It seems that there is a widespread fear of any Friday which is also the 13th of the month, but there is no rational explanation for this. Records and statistics do not show any increase in bad happenings on such a day. So why does does this belief exist?
Learning theory can provide explanations.
Firstly there is a learned association between Friday 13th and bad luck, an example of classical conditioning. Perhaps we hear people talking about this, and start to notice our own misfortunes that day, they get attentional processing, we become extra aware of them. This apparent support for the bad-day-theory could act as a reinforcer, so the learned association is reinforced by operant conditioning.
Then social learning could contribute, as we see other people, people we respect or admire or have as role models, also supporting the bad-day-theory. After all, the media focus on Friday 13th when it occurs, and even the Stock Market slows down on these Fridays. The number 13 on its own is also associated with bad luck, which is why many tall buildings do not have a named 13th floor and Bollywood movies are not released on the 13th of a month.But Friday seems to give the number 13 an extra depth of ill-warning. Could this be because this combination is not common? Who knows! What we do know is that expectation also is a powerful factor in our cognition. Probably people who believe in the bad-luck-day theory do notice unfortunate happenings on such a day far more than they notice good things, and far more than they notice misfortune on any other day. This then would be an example of a self-fulfilling prophecy.
Friggatriskaidekaphobia is a fear of Friday the 13th