Research has convincingly shown the positive effects of mindfulness meditation practice on attentional mechanisms. I discussed some of these findings in previous blogs, for instance the evidence that mindfulness practice is linked to improved attentional control, which is also evidenced by neural markers that show improved selective attention as well as improved conflict resolution mechanisms.
While the refinement of attention skills certainly is a central aspect of many forms of meditation training, importantly mindfulness practice should also lead to changes in the way how we relate to arising emotions and affective responses. Thus the question concerning the link between attentional and emotional processes arises. Pursuing this question, two recent neuroscientific studies provide some insights into the related neural mechanisms.
In the first study, carried out by Teper & Inzlicht (2013), researchers at the University of Toronto, EEG was recorded while participants engaged in the Colour-Word-Naming Task, also called Stroop task. During this task, participants have to indicate the font colour a word is printed in, while ignoring the actual semantics of the word. The critical condition is when the font colour and the semantic of the word are in conflict, for instance the work BLUE printed in red, thus requiring the response “red”. Attentional control is required to inhibit the automatic reaction of reading the word. While previous studies focused on how meditators process such stimuli, here researchers focused on the brain activity related to the response – in particular the brain activity when participants made an error. A significant amount of previous research has shown that a brain potential (event-related potential) with negative voltage occurs approximately 100 milliseconds after an error is committed. This error-related negativity (ERN) is known to reflect the efficiency of meta-cognitive processes, the ability to be aware of one’s own cognitive states.
In comparison to non-meditators the meditators (with quite varied meditation practices) made significantly fewer errors in the task, indicating superior attentional control. In line with these behavioural differences, their recorded ERN exhibited higher amplitudes, considered to be an indicator of better meta-cognitive processing. All study participants also completed a questionnaire that assesses their level of mindfulness (the Philadelphia Mindfulness Scale, Cardaciotto et al., 2008), which includes the aspects of present moment awareness and of emotional acceptance. Further statistical analysis (for the nerds: serial multiple mediation analysis using bootstrapping procedures) revealed that emotional acceptance influences the relationship between meditation experience and performance on the Stroop task: the fact that participants with more meditation experience made fewer errors in the Stroop task can to a large extent be explained by their heightened emotional acceptance.
The study thus replicates and confirms existing evidence that meditators tend to exhibit better attentional control processes and extends these findings by analysing the ERN a neurophysiological marker of metacognitive awareness. In addition, the role of emotional acceptance – also in relation to cognitive tasks – is highlighted. The study suggests that even when a purely cognitive task like naming the colour of a word is carried out, emotional components may be involved. It might be that with increasing meditation experience, the cognitive processes of meditators are less affected by their emotional states. I discussed other evidence for this interpretation in a previous post.
Challenging emotional states during a cognitive task
In the second study, Mica Allen and co-workers investigated how meditation changes cognitive and emotional processes, by looking at the involved brain areas.
Teper & Inzlicht (2013) provided evidence for the involvement of emotional processes even when performing a purely cognitive task. This study went a bit further by actually challenging emotional states while participants engaged in a task that was similar to the Stroop task that was a focus in a previous post, is carried out.
The task used for testing cognition and emotion in meditation
As before, central to the task was the ability to inhibit pre-potent reactions. In each trial a certain number of identical digits, arranged in a 3 x 3 matrix, were presented. This initial display was followed by an affective picture (positive, negative or neutral) and subsequently a second display of digits arranged in a 3 x 3 matrix, again followed by the same affective picture. At the end of each trial the participants had the task to indicate whether there were more digits in the first or in the second display. Interference was introduced by the (irrelevant) identity of the digits.
For instance, in the display example below consisted of five times the digits “3”. Thus the number five would need to be compared to the second digit-display, while the digit itself (here “3”) is irrelevant and should be ignored. The aim of the additional pictures was to serve as emotional distractors and to interfere with task performance.
How did six weeks of meditation change cognitive processing?
After six week of meditation practice the behavioural performance improved significantly, in the sense that the participants were less disturbed or affected by the irrelevant negative affective pictures. In the active control group this was not the case. Interestingly, these improvements were accompanied by increased brain activity in the dorsolateral prefrontal cortex, an area of the brain that constitutes an important knot in the executive control network. In addition, the more time participants invested in meditation over these six weeks the stronger was the activation in brain areas implicated in the salience network such as the anterior insula and the cingulate cortex.
We are tempted to conclude that these findings indicate the hypothesised progression from improvements of attentional control, indexed by the initial involvement of the executive control network, to improved emotion regulation skills, indexed by the selective involvement of the salience network. This would, indeed be an exciting finding, albeit in competition with previous results (see previous post), which suggest that better emotional acceptance is a prerequisite for improved performance on the Stroop task.
Different meditation practices
We need to be cautious, though, and consider one important detail of the study. As so often, over the course of the study the meditators engaged in different meditations, in this case a set of four mindfulness practices (from focused breath awareness, to body-scanning, to compassion and to open monitoring) that progressively require more emotional awareness. Potentially, the most dedicated participants will also have engaged more with those emotional awareness practices and would thus exhibit more emotion related changes.
Thus, the apparent progression from attention to emotional awareness may be a result of engaging in different types of meditation, rather than of progression in meditation per se. The conclusion that an increase in attentional awareness and meta-cognitive control precedes improved emotional/affective awareness based on these results would thus be a little premature. This consideration highlights again how important it is to study one single form of (mindfulness) meditation practice on its own and for sufficiently long times, if we aim to arrive at a precise and clear understanding of the underlying processes.
We nevertheless gain something interesting from this study: we saw that mindfulness meditation practice can improve metacognitive processes and emotional awareness and that the brain networks we would expect to be involved in this process (in this case the salience network and the executive control network) , indeed appear to be implicated.
References
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Teper, R., & Inzlicht, M. (2013). Meditation, mindfulness and executive control: the importance of emotional acceptance and brain-based performance monitoring. Social Cognitive and Affective Neuroscience, 8(1), 85-92. https://doi.org/10.1093/scan/nss045
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Cardaciotto, L., Herbert, J. D., Forman, E. M., Moitra, E., & Farrow, V. (2008). The assessment of present moment awareness and acceptance: The Philadelphia Mindfulness Scale. Assessment, 15(2), 204-223. https://doi.org/10.1177/1073191107311467
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Allen, M., Dietz, M., Blair, K. S., Van Beek, M., Rees, G., Vestergaard-Poulsen, P., et al. (2012). Cognitive-affective neural plasticity following active-controlled mindfulness intervention. Journal of Neuroscience, 32(44), 15601–15610. https://doi.org/10.1523/JNEUROSCI.2957-12.2012
