have led to more similarity between wakefulness and mind-wandering than would have otherwise been the case. However, given that our results corroborate those of Gross et al (2021), who used experience sampling and differentiated stimulus-dependent thoughts (active wakefulness) and stimulus-independent thoughts (mindwandering), gives credence to our findings and indicates that the positivity bias applies to active wakefulness as well as to intentional and spontaneous mind-wandering. Nevertheless, it would be important to compare the affective quality of different forms and aspects of mindwandering with that of dreaming.…”

“…In a recent study, Gross et al (2021) used an experience-sampling method to compare the content of waking thoughts, or what the authors called stimulus-dependent thoughts, with two types of stimulus-independent thoughts-those occurring during waking mind-wandering and night-time dreaming. Participants were signalled several times during the day and night.…”

“…The latter is likely due to the large variation in methods used for obtaining and analysing data. Importantly, only one study (Gross et al, 2021) has systematically compared the affective quality of waking mind-wandering and night-time dreaming in the same participants outside the laboratory environment. However, in that study the focus was on (stimulus-independent) thoughts in the narrower sense, rather than subjective experiences more broadly.…”

Offline perception: an introduction

“…Although similarities and differences have been reported at the phenomenological level as well, no research has yet rigorously compared the core phenomenological features of dreaming and mindwandering. In the eleventh paper of the issue, Gross et al [64] address this problem extending the comparison to the phenomenological features of stimulus-dependent online experiences as well.…”