Reading minds: expanding the toolkit for studying spontaneous thoughts

A very common and characteristic experience in the human mental life is the propensity to disengage from the external environment, including an ongoing task, into focusing internally, to our own thoughts. This has been termed mind wandering and is now a fast-growing area of research across disciplines such as philosophy, psychology and neuroscience. However, as a relatively new area of research, with much of its growing starting only two decades ago, there is still a lot of scientific work to be done in the area, including on finding the most scientifically sound ways to manipulate and measure those episodes. This is more critical for science because of the private nature of the phenomenon, which has been widely forcing researchers to resort on either subjective reports of mind wandering, which heavy reliance on introspection and meta-awareness can pose reliability and validity issues, or a combination of subjective reports with some objective markers of on- or off-task focus, which despite being a enormous step to objectively determine the state of mind wandering, does not help in terms of predicting or decoding the contents of thoughts. Investigating the contents of thoughts is of prime importance because most of the detriments (and benefits) of mind wandering have been linked to particular categories of thoughts. Therefore, the aim of this thesis is to add to the currently available set of objective tools for studying the contents of mind wandering by establishing neuroimaging and electrophysiological measures to help decode and predict the contents of thoughts. Because of the heterogeneity of the phenomenon, I do this buy focusing on specific dimensions of thoughts, drawing from the well-established literature on external attention all the way to considering some of the reviewed phenomenological accounts of mind wandering. It has been shown that people engage in mind wandering episodes either deliberately or spontaneously. In this thesis, when referring to mind wandering, we focused on the latter, and on associated categories of thoughts that are irrelevant to and away from the task, involuntary, repetitive, and sometimes personally or motivationally relevant.

In Study 1 (Chapter 2), I address the research gap on mechanisms of internal attentional capture by own thoughts, as opposed to well-studied external mechanisms, by using perceptual reactivations of a specific ‘planted’ thought about a person, to track a specific thought in the brain, in order to ‘see’ the occurrence of an involuntary and intrusive thought. For this I resorted on both univariate and multivariate fMRI approaches and looked into the Fusiform Face Area. I also used connectivity analysis to investigate the parallels between external and internal attentional capture, finding common parietal regions implicated. Then, my Study 2 (Chapter 3) is both a behavioural and an electrophysiology study in which I establish the phenomenological characteristics of the executive and affective dimensions of thoughts and resort on a combination of EEG and facial EMG to establish the objective neural and muscular markers of executive and affective thoughts. On Study 3 (Chapter 4) I quantify and characterise the extent and nature of the impact of the COVID-19 pandemic on task focus, and the role of negative affect. The research presented throughout this thesis has methodological implications, and also implications on mental and educational settings, which are discussed on the General Discussion (Chapter 5).