Edited by: Alemka Tomicic, Diego Portales University, Chile
Reviewed by: Clayton Hoi-Yun McClintock, Columbia University, USA; Giorgio Bertolotti, Fondazione Salvatore Maugeri (IRCCS), Italy
*Correspondence: Xiangping Liu
This article was submitted to Psychology for Clinical Settings, a section of the journal Frontiers in Psychology
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Interventions using the “Four Immeasurables Meditations” (FIM) are effective for various outcomes; however, whether increased meditation practice in these interventions leads to better results has not been well investigated. This systematic review included 22 FIM interventions that reported associations between the amount of meditation practice and its outcomes. Despite the heterogeneity in intervention components and outcome variables, there were generally few significant associations between amount of meditation practice and its outcomes. Specifically, only five studies reported that more than half of the calculated results were significant. In comparison with correlations between total amount of practice and overall outcomes, the short-term influence of meditation practice was evaluated in fewer studies; however, it had a better association with outcomes. More studies are required that address the underlying mechanisms that elucidate how meditation practice leads to outcome changes in daily life. In this study, two promising mechanisms with initial evidence were discussed. This review also summarized common methodological issues including a lack of experimental manipulation and inaccurate measuring of meditation practice.
Buddhism emphasizes the cultivation of four “sublime” or “noble” attitudes toward all beings: loving-kindness (friendliness), compassion (willing to cease suffering), appreciative joy (feeling happy for others), and equanimity (calm based on wisdom). These are known as the “four immeasurables” (Sujiva,
LKM | People with neutral emotions or peaceful smiling | “May he/she be free from enmity/danger”/”May he/she take care of himself/herself happily” (Sujiva, |
Loving-kindness | Anger |
CM | People in success or happiness | “May he be free from mental suffering”/”May he be free from physical suffering” (Sujiva, |
Compassion | Hatred |
AJM | People in suffering or sadness | “May he not cease from having whatever material gains acquired.”/”May he continue to have whatever spiritual happiness attained and may he gain even more” (Sujiva, |
Appreciative Joy | Envy |
EM | People in good or bad experience | “He is the owner of his own kamma” (Sujiva, |
Equanimity | Attachment |
Empirical studies on the effects of FIM have increased sharply in recent years, and a series of studies evaluated the effects of interventions based on FIM on various outcomes (Galante et al.,
Meditation practices, regardless of type, consume much time, and energy. Experienced meditators in previous studies often had more than 10,000 h of meditation practice (e.g., Lutz et al.,
In their meta-analysis on FIM, Zeng et al. (
The databases search, which was completed on Feb 23, 2016, included MedlinePlus, ISI Core Journals, PsycInfo, Embase, CINAHL Plus, AMED, and Cochrane Central Register of Controlled Trials. The search set in the title, abstract, and keywords sections was “immeasurable OR immeasurables OR kindness OR compassion OR compassionate OR [(Appreciating OR Appreciative OR Sympathetic OR Empathic) AND Joy] OR equanimity OR metta OR mudita OR karuna OR upekkha” combined with “Meditat* OR Buddhis*,” which were adjusted for different databases.
The inclusion criteria were (a) articles published in a peer-reviewed journal in English, (b) empirical studies addressing interventions wherein at least 50% of major practices were FIM, and (c) studies that reported a relationship between the amount of meditation practice and other variables.
The first two authors reviewed the titles and abstracts of unduplicated records to identify potential relevant articles for full text review; then, they extracted information about the amount of meditation practice from empirical studies on FIM. The reference lists of identified empirical studies were checked for missing articles. We attempted to contact the authors for unexplained selective reports; however, some researchers had not provided contact information or did not reply.
Non-duplicated records (
Among the 78 articles on FIM, 51 articles were concerned with interventions lasting 1 day or longer, and others included 14 cross-sectional studies among long-term FIM meditators and 14 one-shot practice sessions of FIM in laboratory settings. Among these FIM interventions, 20 articles reported a relationship between amount of meditation practice and outcomes, which will be reviewed below. Another 13 studies noted that they checked or recorded the practice time; however, they did not explore the relationship between practice time and its effects. The remaining studies on interventions did not mention practice time. The supplemental material lists the information for each article identified by the systematic literature search.
