Let's Scare Jessica to Death (1971), directed by John D. Hancock.
Just recently in a mental hospital, Jessica doesn't want to admit that she is seeing strange things. With her husband and a friend she moves to an old farmhouse with an unsettling history. The locals are not very friendly and seem physically marked in strange ways. She's hearing a voice. Is it insanity or something else out there? Something in the lake?
I admire indie horror films made on a shoestring budget with a semi-pro crew. What else was Night of the Living Dead (1968) and The Blair Witch Project? Other examples I've reviewed: Carnival of Souls (1962) and Lemora: A Child's Tale of the Supernatural (1973).
This is much slicker than any of those efforts, while still having an indie ambiance. Photography is rather good and the actors are given time to do their thing. I don't know the budget-- Paramount was the distributor but I don't know if they produced as well.
"Psychological horror" implies slow-moving and inexplicit, which is more or less a fair assessment here. Intimations of the macabre take time to develop. Jessica's suspicion of unnatural horror is wrapped up with questions of her own sanity and doubts about her marriage.
And yet. We're used to our horror being conditioned by music and lighting and a certain action or fantasy gloss. If that is all removed, if the thing just appears in normal daylight without the normal "let's pretend this is real" -- that is scary in a different way.
In the end: probably only for serious fans of the shoestring genre.
The obessieve fan site LetsScareJessicaToDeath.net is now a dead link; you can find earlier versions in the Wayback Machine.
Netflix has the DVD, which has pretty good color and detail for such a minor title.
Later: Shout Factory produced a Blu-ray edition. My thumbnails are from the DVD.