Attentional bias describes how our perception changes based on our current thoughts. We tend to be perceptually biased towards the subjects of our thoughts. This bias is important in understanding the mindset of addicts, as well as mental disorders like depression and anxiety. In the case of smokers, smoking is often the subject of their thoughts. As a result, when they see stimuli related to smoking, they are more likely to have positive feelings toward it. This helps to create the self-reinforcing behavior of smokers. In the case of depression or anxiety, the same happens in reverse. When they observe stimuli that they are nervous or depressed about, they are more likely to remember it, because it is the subject of their thoughts. This makes this stimuli appear more universal than they are, once again creating a self-reinforcing cycle.
Threat-related attentional biases are biases towards perceiving possible threats. In a study in 2009, subjects observed fearful faces, neutral faces, and neutral stimuli. Those with higher anxiety levels perceived the fearful faces more rapidly.