After the systematic literature search, another two articles (Leppma and Young,
Carson et al., |
RCT: LKM vs. TAU; Pre-Post-FU | LKM: 8 weekly 90-min sessions, 10–30 min of practice at home every day | Patients with low back pain, |
Min spent on LKM practice every day: average 20.8 ± 6.3 min per day | ||
Cohn and Fredrickson, |
15 month longitudinal results of Fredrickson et al., |
Same as Fredrickson et al., |
Remained |
Type and frequency of meditation after interventions, daily amount of meditation for 1 week: 33 recoded as continuers and 37% continuers practiced LKM. Daily minutes of practice for continuers were 5.9 for “occasionally,” 28.4 for “frequent” and 35.2 for “daily” | ||
Fredrickson et al., |
RCT: LKM vs. Waitlist Control, Pre-Post | LKM: six 60-min group sessions held over 7 weeks. Participants were asked to practice LKM at home at least 5 days per week. Control group received same intervention later, and the data were used | Working adults, |
Minutes spent on “meditation, prayer, or solo spiritual activity” every day: average 80 min per week (higher in LKM group than control group), dropped to 60 min per week after interventions | ||
May et al., |
Non-RCT: LKM group vs. non-meditation control group, Pre-Post | LKM: LKM group practiced LKM for at least 15 min per day, 4 days per week, for 8 weeks without weekly course | College students LKM: |
Sum of meditation time in minutes: 485.15 ± 71.31 | ||
Leppma and Young, |
Non-RCT: LKM group vs. interpersonal skill training, Pre-Post | LKM: 6 weekly 60 min group sessions. Required 10–20 min 3 or 4 times per week. Interpersonal skill training: 6 weekly course on interpersonal skill | Master level counseling students. |
Not Available | ||
Weibel et al., |
RCT: LKM vs. Waitlist Control, Pre-Post-8-week FU | LKM: 4 90-min group sessions. Participants were encouraged to practice LKM at home. | University student. |
Time of meditation practice over prior week in minutes: 29 ± 34 at post measurement, 15 ± 29 at follow up |
In one of the earliest empirical studies on LKM, Carson et al. (
Fredrickson et al. (
May et al. (
Leppma and Young (
Weibel et al. (
Six interventions adopted cognitive-based compassion training (CBCT; Pace et al.,
The lack of baseline measurement in the first study (Pace et al.,
Desbordes et al. (
Mascaro et al. (
Another research program (Pace et al.,
Dodds et al. (
Desbordes et al., |
RCT: CBCT (Cognitive Based Compassion Training), Mindful attention training (MAT), and health discussion control group Pre-Post | CBCT & MAT: 2-h class per week for 8 weeks, with an average of 20 min a day outside the class for CBCT and MAT | Healthy adults, CBCT: |
Sum of minutes of meditation practice at home, average 454 ± 205 min | ||
Dodds et al., |
RCT: CBCT vs.wait-list control group. Pre-Post-4-week FU | CBCT: 8 weekly 2-h courses plus booster at 4 weeks after intervention. At-home practice three times per week, average length 30 min | Female breast cancer survivors CBCT: |
Sum of meditation practice in minutes: average 738.5 ± 330.3 min across 8 weeks | ||
Hutcherson et al., |
RCT: CCT (Compassion Cultivation Training) vs. wait-list control group, Pre-Post | CCT: 8 2-h weekly classes, with requirement of 15 min of at-home practice every day | Community adults CCT: |
Average minutes of weekly formal meditation: 101.11 ± 57.00 | ||
Jazaieri et al., |
Same as Jazaieri et al. ( |
Same as Jazaieri et al. ( |
Same as Jazaieri et al. ( |
Same as Jazaieri et al., |
||
Jazaieri et al., |
Same as Jazaieri et al. ( |
Same as Jazaieri et al. ( |
CCT group in Jazaieri et al. ( |
Whether meditation had been practiced that day, increase from 14.8% to 49.4% through interventions | ||
Klimecki et al., |
Same as Leiberg et al. ( |
Same as Leiberg et al. ( |
Healthy female volunteers. |
Hours of practice outside the training day: average 5.7 | ||
Klimecki et al., |
Non-RCT: affect group vs. memory control group | Affect Group: Empathy training and a subsequent compassion training (both are 6-h 1-day courses with practice at home encouraged) Memory control group: Two matched training on memory skill. | Healthy female volunteers, Affect group: |
Duration of daily practice: 98.6 ± 60.91 min in empathy training, 65.72 ± 53.35 min in compassion training | ||
Leiberg et al., |
Non-RCT: CM training vs. memory training | CM training: 1-day 6-h compassion training with at least 2 h of at-home practice Memory training: matched training on memory skill | Healthy female volunteers, CM: |
Hours of practice outside the training day: not available | ||
Mascaro et al., |
RCT: CBCT vs. health discussion control group. Pre-Post | CBCT: 2-h class per week for eight weeks. 20 min at-home practice each day Health discussion group: matched courses without any at-home practice | Community adults, CBCT: |
Self-reported practice of meditation in minutes: 315.9 ± 228.9 total. | ||
Mascaro et al., |
Same as Mascaro et al. ( |
Same as Mascaro et al. ( |
Same as Mascaro et al. ( |
Sum of daily practice of mindfulness and compassion meditations: average 53.1 ± 51.5 and 212.3 ± 190.3 min, respectively, not correlated with each other | ||
Pace et al., |
RCT: CBCT vs. health discussion group. Post only | CBCT: participants attended 50-min class twice per week for 6 weeks Health discussion groups: once per week for 12 weeks during first-semester study groups, twice per week for six weeks in second-semester groups | University students, CBCT: |
