Vagotonicity of violence: biochemical and cardiac responses to violent films and television programmes.

In a search for a reproducible means of evoking different types of emotional stress it was found that in spite of increased adrenaline secretion slowing of the heart occurred when watching violent television programmes. Further evidence of increased vagal tone was provided by the "sinus arrhythmia" effect, a widening of the gap between the maximum and minimum heart rates during the respiratory cycle in parts of the humour, violence, and suspense sections of the television programme.Groups of people taken to see two particularly violent films showed similar evidence suggesting vagal overactivity, together with increases in plasma free fatty acids and decreases in triglycerides. As these changes occurred even with beta-blockade it is suggested that they might be caused by non-sympathetically mediated changes in the levels of hormones, such as growth hormone, producing lipolysis.The ability to assess objectively an individual's reaction to viewing violence might make it possible to judge the likely social impact of violent films and television programmes.