Psychophysiology is the science of understanding the link between psychology and physiology.

For example, psychologists are interested in why we may fear spiders and physiologists may be interested in the input/output system of the amygdala. A psychophysiologist will attempt to link the two. He might, for example, try to explain arachnophobia in terms of impulses coming in and out of the amygdala.

Psychophysiology is different from physiological psychology in that psychophysiology looks at the way psychological activities produce physiological responses, while physiological psychology looks at the physiological mechanisms which lead to psychological activity.

For example, a psychophysiologist may look at how exposure to a stressful situation will produce a result in cardiovascular activity.