Brilograf

What Is the Brilograf?

The Brilograf was a device for measuring changes in skin resistance, built in the 1940s by criminologist Jacques Bril. Based on similar work Bril had done with Rev. Walter Summers on the Pathometer, the Brilograf was a specialised galvanometric recording instrument designed for use in deception testing. It was not widely adopted and is primarily of historical interest today.

Historical Context

The Brilograf represents one of several independently developed instruments for measuring electrodermal activity that appeared in the mid-twentieth century. During this period, various researchers and practitioners were experimenting with different approaches to recording the electrical properties of the skin, leading to a proliferation of devices before the polygraph industry consolidated around standardised multi-channel instruments manufactured by companies like Lafayette and Stoelting.