Photoresistive measurement of the Pavlovian conditioned eyelid response in human subjects.

An inexpensive technique is described for measuring eyelid closure during classical (Pavlovian) conditioning experiments. This technique employs a Coulbourn Instruments Co. densitometric device that focuses a beam of infrared light on the cornea. Reflection of the light is interrupted by the eyelids when they are closed, which is sensed by an infrared detector. The latter causes a voltage change to occur, which can then be measured in a variety of ways. Details of both the hardware required and software developed for this purpose are described.