I listened to Prof. Steven Novella's Great Course entitled "Your Deceptive Mind". He explains, among other tricks of the mind, what is called "confirmation bias". Novella uses the example of the toilet seat. She wants it left down after the husband has used the toilet. He wants to accommodate his sweetheart but sometimes leaves the seat up. You realize, I hope, that it needs to be up to avoid being dampened during use but then, it is important to lower the seat for incoming female use. Novella's point is that each time, the lady seats on a damp porcelain rim, she is quite annoyed. Each time the man lowers the seat and realizes he has done what is needed, he feels good. She collects evidence of her unhappy events while he collects evidence of his happy ones. Each converts the count important to them to a feeling that the evidence supports their viewpoint. Each remembers confirming incidences but doesn't notice the disconfirming ones.
In "Stumbling on Happiness", Prof. Dan Gilbert uses the example of being the unhappy, unlucky recipient of bird droppings. I remember the unpleasant time I took my girlfriend to the Washington zoo. Some birds flew over us and dropped unpleasants on her lovely lilac dress. Neither of us remember the times birds flew over us and did not soil us.
This confirmation bias is well-known among investigators. It is real and it matters. Gilbert emphasizes that the oldest and most accepted definition of probability is successes/ (successes + failures). So, the count of what failed to occur is needed, too. True, getting those counts can be tricky but they matter. The Sherlock Holmes story telling of the detective realizing the importance of the dog's not barking points to the importance of something not happening.
