Why we make dumb mistakes

Post by RC, Sep 30, 2016.
Psychology Mistake

A couple of days ago I placed an order for 6V 1A AC to DC power transformers. I was so confident that I am ordering correct parts for my project that I went ahead and placed an order for 100 units ($9 each). These transformers are used with linear regulators, LM317, to produce an output voltage of 3.4V. I need to use linear power supply to improve noise immunity of some of my circuits. Everything would be fine if I remembered that my linear regulators run from a minimum of 10V power and what I was suppose to order is actually 12V 1A supplies. Hopefully I can return them back and get correct parts. I got very upset about the stupid mistake I just made and started browsing the internet on the subject why we (or I, in this case) make dumb mistakes. I have found the following article on Psychology Today:
Making Stupid Mistakes by Dr. Ken Eisold. Basically the article says that I have convinced myself that 6V was the correct component rating. I have to say that I agree with the article, because on my desk, prior to placing my order, I have found 12V 1A transformer a left over from the last order I have made and I thought to myself that 12V was wrong and it should be 6V instead.
Psychology works, tested on myself !