Availability bias is the mental shortcut or rule of thumb (heuristic) for when people estimate that events that easily come to mind are more likely to happen. (And conversely, that events which are harder to recall are less likely to happen.) Emotionally charged or memorable events tend to come to mind more easily, leading to overestimates of the likelihood of events like shark attacks.
Examples:
An individual heard a story of a child who got sick after a vaccine. Since it is an emotional story, they recall it easily. And they think that it is likely to happen to their child, so they don’t immunize their child.
A person hears a horror story of a woman using a court-appointed lawyer losing custody of her children in a domestic violence case. So she decides not to leave her partner because she thinks that losing custody of her children is very likely to happen.
What it is not:
Placing more importance on information from people you think are attractive or whom you like - that is the halo effect.
