The Psychology of Chess

How powerful do you believe psychology to be in chess? There is an old story that at the Siegen Olympiad the Romanian grandmaster Gheorgiu was playing Bent Larsen. He had a terrible record against the Dane and this had a powerful psychological effect. In the game, Georghiu ended up in a completely winning position and was ready to reach out his right hand to play the killing blow, Knight to Bishop Six. However, at that moment his hand was seized with a convulsive tremble which apparently rendered Georghiu incapable of transferring the piece to the required square. In the act of summoning up sufficient reserves of will-power to overcome this unfortunate and paralytic state of affairs, Gheorgiu overstepped the time limit.
Probably the greatest exponent of psychology in chess was Emmanuel Lasker. He often got into inferior positions, almost voluntarily, if it took his opponent into areas that he felt uncomfortable with. Take a look at this article - The Psychology of Lasker - especially at the elite level psychology has a serious effect. Remember when Korchnoi lost a basic endgame against Kasparov (who studied such endings before the match) back in 1984/5 in the Candidates semi's? Korchnoi then lost faith in his technique, seconds and knew the match was lost even though the scores were then level.