A lesson in Calculation

Recently i lost a game. wel i do tend to lose quite a lot of games lately so after this loss i sat down and started thinking why i lost this time.

Could it be that i have not yet mastered a certain concept or competence enough?

Going through the game i noticed i missed a move in a variation. the question is why did i miss that move.

let's look at the position.

here i played Bxh7?

what made me do this?

My calculation is as follows: after Kxh7 Ng5+ i calculated Kg8 or Kh8 wil mate (which is not true because after Qh5 Nf6 will hold everything)

so i reasoned Kg6 is the strongest move and i'll follow up with Qg4.

on this move black can only play two good moves f5 en Nf6

on f5 white would play Qg3 and after f4 a simple exf4 will do but on the other variation (Nf6) i reasoned that after Qg3 black had blown all his cookies.

What on earth made me think that!! i found out i has to be a latent image of the other variation (the one with f5) that messed up my calculation of the line.

so my conclusion is: i need to work on my calculating abilities. also i need to develop a healthy way of thinking in which every variation needs to be imagined 'from scratch' (the start of the variation)

i tent to think that our brain also does some caching (like in computers) the crux of this whole story is that proper calculation can only be done by proper and healthy thinking that is not blurred or mixed with alternate lines.

How to achieve this way of thinking? fortunately there is a nice video on chess.com

http://www.chess.com/blog/TigerLilov/learn-how-to-calculate-successfully