Whenever we perform any action or have a thought in our mind, we rarely wonder whether those belong to us or somebody else. But this seemingly trivial sense becomes very evident in patients with disorders of volition e.g. schizophrenia, alien limb syndrome, etc. where they are sometimes unable to associate agency for their own actions or thoughts.
Generally, when an individual performs a voluntary action (e.g. key press) leading to an outcome (e.g. tone), the perceived time of action and its outcome are shifted towards each other. The amount of shift in perceived time of action towards the outcome is called as action binding, and the amount of shift in perceived time of outcome towards the action is called outcome binding. The overall compression of subjective time between voluntary action and its outcome is famously known as intentional binding and is mostly studied using a Libet’s clock paradigm. Many researchers believe that the compression of subjective time between the voluntary action and its outcome acts as a cue for brain to distinguish between self and non-self action-outcome, and is often used as an implicit measure of sense of agency.
Meditation practices have profound effect on both our physical and mental well-being. But whether meditation practices could also influence sense of agency is unclear. A recent study published in Mindfulness by Lush, Parkinson and Dienes, investigated the effect of mindfulness meditation on intentional binding. In meditator group they had Buddhist mindfulness meditators (N=8) having around 14.6 years of meditation experience and in non-meditator group they had age and gender matched controls (N=8) with no experience of mindfulness meditation.
To measure intentional binding they used the standard Libet’s clock paradigm. Participants performed key press at their will which produced an auditory tone (1000Hz, 100ms) after a delay of 250ms. While they were doing this task, they fixated at the center of the screen displaying a clock face and a dot (0.2o) revolving around it at the speed of 1 revolution per 2560ms. Participants reported the time of action (key press) or outcome (tone) by indicating the position of the dot on the clock face where they thought it was present when that particular event occurred. There were four blocks; 1) contingent action block, 2) contingent outcome block, 3) baseline action block and 4) baseline outcome block. In both, contingent action and contingent outcome block, participants action produced an auditory tone. In contingent action block they were asked to report the perceived time of action whereas in the contingent outcome block they were asked to report the perceived time of outcome. In baseline action block, participants performed only voluntary key press without outcome tone, and reported the time of action. On the other hand, in the baseline outcome block, participants heard a tone randomly between 2.5 to 7 sec without performing any action, and reported the time when they heard the tone.
Mean judgement errors were calculated for each participant and each condition. Action binding and outcome binding were calculated by subtracting the appropriate baseline condition from their respective contingent condition. Overall intentional binding was calculated by subtracting the action binding from outcome binding.
Data was analyzed using Bayesian statistics as it has some advantages over conventional null hypothesis significance testing and is based on accessing the strength of evidence in favor of a particular hypothesis. Bayes factor is used to access strength of evidence. Bayes factor of above 3 indicates substantial evidence in favor of the alternative hypothesis and below 1/3 substantial evidence in favor of the null hypothesis. Bayes factor between 3 and 1/3 indicate data is insensitive in distinguishing between the null and alternative hypothesis.
Results showed that meditators reported more intentional binding compared to non-meditators, specifically the outcome binding was greater in meditators compared to non-meditators. The results suggest that mindfulness meditation shows increase in sense of agency. They explain their results could be due to mindfulness practitioner having greater meta-cognitive access to their intentions, and hence greater intentional binding.
Further evidences with different types of meditation practices and their effect on sense of agency is needed to better understand the relationship between meditation, sense of agency and time perception. Nevertheless, the current study provides a good start in this area, with their results giving hope that meditation practices could also be considered in treating the disorders of volition.
—–Mukesh Makwana, Doctoral student, firstname.lastname@example.org
Source article: Lush, P., Parkinson, J., & Dienes, Z. (2016). Illusory temporal binding in meditators. Mindfulness, 7(6), 1416-1422.