WASHINGTON - Policemen who are good at multi-tasking are less likely to shoot unarmed people when feeling threatened, found a new study that created video simulations of such situations.

Heather Kleider, Dominic Parrott and Tricia King, assistant professors of psychology at Georgia State University (GSU), have taken a look at such shooting situations, signs of negative emotion and the capacity to perform multiple mental tasks, simultaneously.

Policemen in the study completed a test of working memory capacity (multi-tasking), and then watched a video of an officer involved in shooting that resulted in his death.

Negative effect and stress indicators were measured, including elevated heart rates and increased sweating.

Following the video, officers participated in a computer-based simulation where they were required to make split-second decisions whether to shoot or not to shoot someone, based on 80 slides that presented a person holding either a gun or a harmless object like a cell phone, for only a fraction of a second. Officers then pressed either a ’shoot’ or a ‘don’t shoot’ button.

Analysing the data, researchers found that lower levels of multi-tasking capacity increased the likelihood of shooting unarmed people among those officers who had higher levels of negative emotionality - a score determined by comparing readings of facial movement and heartbeat rates.

Higher multi-tasking capacity seemed to buffer officers against the negative effects of a threat when making shooting decisions, said a Georgia release.