Ian howard known internationally as pioneer in sensation/perception research, particularly binocular vision and human spatial orientation. People rely on three types of cues to determine which way is up: visual, gravity, body direction. Area of sensation and perception; psychophysics the study of how physical stimuli are translated into psychological experience. Important contributor to psychophysics; gustav fechner, german scientist. Sensation begins with a stimulus any detectable input from environment. A threshold is a dividing point between energy levels that do and do not have a detectable effect: eg. Hardware stores sell a gadget with photocell that automatically turns a lamp on when a room gets dark. The level of light intensity at which the gadget clicks on is its threshold. An absolute threshold for a specific type of sensory input is the minimum amount of stimulation that an organism can detect: define boundaries of sensory capabilities.