Wednesday, September 26, 2012

Meditation Experience Predicts Introspective Accuracy

I loves me some meditation research. This new study finds that the more meditation experience a person has greater accuracy of subjective reports, especially those involving introspection of one's own internal processes than non-meditators. Take home: More meditation means greater self-awareness.

Meditation Experience Predicts Introspective Accuracy

Kieran C. R. Fox1*, Pierre Zakarauskas2, Matt Dixon1, Melissa Ellamil1, Evan Thompson3, Kalina Christoff1,2

1 Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada, 2 Brain Research Centre, University of British Columbia, Vancouver, British Columbia, Canada, 3 Department of Philosophy, University of Toronto, Toronto, Ontario, Canada


The accuracy of subjective reports, especially those involving introspection of one's own internal processes, remains unclear, and research has demonstrated large individual differences in introspective accuracy. It has been hypothesized that introspective accuracy may be heightened in persons who engage in meditation practices, due to the highly introspective nature of such practices. We undertook a preliminary exploration of this hypothesis, examining introspective accuracy in a cross-section of meditation practitioners (1–15,000 hrs experience). Introspective accuracy was assessed by comparing subjective reports of tactile sensitivity for each of 20 body regions during a ‘body-scanning’ meditation with averaged, objective measures of tactile sensitivity (mean size of body representation area in primary somatosensory cortex; two-point discrimination threshold) as reported in prior research. Expert meditators showed significantly better introspective accuracy than novices; overall meditation experience also significantly predicted individual introspective accuracy. These results suggest that long-term meditators provide more accurate introspective reports than novices.

Full Citation: 
Fox KCR, Zakarauskas P, Dixon M, Ellamil M, Thompson E, et al. (2012) Meditation Experience Predicts Introspective Accuracy. PLoS ONE 7(9): e45370. doi:10.1371/journal.pone.0045370

Here is some of the introduction. The whole article is open access, so you can read it online or download the PDF.


William James exhorted us more than a century ago, “Introspective observation is what we have to rely on first and foremost and always” [1], but for much of the 20th century, psychologists did not regard introspective reports as valid data for scientific inquiry. Some contemporary researchers have doubted the very possibility of accurate introspection [2]; others have demonstrated that while introspective reports may be reliable under simple conditions, reliability decreases with increasing demands on central processing resources [3].

Introspection can of course be defined in many ways; here we mean it in the straightforward manner used by James: “The word introspection need hardly be defined – it means, of course, looking into our own minds” [1]. That is, in its simplest form introspection involves “considerations of our own experience… [and] our own internal states” [4].

‘Introspective accuracy’ (IA) can putatively be quantified by a variety of methods that combine introspective reports of subjective, mental phenomena with some objective (neural, physiological, or behavioral) measure of these same phenomena. A subject's IA with respect to a given task or process is the degree to which their introspective reports agree or correlate with such objective measures [3], [5].

Recent research provides evidence for large inter-individual variability in introspective accuracy, which may be traceable to and predicted by differential grey matter volume in rostrolateral prefrontal cortex (RLPFC)/Brodmann Area (BA) 10 [5]. Individual differences with respect to a given skill invite the question of whether that skill can be ameliorated, and a recent study involving extensive training supports the idea that well-trained subjects can provide accurate and useful introspective reports [6] (though direct improvement of introspection through training has yet to be demonstrated, to our knowledge). Further, RLPFC/BA10, thought to be a key region involved in introspection and metacognitive awareness [7], is amenable to voluntary up- and down-regulation through real-time functional magnetic resonance imaging (fMRI) neurofeedback training [8]. This functional plasticity [8] and structural heterogeneity [5] in frontal regions key to introspection thus provides a possible neural basis for inter-individual differences, and possibly intra-individual enhancements, in introspective accuracy.

In parallel with this renewed interest in introspection, cognitive neuroscience has begun to focus on the family of mental training practices known as ‘meditation’ [9]. Many meditation practices are highly introspective in nature: common techniques direct the meditator's attention toward emotional states, the arising of thoughts, and even the quality and focus of attention itself [10], [12], [13]. This heavy focus on introspection has led to the hypothesis that experienced meditators might possess the capacity for more objective assessment of their own internal states and mental contents (i.e., greater introspective accuracy) [10], [11]. While a recent study examining subjective reports of emotional state alongside objective measures of autonomic arousal found that long-term meditators' introspective reports correlated better with objective measures than did reports from meditation-naïve controls [14], other similar work has shown equivocal results [15], or no differences between meditators and controls [16]. The evidence for enhanced introspective accuracy in long-term meditators, then, remains meager.

One particular meditation technique, vipassana (‘Insight’) meditation (VM), includes paying close attention to the inner experiences (conceptual, emotional, tactile, and visceral) associated with the current state of the body, primarily in order to better develop a non-discursive awareness centered in the present moment [12], [13]. Such practices may involve the meta-representation by the brain of diverse internal bodily responses and states [10], a view supported by a number of neuroimaging studies of VM meditators, as well as subjects engaging in Mindfulness-Based Stress Reduction (MBSR) courses (at heart a secularized version of VM, with a comparable focus on breath sensations, body awareness, etc. [12]). Neuroimaging has shown that among VM and MBSR meditators the insula, a region whose grey matter volume predicts the accuracy of interoceptive reports [17], exhibits increased cortical thickness [18] and grey matter density [19], as well as increased fMRI blood oxygen-level dependent (BOLD) signal during present-centered awareness [20]. VM and MBSR meditators also show structural and functional augmentations of primary and secondary somatosensory cortices, including increased cortical thickness [18] and fMRI-BOLD signal [20]. Finally, VM meditators show significantly thicker cortex [18] (and in Tibetan Buddhist practitioners, increased grey matter density [22]) in RLPFC/BA10, suggesting enhancement of a region strongly implicated in introspection [5], [7], [8], [45].

Despite this converging evidence that introspection and body-awareness may be heightened in VM/Mindfulness meditators, and despite the extensive body of objective data on tactile sensitivity in humans with which subjective reports could be compared, no study has yet examined the accuracy of introspective reports from a representative cross-sectional group of VM practitioners.

VM provides an ideal means of exploring introspective accuracy: the body-scanning meditation (BSM; vedananupassana) practice within this tradition focuses intensively on awareness of ambient tactile experiences of an entirely subjective nature, varying greatly in quality and intensity. Complementary scientific exploration of tactile sensibility has been extensive in humans, and has likewise shown marked variability in regional sensitivity throughout the body. Correlating subjective with objective measures of tactile sensitivity can thus provide a convenient measure of the extent to which introspective reports agree with what is to be expected from neurophysiological measures.

To explore this idea, we first gathered two sets of well-replicated, objective data on tactile sensitivity from previously published research that involved large samples of adults: (i) psychophysical discrimination and (ii) proportion of cortical area dedicated to various body regions in primary somatosensory cortex (S1).
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