jolt

Any stimulus change—any jolt—releases hormones that trigger the biologically encoded fight-or-flight response, vestigial from a time when survival depended on being alert to anything in the environment that happened at faster than normal or “natural” speed. The response was designed to keep us from being eaten by cave bears. It was not designed to keep us glued to our TV sets. However, most TV programs do just that. They are scripted to deliver the maximum number of jolts per minute.
—  Culture Jam by Kalle Lasn