Olivia Carter

In contentless experience there is an absence of mental content such as thought, perception, and mental imagery. The path to contentless experience in meditation can be taken to comprise the meditation technique, and the experiences on the way to the contentless “goal-state/s”. Shamatha, Transcendental, and Stillness Meditation are each said to access contentless experience, but the path to that experience in each practice is not yet well understood from a scientific perspective. We have employed evidence synthesis to select and review 135 expert texts from those traditions. In this paper we describe the techniques and interim-states based on the expert texts and compare them across the practices on key dimensions. Superficially, Shamatha and Transcendental Meditation appear very different to Stillness Meditation in that they require bringing awareness to a meditation object. The more detailed and systematic approach taken in this paper indicates that posturally Shamatha is closer to Stillness Meditation, and that on several other dimensions Shamatha is quite different to both other practices. In particular, Shamatha involves greater measures to cultivate attentional stability and vividness with respect to an object, greater focusing, less tolerance of mind-wandering, more monitoring, and more deliberate doing/control. Achieving contentless experience in Shamatha is much slower, more difficult, and less frequent. The findings have important implications for taxonomies of meditation and for consciousness, neuroscientific, and clinical research/practice, and will provide new and useful insights for meditation practitioners.

Contentless experience involves an absence of mental content such as thought, perception, and mental imagery. In academic work it has been classically treated as including states like those aimed for in Shamatha, Transcendental, and Stillness Meditation. We have used evidence synthesis to select and review 135 expert texts from within the three traditions. In this paper we identify the features of contentless experience referred to in the expert texts and determine whether the experiences are the same or different across the practices with respect to each feature. We identify 65 features reported or implied in one or more practices, with most being reported or implied in all three. While there are broad similarities in the experiences across the traditions, we find that there are differences with respect to four features and possibly many others. The main difference identified is that Shamatha involves substantially greater attentional stability and vividness. Another key finding is that numerous forms of content are present in the experiences, including wakefulness, naturalness, calm, bliss/joy, and freedom. The findings indicate that meditation experiences described as contentless in the academic literature can in fact involve considerable variation, and that in many and perhaps most cases these experiences are not truly contentless. This challenges classical understandings in academic research that in these so-called contentless experiences all content is absent, and that the experiences are therefore an identical state of _pure consciousness_ or consciousness itself. Our assessment is that it remains an open question whether the experiences aimed for in the three practices should be classed as pure consciousness. Implications of our analysis for neuroscientific and clinical studies and for basic understandings of the practices are discussed.

Shamatha, Transcendental, and Stillness Meditation are said to aim for “contentless” experiences, where mental content such as thoughts, perceptions, and mental images is absent. Silence is understood to be a central feature of those experiences. The main source of information about the experiences is texts by experts from within the three traditions. Previous research has tended not to use an explicit scientific method for selecting and reviewing expert texts on meditation. We have identified evidence synthesis as a robust and transparent method that is suitable for this purpose. In this paper we use evidence synthesis based on expert texts to examine silence/quietness as a feature of the contentless experiences in the three practices. Objective criteria were used to select a sample of 135 expert texts. A database containing the expert descriptions of the meditation techniques and experiences was produced by extracting the relevant material from the publications and coding that material to differentiate individual features. The database, which forms part of the supplementary material for this paper, identifies each feature of the contentless experiences referred to in the expert texts, including silence/quietness. Our key finding is that the experts indicate silence/quietness has a particular connection with stillness, and the absence of concepts, mental activity/noise, thoughts, and disturbance. Further analysis leads to the following insights. The silence/quietness reflects the absence of thoughts and sounds, and this fits neatly with a conception of silence/quietness as the absence of internal and external noise. In some cases the terms silence and quietness may also reflect the absence of other disturbances such as non-auditory perceptions, mental images, and negative feelings. That would fit with a conception of silence/quietness as complete calm or absence of disturbance. It is not clear from the expert texts how silence/quietness is distinct from other features such as stillness that also reflect the absence of disturbances. As a separate matter, silence/quietness has connections with all the other features of the contentless experiences, but the closeness of the connections varies. Our work uncovers fine distinctions and ambiguities which lead to new research questions that can be explored in future studies.

With a title like “Mind-Altering Drugs: The Science of Subjective Experience”, it is easy to presume that this book is yet another fanciful pseudoscientific journey through the myriad of drug induced human experiences. This is no such book. Instead, Mitch Earleywine has succeeded in putting together a collection of writings by a group of experts that emphasize the science of subjective methods. In many respects a more appropriate title might have been “The Science of Subjective experience: A Survey of Mind-Altering Drugs.” Only a few chapters deviate from this general framework.