The tendency for the presence of a weapon to draw attention and impair a witness's ability to identify a culprit is called

The answer is the Weapon Focus Effect.

The weapon focus effect is the tendency for witnesses who observe an armed criminal to direct their attention toward the weapon so that they fail to encode and remember information about the perpetrator’s physical appearance as accurately as they would have if no weapon had been visible. This effect can have important consequences for the investigation of a crime, as the police often rely on witnesses’ descriptions of a perpetrator as they attempt to identify a suspect.

answer; clear and present danger test;

answer; francis cecil sumner;