It seems intuitive that the more you imagine a possible event happening, the more likely you will think it is to really happen - even though imagining it doesn't really make it more likely. Our imaginations are powerful things.
But a new study in the Journal of Experimental Psychology found a nuance to this. It turns out that this only happens when there is a valence tag on the imagination. Positive and negative events seem more likely just because you imagined it. But neutral events don't.
It seems to be the arousal of the emotion you put into the imagined event that increases the salience of the memory and thus the perceived likelihood that it will really happen. It isn't like rote learning where you memorize something through pure repetition.