Hi RJ.
Using psychology over the board against your opponent?
There is 'psychological offer of a draw.' which can throw the onus on a player
to attempt to win the game if they refuse.
It can backfire, the player offering the draw in what he thinks is a dead postion,
(in the case the offer was not psychological) he then tries to win the game to punish
his opponent for refusing the draw. 'The Psychology Refusal of a Draw!'.
Lasker said something like the best move you can play is one that
upsets your opponent. (giving checkmate is pretty upsetting.)
There are a few cases of him not playing what was deemed not the best move
to steer the game into positions that he thought were unsuitable to his opponent.
Getting the Queens off against an attacker, or even attacking a known aggressive
player. (Lasker followed this path against Marshall a few times.)
At the lower levels I've often said (in jest after seeing the amount of won
games lost) It can be be a good ploy to give your opponent a won game because
then he really is in trouble.
You appear to have blundered/sacced a pawn and got some play for it.
Your opponent was not up to the task, slipped in a few bad moves and you won.
You are right in saying:
"I believe he may become overly confident of his winning chances..."
He should have tidied up his position, brought the Rooks into the game and
if needs be, sac the pawn back.
You could argue that this was down to psychology but I'd go along with
inexperienced chess play. At that level any psychology introduced into the
game will be superseded by a few clumsy moves on both sides.
Psychology is, I think anyway, is how you feel before a game and the inner
psychological battles that goes on within yourself when you play.
BTW you missed a neat wrap up.
Instead of grabing the Knight with 32.bxc4 how about...
[FEN "2q2k2/6bp/p5p1/1p1B1p2/2np1B2/1P6/P4PPP/2Q1R1K1 w - - 0 1"]
1. Qa3+ Nxa3 2. Bd6