In a 2013 research report published by the Center for Homicide Research, they find that many also reject the idea of having armed classrooms due to what is termed the "weapons effect", which is the phenomenon in which simply being in the presence of a weapon can increase feelings of aggression. "In Berkowitz & LaPage's (1967) examination of this effect, students who were in the presence of a gun reported higher levels of aggressive feelings towards other students and gave more violent evaluations of other students' performance on a simple task in the form of electric shocks. This finding points to possible negative outcomes for students exposed to guns in the classroom (Simons & Turner, 1974; Turner & Simons, 1976)."