What Is the Berkeley Psychograph?
The Berkeley psychograph (also called the Lee Polygraph) was a portable two-channel polygraph instrument assembled by C.D. Lee of Berkeley, California. Used in criminal testing primarily from the 1930s through the 1950s, it represents an important milestone in the evolution of polygraph technology from laboratory apparatus to practical field instrument.
Design and Features
The Berkeley psychograph included three recording components: a pneumograph for breathing, a cardiograph for cardiovascular activity, and a stimulation marker for annotating the chart. Both physiological channels were recorded simultaneously on moving graph paper. Notably, the instrument was designed to be as portable as a suitcase — a significant innovation at a time when most physiological recording equipment was bulky laboratory apparatus. Lee sold Berkeley psychographs complete with pens, sensors, paper, and instructions.
Historical Significance
The Berkeley psychograph’s portable design enabled polygraph testing to move from university laboratories into police departments and field investigation settings. This transition was essential to the polygraph’s development as a practical tool for criminal investigation rather than purely a research instrument. The two-channel design (breathing and cardiovascular) established the basic recording paradigm that would later be expanded to include electrodermal activity and additional channels in modern polygraph instruments.