Despite Bobby Fischer's well known "I don't believe in psychology, I believe in good moves", it is widely agreed among the strongest players that psychology is a significant factor in any game. In many games that are played well, there tends to be a lot of quiet moves for a very long time until some inaccuracy somewhere show its face. I just played this game against an anonymous player where neither player did any wrong for 24 moves, and then on White's 25th move, he makes an elementary tactical blunder. Could it be that this player got bored with the lack of loud moves in the game? This game doesn't really provide any evidence but I find it very interesting to look at a game from a psychological perspective and try to figure out what the players may have been thinking.
Here is the game (I know it's not a particularly entertaining game): http://en.lichess.org/bLgbRwkp/black
Here is the game (I know it's not a particularly entertaining game): http://en.lichess.org/bLgbRwkp/black