A situation in which critical features of the stimulus and the response are the same. For example, this arises when subjects are asked to press the ‚aaleft‚aa key (the response) when they see a dot appear on the left side of the visual field (the stimulus). Humans respond more quickly and with fewer errors in situations of stimulus-response compatibility than incompatibility (the latter occurs if they are asked to press the right key when they see a signal in the left of the visual field). Stimulus-response compatibility can be tested with spatial compatibilities, color (“Press the red key when you see the red signal”), and other dimensions.