High Quality Content by WIKIPEDIA articles! Two-alternative forced choice (2AFC) (and the variant Two-interval forced choice (2IFC)) Task is a psychophysical method for eliciting responses from a person about his or her experiences of a stimulus. Specifically, the 2AFC experimental design is commonly used to test speed and accuracy of choices between two alternatives given a timed interval. It has been developed by Gustav Theodor Fechner. The task is an established controlled measure of choice and is widely used to test a range of choice behaviors in animals and in humans . The basic components of a 2AFC task are 1) two alternative choices presented simultaneously (e.g two visual stimuli), 2) a delay interval to allow a response/choice, 3) a response indicating choice of one of the stimuli.