This paper contains a pretty balanced view of meditation and what we have discovered so far through scientific methods. It thoroughly acknowledges that more test need to be done to make a firmer conclusion in the future.
What is Mindfulness Meditation?
In current clinical and research contexts, mindfulness meditation is typically described as non-judgmental attention to experiences in the present moment. This definition encompasses the Buddhist concepts of mindfulness and equanimity and describes practices that require both the regulation of attention (in order to maintain the focus on immediate experiences, such as thoughts, emotions, body posture and sensations) and the ability to approach one’s experiences with openness and acceptance.
Components of meditation
It has been suggested that mindfulness meditation includes at least three components that interact closely to constitute (a) process of enhanced self-regulation: (b) enhanced attention control, improved emotion regulation and (c) altered self-awareness (diminished self-referential processing and enhanced body awareness)
Attention is often subdivided into three different components:
Sustained attention vs Selective attention
sustained attention refers to the sense of vigilance during long continued tasks and may involve both tonic alerting and orienting, whereas selective attention may involve either orienting (when a stimulus is present) or executive function (when stored information is involved).
New and advanced meditators
A systematic review that compiled the findings of these studies (as well as the effects on other measures of cognition) concluded that early phases of mindfulness meditation might be associated with improvements in conflict monitoring and orienting, whereas later phases might be mainly associated with improved alerting. It is currently still unclear how different meditation practices differentially affect the specific attentional components.
Emotional regulation
Emotion regulation refers to strategies that can influence which emotions arise and when, how long they occur, and how these emotions are experienced and expressed. A range of implicit and explicit emotion regulation processes has been proposed, and mindfulness-based emotion regulation may involve a mix of these processes
Emotional regulation processes:
Cognitive regulation
These findings are in line with the assumption that the process of mindfulness meditation is characterized as an active cognitive regulation in meditation beginners, who need to overcome habitual ways of internally reacting to one’s emotions and might therefore show greater prefrontal activation.
Awareness, not suppression
Because such a negative correlation will occur when prefrontal regions down regulate limbic activation, it was speculated that the positive coupling between the activity of the two regions after mindfulness intervention might indicate that meditation involves monitoring of arousal rather than a down regulation or suppression of emotional responses, and that it might be a unique signature of mindful emotion regulation.
Identification of self
According to Buddhist philosophy, the identification with a static concept of ‘self ’ causes psychological distress. Dis-identification from such a static self-concept results in the freedom to experience a more genuine way of being. Through enhanced meta-awareness (making awareness itself an object of attention), mindfulness meditation is thought to facilitate a detachment from identification with the self as a static entity and a tendency to identify with the phenomenon of ‘experiencing’ itself is said to emerge.
Self-Awareness
Mindfulness practitioners often report that the practice of attending to present-moment body sensations results in an enhanced awareness of bodily states and greater perceptual clarity of subtle interoception. Empirical findings to support this claim are mixed. Although studies that assessed performance on a heartbeat detection task — a standard measure of interoceptive awareness — found no evidence that meditators had superior performance to non-meditators, other studies found that meditators showed greater coherence between objective physiological data and their subjective experience in regard to an emotional experience and the sensitivity of body regions
Self-regulation
Self-regulation deficits are associated with diverse behavioral problems and mental disorders, such as increased risk of school failure, attention deficit disorder, anxiety, depression and drug abuse.
Replication challenge
Findings on the effects of meditation on the brain are often reported enthusiastically by the media and used by clinicians and educators to inform their work. However, most of the findings have not yet been replicated. Many researchers are enthusiastic meditators themselves.
Bias towards positivity, sample sizes and longitudinal studies
In fact, for meditation studies there is a relatively strong bias towards the publication of positive or significant results, as was shown in a meta-analysis. The methodological quality of many meditation research studies is still relatively low. Few are actively controlled longitudinal studies, and sample sizes are small. As is typical for a young research field, many experiments are not yet based on elaborated theories, and conclusions are often drawn from post-hoc interpretations.
Controlling the variables
It is important to control for variables that may be confounded with meditation training, such as changes in lifestyle and diet that might accompany the meditation practice or the expectancy and intention that meditation beginners bring to their practice. Researchers must carefully determine which variables are integral aspects of the meditation training and which can be controlled for.
Duration of tests
Most of the studies on the effects of short-term (1 week) mindfulness meditation on alerting have not found significant effects, but studies investigating long-term meditators (ranging from months to years) did detect changes in alerting.
New method and equipment requirements
Mindfulness meditation approaches can be divided into those involving focused attention and those involving open monitoring. Even within the same meditation style, practitioners can be at different stages of mindfulness practice. Investigating the distinction between these different stages in terms of brain function will require new advanced tools and methods. For instance, simultaneous multi-level recording — using fMRI and electrophysiology — could provide information on how the brain and body interact to support the meditation practice.
Individual differences
Moreover, individual differences in personality, lifestyle, life events and trainer–trainee dynamics are likely to have substantial influence on training effects, although little is known about these influences. Mood and personality have been used to predict individual variation in the improvement of creative performance following mindfulness meditation.
Cross-sectional studies
Early meditation studies were mostly cross-sectional studies: that is, they compared data from a group of meditators with data from a control group at one point in time. These studies investigated practitioners with hundreds or thousands of hours of meditation experience (such as Buddhist monks) and compared them with control groups of non-meditators matched on various dimensions. The rationale was that any effects of meditation would be most easily detectable in highly experienced practitioners.
Caveats of cross-sectional studies
Although these differences may constitute training-induced effects, a cross-sectional study design precludes causal attribution: it is possible that there are pre-existing differences in the brains of meditators, which might be linked to their interest in meditation, personality or temperament.
Locations of the brains are not firmed up
Because the studies vary in regard to study design, measurement and type of mindfulness meditation, it is not surprising that the locations of reported effects are diverse and cover multiple regions in the brain.
Areas of the brain
An activation likelihood estimation meta-analysis, which also included studies from traditions other than mind- fulness meditation, was conducted to investigate which regions were consistently altered in meditators across studies. The findings demonstrated a global medium effect size, and eight brain regions were found to be consistently altered in meditators
Emotional stimuli
A frequently reported finding is that mindfulness practice leads to (or is associated with) a diminished activation of the amygdala in response to emotional stimuli during mindful states as well as in a resting state, suggesting a decrease in emotional arousal. However, although such results have been reported for meditation beginners, they have less consistently been detected in experienced meditators
Interest in the psychological and neuroscientific investigation of mindfulness meditation has increased markedly over the past two decades. As is relatively common in a new field of research, studies suffer from low methodological quality and present with speculative post-hoc interpretations. Knowledge of the mechanisms that underlie the effects of meditation is therefore still in its infancy. However, there is emerging evidence that mindfulness meditation might cause neuroplastic changes in the structure and function of brain regions involved in regulation of attention, emotion and self-awareness. Further research needs to use longitudinal, randomized and actively controlled research designs and larger sample sizes to advance the understanding of the mechanisms of mindfulness meditation in regard to the interactions of complex brain networks, and needs to connect neuroscientific findings with behavioural data.