The unexpected killer: effects of stimulus threat and negative affectivity on inattentional blindness.

Inattentional blindness (IB) occurs when observers fail to detect unexpected objects or events. Despite the adaptive importance of detecting unexpected threats, relatively little research has examined how stimulus threat influences IB. The current study was designed to explore the effects of stimulus threat on IB. Past research has also demonstrated that individuals with elevated negative affectivity have an attentional bias towards threat-related stimuli; therefore, the current study also examined whether state and trait levels of negative affectivity predicted IB for threat-related stimuli. One hundred and eleven participants (87 female, aged 17-40 years) completed an IB task that included both threat-related and neutral unexpected stimuli, while their eye movements were tracked. Participants were significantly more likely to detect the threatening stimulus (19%) than the neutral stimulus (11%) p  =  .035, odds ratio (OR)  =  4.0, 95% confidence interval OR [1.13, 14.17]. Neither state nor trait levels of negative affectivity were significantly associated with IB. These results suggest observers are more likely to detect threat-related unexpected objects, consistent with the threat superiority effect observed in other paradigms. However, most observers were blind to both unexpected stimuli, highlighting the profound influence of expectations and task demands on our ability to perceive even potentially urgent and life-threatening information.