method of limits
a psychophysical procedure for determining the sensory threshold by gradually increasing or decreasing the magnitude of the stimulus presented in discrete steps. That is, a stimulus of a given intensity is presented to a participant; if it is perceived, a stimulus of lower intensity is presented on the next trial, until the stimulus can no longer be detected. If it is not perceived, a stimulus of higher intensity is presented, until the stimulus is detected. The threshold is the average of the stimulus values at which there is a detection-response transition (from yes to no, or vice versa). An alternative procedure, the method of constant adjustment, allows the participant to adjust a stimulus continuously until it can no longer be perceived. See also method of constant stimuli.