Saliency Bias (also known as perceptual salience) is the tendency to use available traits to make a judgment about a person or a situation.
Salience is how noticeable or observable something is while a bias is an altered way of thinking or perceiving. People tend to emphasize the most noticeable or salient information when explaining causes of behaviors or situations.
When trying to explain someone's behavior people only have the observable external information from that individual. This leads to these salient factors to be most influential when ascribing a cause to someone's behavior.
An example would be someone who watches the news and sees several news stories of violence in their city. Although their likelihood of being a victim of violence has not changed the memory of the violence is very salient in their mind and makes them feel more vulnerable when they go out.