the extent to which the relationship between stimulus and response facilitates response. Speed and accuracy are affected by this relationship; for instance, a left keypress in response to a stimulus on the left will be quicker and more accurate than a right keypress for a stimulus on the left. This is an example of an element-level compatibility effect, which results from the mapping of individual stimuli to responses within a set. A verbal response to a verbal stimulus is quicker and more accurate than a spatial response to a verbal stimulus. This is an example of a set-level compatibility effect.