(General content note: A lot of my thinking has really changed since the old days of this blog. There’s some weird, mean, and polemic stuff in there.)
[New? Start here: https://meditationstuff.wordpress.com/articles/]
I’ve written before about our capacity to know what’s going on inside us , and I did a link dump about knowing what’s going on inside other people . When we meditate, we’re experiencing our own mindstream. It’s interesting to speculate about the possibility and utility of logical complements: What about meditating on someone else’s mindstream? I don’t mean via psychic powers or telepathy  (well, maybe partly ; I’m agnostic on this, and that’s a long, nuanced, gloriously cognitively dissonant post for another time), I mean empathizing with and modeling the other person’s mindstream, with feedback from them. Meditating with a mindstream not your own.
Remember, people can know feelings and the actual thought content of even strangers above chance . So, what if person A meditated normally and person B took the perspective of A, with B reporting A’s experience, and A reporting accuracy. They could mix in whatever dialogue was needed to help B be more accurate. By the way, when people vocally report what’s going on in their mind when they’re solving math problems, it takes the same amount of time to solve the problem as when they’re silent . I’m not implying that *all* the mental activity going into solving the math problem is conscious and verbal, just that people can report on conscious experience in real time. There’s a huge body of research on the subtleties of so-called “protocol analysis,” that is, reporting on inner experience. In any case, it seems like this could be a beneficial or profound process. Or it could be frustrating, clunky, and unwieldy. I haven’t tried it yet. There are dyad and group meditations being used out there, e.g. see Kenneth Folk’s work, though I believe this is exclusively people reporting their own inner experiences to each other.
“Other Mind Meditation” is of course simple to try out, and I could have tried it out before writing this blog post. But I wanted to get my thoughts and expectations in order, first, because it feels like a really neat, deep practice. My suspicion is that this sort of “spiritual cross-training”  would make both meditators progress faster in their individual meditation because of reflection on the generalized properties of mindstreams, abstractly, as well as the simulation of mindstreams and the necessity of gleaning data from one’s own mindstream. Lots of needing system one and system two to be working closely together, or something.
It’s also interesting to speculate on how this practice might influence adult development , e.g. Loevinger’s (and Cook-Greuter’s) conceptions of so-called ego development [6, 7, 8]. Meditation seems to accelerate ego development , and Wilber seems to think that perspective-taking [13, 20] also accelerates ego development [11, 19].
Anyway, let me sketch this out. Let’s have person M be the Meditator (they don’t even really have to be meditating) and let’s let person O be the Observer. They could be physically co-located or on phone, audio-, or video-chat. For realtime modeling, I suspect in-person would be the least frustrating and most likely to actually be useful and rewarding. They could make eye contact (continuously or intermittently) or not. And O would start attempting to model and describe, possibly starting with more general labels  and attempting to drill down into specific feelings, felt sense, imagery, verbal content… And M would give feedback, possibly stereotyped. (yes, no, warmer, colder, past)
An important piece of this would be privacy, deception, and so forth. O might have something in mind but not want to say it, for a variety of reasons. M might have something going on but not want to provide feedback on it, for a variety of reasons, or M might want to guide O but still be hesitant to communicate around it, for a variety of reasons. And yet, communicating those things (sometimes) might in actuality be very safe, productive, cathartic (e.g. M and O have something in common), or not, so let’s see if there’s a way to facilitate it:
Person O could abstract away content and say a general category (e.g. “feeling”), or O could say “something but don’t want to say it.”
M could reply “Go on just say it.” Or, M could try to model and guess at what O was thinking and try to help O out, because maybe O is misreading that saying it would be a net negative. Or, M could provide no feedback or say “pass,” etc.
M might want to facilitate O’s modeling but feels like they can’t express something, for whatever reason. M could talk around it and try to have O guess.
