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FunctionDesigned by Knight Dunlap for use with Dunlap chronoscopes. It is similar to Roemer's voice key, but unlike Roemer's, it does not have an electromagnet and bell attached. Such voice keys were used to register a reaction by voice (a time measurement of mental acts): whenever the membrane vibrates because of a voice response it touches a nearby contact, electrically stopping a hand on the chronoscope.
ProvenancePsychology Department, William James Hall, Harvard University.