In conventional usage (especially as affected by several decades of context-free psychology), “psychological” tends to have a reductionistic connotation in explaining behavioral phenomena. That alone is going to land this thread in Great Debates on short notice, unless I miss my guess. (i.e., it invites surmises about what interior needs are met by participating in a process whose participants don’t tend to conceptualize as <strictly> interior).
Theologically and sociologically as well as psychologically, then… youv’e got two interwoven questions: what does prayer do for an individual, and what else and/or different things does prayer do for an individual when performed as part of a group in shared prayer, and/or what does shared prayer do for the group as group?
I’m religious in a fashion that does include the process of prayer (one major reason I use the words “God” and “religion” and so on, instead of inventing my own words or choosing words not associated with religion and spirituality). I’m not, however, a participant in any religion officially shared by plural numbers of people, mine is my own. Therefore no group prayer exists in my spiritual practice.
Sociologically speaking, Emile Durkheim and his contingent (of which I am not, this is an outsider’s report) saw organized religion as a central means by which the culture is emplanted in each new generation so as to keep it alive and thriving. (Ya wanna have a France tomorrow, ya gotta turn babies into Frenchmen, or something along those lines; and religion, at least as much as schooling and periodicals and table manners and whatnot, is a rich repository of ideas and perspectives into which new folk get inculcated). Group prayer prayer simultaneously reiterates through repetition the catechism of what beliefs one should have, and demonstrates the unanimity of the people in these beliefs.
Theologically, from a religiously conservative point of view (which I don’t share, this is again an outsider’s commentary): there is God’s word and a vision therein of what God wants of us, and the delineation of what is good and holy and what constitutes the proper order of things; left to their own devices, people would stray willy-nilly, in their thoughts and in their deeds, and chaos would ensue, evil would ensue, penis would probably ensue. Group prayer unifies people on the proper track — repeating that which is proper encourages people to feel certain in what they believe as long as what they believe is what is being repeated, while helping to drive away malignant doubts and heretical thoughts by confronting them with a solid wall of neighbors relatives and friends whose mindset remains pure and proper and aligned with the wishes of God.
Now, distancing myself from Durkheim and the religious conservatives, I would say instead that while it is both true and vitally true that we as individuals need the connectedness with other people that we can only achieve when we feel we’re all on the same channel, without which we suffer from the lack of “reality-testing feedback” from other folks, the real process of prayer has nothing to do with that.
That is the affair of ordinary social intercourse. We get plenty of it in our everyday communications. If there is something that is needed which is apart from the ordinary everyday processes that bind us and merge us into a unified collective thinking, it’s a process that works * contrary* to that, and that is what prayer is.
Prayer tends to feel subjectively like having a conversation with another person, perhaps because that is the way our minds work. Some religious folks would assert rather strongly that it’s because God is in essence like another person; others would go to more trouble to differentiate between the process, which is personal and subjectively feels like talking to someone, and the identity of that with which one communicates when one prays, which they may assert is not another person and should not be conceptualized as such. I’m in the latter camp, I do not think of God as an “entity”, i.e., a “self” that experiences the passage of time subjectively and has a sequence of thoughts on a given Thursday, and experiences itself as a “self” distinct and apart from an exterior “world” and from other “selves” and so on. But the process of prayer is for me, too, like “talking to someone”.
The real and valid process of prayer works to give individuals a perspective outside and beyond “groupthink”, to transcend the everyday mental social processes and get confirmation and “reality-checking second opinions” from something outside of that — “not of this world” is a phrase that comes to mind, although by “world” the phrase really means the social mindset.
I think of God as a sense of self. You have the individual (your everyday “you”), you have the plural sense of self we invoke when we say “we” or “us”, and then there’s something beyond that, a larger sense of self that would be inclusive of everything, THAT WHICH IS, in the same fashion that “we” or “us” includes the plurality of people. It provides the reality-check not only for the individual but for the group, and the individuals who obtain it often go back into the group to bear messages and convey their visions, for their visions are a reality-check on behalf of the species as a whole. (Which then skeptically parses what is heard and that which is truly wisdom and genuinely rings true and sheds light and so on eventually gets incorporated into the groupthink, modifying it with the new insights and whatnot).
The radical observation is that the process is itself radical and therefore threatening to a conservative, change-fearing culture, and so institutionalized religion and group prayer exist as a sort of vaccine against the real thing, an attempt to take the historical content of such revelations and visions, deck them out in yards of gilded velvet and enshrine them in marble and fine woods and crystal, dwell on the importance of the holiness of the events and the messenger and the messenger’s personalty and the messenger’s divine body and whatnot, while obviating the more disruptive parts of the message and the process that brought it.
So group prayer is part of the taxidermy, IMHO.