If “guessing” is mutually ok, and either one manages to “guess,” then that could normalize the deep dark secret, experience, or assertion that’s being withheld. (And, to reiterate, of course it’d always be perfectly ok to withhold or deny experiencing something.)
Indeed, both O and M could each be pretending that certain experiences aren’t happening (e.g. M could deny or “neither confirm nor deny” a read by O), or O could decide not to select that out in the first place. And that would just have to be accepted as part of the deal.
Finally, M might have unattended stuff in their mindstream that O picks up on, and M might deny a particular experience but actually be experiencing it somewhere in consciousness, and M might deny the experience or be incited to find it or generate it or suppress it (and of course they could simply be misunderstanding each other or using language that doesn’t click with the other), and that’s just the tip of the iceberg in terms of how the interactions will inevitably be influencing each other’s mindstreams.
So that’s a first pass at some of the possible dynamics. There are also distinctions that could be made around surface experience and explicit inference or reference to what’s generating those surface dynamics (and all that could be happening in awareness, too). Some jargon could be developed so that some of these bids could be compressed into one-syllable words to make the interaction flow more smoothly and quickly. Anyway, this could be a cool practice. I’ll probably experiment with it and report back. I’ll just leave these quotes, here, not to mention :
feeling understood: “a subject, perceiving that a person experiences what things mean to the subject and accepts him, feels, initially, relief from experiential loneliness, and, gradually, safe experiential communion with that person and with that which the subject perceives this person to represent.” 
mutual understanding: “a significant and valued experience, marked by strong feelings of accomplishment and effectiveness, of empathic harmony with another person, of well-being and peace, and of physiological activation” 
[I got pretty sloppy with a few of these. A couple cites might be only tangentially related to the accompanying assertion. Might have doubled up a few numbers, but you can probably sort out which reference I meant.]
 Plenty of millenia-old stories and manualized stuff about psychic powers in ancient texts. It’s interesting to think about what’s going on here from a cog bias, evo psych, etc., etc., perspective, among other things.
 Cruwys, Tegan, S. Alexander Haslam, Genevieve A. Dingle, Catherine Haslam, and Jolanda Jetten. “Depression and Social Identity An Integrative Review.” Personality and Social Psychology Review (2014): 1088868314523839.
 [via 14] Van Kaam, Adrian L. “Phenomenal analysis: Exemplified by a study of the experience of” really feeling understood.”.” Journal of Individual Psychology (1959).
 Gordon, Ron. “The Effects of Perceived Mutual Understanding in Interpersonal Communication.” (1983).
 Hmm, where did I get this impression? I feel like this is pervasive if not explicit in his work.
 Cook-Greuter, Susanne. “Ego development: Nine levels of increasing embrace.” Unpublished manuscript (2005). http://www.stillpointintegral.com/docs/cook-greuter.pdf
 Cook-Greuter, Susanne R. “Postautonomous ego development: A study of its nature and measurement.” PhD diss., Harvard Graduate School of Education, 1999.
 Pfaffenberger, Angela H., Paul W. Marko, and Allan Combs, eds. The postconventional personality: Assessing, researching, and theorizing higher development. SUNY Press, 2011.
 Wilber, Ken, Terry Patten, Adam Leonard, and Marco Morelli. Integral life practice. Shambhala Publications, 2008.
 Ericsson, K. Anders, and Herbert Alexander Simon. Protocol analysis. MIT-press, 1984.
Hurlburt, Russell T. Investigating pristine inner experience: Moments of truth. Cambridge University Press, 2011.
 Ickes, William. Everyday mind reading: Understanding what other people think and feel. Prometheus Books, 2003.
 Zunshine, Lisa. Why we read fiction: Theory of mind and the novel. Ohio State University Press, 2006.
 Wilber, Ken. Integral spirituality. Shambhala Publications, 2007.
 Wilber, Ken. “An Integral Mathematics of Primordial Perspectives” Retrieved July 12 2014. (2012) http://integrallife.com/integral-post/ways-we-are-together?page=0,11