Average number of meditation sessions per week (including at-home sessions that exceeded 10 min and total number of in-class meditation sessions). 2.81 ± 1.65 sessions with 20.08 ± 4.54 min per at-home session. Control group attended significantly more classes than meditation group | ||
Pace et al., |
Single group. Pre only | Same as Pace et al. ( |
University students, |
(1) |
Measured by number of sessions per week, details were not available | |
Pace et al., |
RCT: CBCT vs. waitlist control. Pre-Post-six-week FU | CBCT: 1-h classes twice per week for 6 weeks, 30 min of at-home practice with disk every day | Adolescents in foster care system. CBCT: |
Times of meditation practice each day, collected weekly: 17.09 ± 20.69) times over course; increased from first 3 weeks (7.8 ± 8.33 min) to last 3 sessions (11.59 ± 16.37 min) | ||
Reddy et al., |
Same as Pace et al. ( |
Same as Pace et al. ( |
Same as Pace et al. ( |
See Pace et al., |
Jazaieri et al. (
While the above studies were concerned with daily outcomes, two interventions involved the immediate effects of compassion meditation after intervention. Leiberg et al. (
The same research laboratory (Klimecki et al.,
Neff and Germer (
Neff and Germer, |
RCT: Mindful Self-compassion (MSC) vs. wait-list control. Pre-Post-6-month FU-one-year FU | MSC: participants attended 8 2-h weekly meetings, 40 min of practice every day | Community adults MSC: |
Number of days per week of practicing formal meditations (not only compassion meditation), number of times per day practicing informal self-compassion practice: 5.48 ± 1.50 days per week with formal practice, 5.48 ± 5.95 times per day for informal practice | ||
Wallmark et al., |
RCT: Four Immeasurables Intervention (FII) vs. wait-list control group. Pre-Post | Weekly 75-min class for 8 weeks, with 30 min of practice at home every day | Healthy community adults, FII: |
Amount of meditation practice in minutes: 1234.3 ± 342.5 (via personal communication) |
Wallmark et al. (
Among the articles identified by systematic literature search, only 20 out of 51 (39%) articles on FIM interventions evaluated the relationship between amount of meditation practice and dependent (and/or independent) variables, which reflects the fact that current studies on amount of meditation practice or more generally, on active components, are still limited. Among them, four studies (Carson et al.,
The reviewed studies showed large heterogeneity. This review organized studies into LKM, CM, and other interventions; however, no consistent pattern for LKM or CM, or obvious differences between them, were observed. The interventions' contents in each category were also different, and only CBCT participants experienced repeated application. Of note, among all identified articles on FIM interventions, no intervention used AJM or EM as primary meditation practice. Currently, the only empirical study on AJM was an experiment in a laboratory that evaluated the effects of 6 min AJM practice (Zeng et al.,
Regarding outcome variables, among all 22 reviewed studies, 16 studies adopted various self-reported scales to measure daily outcomes, eight studies involved various behavioral tasks with dependent variables (i.e., TSST, RMET, EFP, SoVT, ZPG, dictator game, perception of pain, and attentional blink), five studies used biological or physiological indicators (i.e., IL-6; cortisol; C-reactive protein, ECG), and five studies measured brain activation in different tasks (see Tables
In general, the current review showed that there are relatively few significant associations between outcome variables and amount of meditation practice. Only five studies (Carson et al.,
Additionally, as highlighted by the reviewers of current article, one might question what the meaning is when the whole intervention group is not effective (in comparison with control group), but effect of amount of meditation practice existed. Pace et al. (
Another issue, pointed out by reviewers of current article, is that the length of reviewed interventions was no longer than 8 weekly sessions, which was far shorter than years of meditation practice in traditional Buddhist training. Therefore, researchers should be cautious when generalizing the conclusion. Furthermore, the limited duration of interventions also limit the variance in amount of meditation practice; therefore, it is possible that larger differences in meditation experience (e.g., 10000–50000 h in previous studies; Lutz et al.,
The reviewed studies tended to use the total amount of meditation practice during the whole intervention, rather than the amount of practice in the short term (e.g., during the most recent week), to predict the outcomes. Only four studies measured daily outcomes and explored their relationship with daily meditation practice (Carson et al.,
It is notable that no study explicitly explained why it calculated total amount of meditation or the frequency of short-term practice. It seems that most researchers held the (implicit) assumption that meditation practice has its effects in a cumulative way through long-term practice, while few researchers explored a pattern of short-term change. In addition, although most Buddhist traditions encourage long-term meditation practice, Zen Buddhism claims a potential “sudden change,” which asserts that the enlightenment can occur with an instant revelation (Suzuki,
