At the University of Chicago in the early 1920s, psychology grad student William Blatz built a remote-controlled trick chair that would collapse when he pressed a switch. (It was padded to avoid injury.) Then he had subjects sit in the chair while wearing electrodes to measure heart rate and other vital signs. Blatz’s goal was to “study the physiology of fear under controlled, repeatable conditions.” I think he also probably just wanted to build a remote-controlled trick chair. From Weird Universe:
Blatz offered this description of their reactions:
“The observations of the subjects after the fall, of course, varied, but they were sufficiently in agreement to indicate the arousal of genuine fear in naive subjects. Some examples of these remarks were, ‘startled,’ ‘surprised,’ ‘frightened,’ scared,’ etc. In most cases the subjects cried out, and some called the experimenter by name. They all made some effort to escape, thinking an accident had happened. In all cases they acknowledged that they had not anticipated ‘anything like it at all.’ From these statements, it was concluded that the stimulus was wholly unexpected, and unsuspected.”
The electrodes registered the effect of the fright. The hearts of the subjects began hammering, and their breathing rapidly increased. Blatz also observed “striking changes in the electrical conditions of the body in the nature of an increased development of the electromotive force.”
“Dr. Blatz’s Trick Chair of Terror” (Weird Universe)