Psychological Pressure & Board Analysis
It is worthy to note how psychological pressure affects one's ability to accurately perceive the chessboard.
Here is a sample board position from an Online Chess tourney:
At this time in the game I was primarily in fear of losing my knight to trapping and secondarily concerned over my trapped h-rook and how I was starting to lose control of the position, allowing White to gain positional strength and initiative.
All of these concerns had a substantial psychological weight that prevented me from seeing a move that wins outright; even a casual glance reveals it...
But I failed to see it! Why? Because I failed to realize that:
Each move begins the game once again and therefore must be examined fresh and anew as a completely new landscape.
So I always need to remember to take a deep breath and look at the position with fresh eyes regardless of how much pressure I might be under.
Indeed, if I had just taken the time to do that I would of put an early end to this game.