How meditation practice leads to changes in daily life was not well explained. For example, Fredrickson et al. (
From meditation practice to daily outcomes, one of the potential mechanisms is that repeated meditation practice makes practitioners more effective in an active application of FIM. Therefore, this enhances the effectiveness of emotional regulation when this is needed by practitioners. For example, previous studies showed that active application of CM when seeing the suffering of others generated positive feelings, which could regulate practitioners' emotions and let them approach and help suffering people (Klimecki et al.,
Another mechanism for further investigation is that daily FIM practice affects short-term mental status, such as by inducing positive moods, and this leads to further change in daily life. This mechanism is more consistent with those studies that explored the short-term associations between amount of practice and outcomes as discussed above. Current studies indicated that FIM practice on a given day can influence one's life the same morning (Fredrickson et al.,
The importance of meditation practice was supported by the correlations between the amount of meditation practice and outcomes; however, it is worth noting that this result may be confounded by other factors. The fundamental issue here is that the relationship between amount of meditation and effects in the reviewed studies is essentially correlational. That is, the researchers did not manipulate the amount of meditation practice into high vs. low levels, thus the causal relationships between meditation practice and outcomes cannot be confirmed. Fredrickson et al. (
At the same time, methodological issues can obscure the relationship between meditation practice and effects, even when this relationship exists. The low reliability of meditation practice records has been noted above. Researchers also noted the possibility that the quality of practice is more important than the amount of practice (Shapiro et al.,
Using objective records (e.g., electronic recorder) rather than subjective report to count amount of practice. | |
Using daily or weekly report rather than recalling after the whole intervention. | |
Recording both formal and informal meditation practice. | |
Separating different meditation practice (e.g., different FIM). | |
Measuring not only the time or quantity, but also quality of meditation practice. | |
Figuring out time of meditation experience (i.e., concentration in meditation) rather than time spent on whole meditation practice. | |
Considering the nature of outcomes and explaining why certain outcome should be impacted by meditation practice (or by other components in interventions like didactic components). | |
Considering the nature of outcomes and predicting why meditation should have short term effect or long term effect on certain outcome. | |
Investigating how meditation influences daily outcomes, especially for those outcomes that are not directly targeted in meditations (e.g., perceived stress)? | |
Measuring not only effects on daily outcomes, but also effects on active application of meditation skill. |
Two major limitations of the current review should be noted. First, this review was limited to articles published in journals; other resources, such as dissertations, might add more information. However, we believe the published articles represent the current paradigm in investigating the effects of meditation practice, and our summary of different perspectives and methodological issues should not have been heavily impacted by missing unpublished studies. Second, we discussed the issue of selective reporting, but did not provide a comprehensive risk of bias assessment. This is because the current review focused on associations between amount of meditation practice and outcome variables, which is largely limited to FIM intervention groups and was less concerned with typical risks of bias such as randomization between groups or allocation concealment.
Whether more meditation practice leads to better outcomes in FIM interventions has received insufficient research attention. Current evidence shows that the amount of meditation practice has limited associations with outcomes. In addition to correlations between total amount of practice and daily outcomes, the short-term influence of FIM and the ability of actively applying FIM skills present promising perspectives to understand the contribution of meditation practice. Experimental manipulation and better measurement of meditation practice are needed in future studies.
XZ, FL, and XL designed the study. XZ and FC reviewed articles and analyzed the data. XZ and TO wrote the paper. All authors discussed the results and commented on the manuscript.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We thank two reviewers for their comments and ideas. This study was conducted while XZ was studying at the Chinese University of Hong Kong, and it received support from both Beijing Normal University and the Chinese University of Hong Kong. Dr. Oei is now an Emeritus Professor of UQ and also a visiting Professor of James Cook University, Singapore and Nanjing University, PR China.
The Supplementary Material for this article can be found online at: