Future directions of psychophysical studies

Psychophysics is a very old branch of psychology that is concerned with the relationship between physical stimuli that occur in the "outside world", a nd the sensations they produce in the body's "inside world". According to m odem psychophysical theory, the strength of a sensation is directly related to the intensity of its physical stimulus by means of a power function. Th e history and development of psychophysics is briefly reviewed, and the app lication of psychophysics to manual handling tasks and repetitive hand and wrist motion is described. The advantages and disadvantages of psychophysic s are discussed. The following 4 directions for future research are suggest ed: further validation of the data, expansion into other areas of concern ( eg, other body parts, jobs, and postures), broadening of the subject base b y including symptomatic subjects, and greater inclusion of psychophysical m easures (eg, pain, fatigue, and discomfort) in studies of musculoskeletal d isorders.