This began as a comment on a post about secrets at Jung at Heart, but it was growing too long, so for context, read Cheryl Fuller's post first. Some of my thoughts on the psychology of secrets follow.
Shameful or guilty secrets can eat a person alive, but I wonder if there are functions of secrets that are more benign, or even psychically necessary and beneficial. What about secrets in relation to the developmental task of psychological separation and individuation?
Between parent and child, does the ability to keep a few secrets aid differentiation of the self? Perhaps it's reassuring to have a private self holding some secrets that serve a boundary function, marking inner and outer, me and not-me.
Another thought: might secrets also be the equivalent of psychologically venturing away from the parent? Not that this is always a good thing. Separation and individuation are developmentally necessary, but venturing away from the parent also separates the child from protective and comforting functions of the parent that might be helpful in processing a painful secret.
Secrets, in this view, might be good, bad or a mixture of both--having an adaptive side (separation/individuation) and a maladaptive side (pain held inaccessible to the ameliorating effects of the comforting other).
Secrets can also serve to protect the self from the punitive or humiliating parent. This early adaptation could have unfortunate later-in-life implications, driving a person to habitually hold painful secrets, to their own emotional detriment.
Secrets can also protect the other, but that's another discussion.
Thinking about secrets sent me back to an article a friend wrote about the revelation of a secret in therapy. I hadn't looked at it in years, but now I recall where these thoughts about secrets originate for me. She wrote:
"Another aspect of J's secret which I will explore is whether the disclosure [of the secret] represents the surmounting of therapeutic resistance or a deterioration of functioning possibly even resulting in a pathological symbiotic merger."
In her paper, she referenced an article by Elaine Caruth (1985) discussing the revelation of a secret as the equivalent, in some instances, of an unintegrated personality springing a leak. So the revelation of a secret might, in some cases, signal some decompensation or fragmentation.
So do secrets sometimes serve as binders of a core self, holding separate parts of the self in a cohering whole that is defined by one's independent control over the secrets?
Sometimes people talk about little lies they've told and they don't know why they told them because there was no apparent advantage to telling the lie. The truth would not have bothered the receiver of the lie. Could it be reassuring, now and then, for some people to tell a small lie that functions as a healthy refortification of the self? Perhaps for the person who is vaguely out of sorts, the lie, with its implicit secret, tightens things up a bit. And does the production of many such meaningless lies more broadly suggest an unintegrated or inadequately cohering sense of self?