ABSTRACT
The attempt to introduce ‘categorial’ cues shows the confusion which surrounds the notion of ‘stimulus’. In fact S–R theorists are generally imprecise in their use of this notion. ‘Stimulus’ can generally mean any one of four different types of element. Of course, with a small variation, transfer should still take place, although the response might not be as strong. Thus an animal trained to respond to a circle when presented with a circle and a triangle may transfer this training to a new choice between another figure with round contours and one with jagged edges, and respond to the former. Thus the restriction on the notion ‘stimulus’ or ‘cue’ required by S–R theory is found to be inadequate to the facts. The description that a movement may have qua response may thus vary more widely than the S–R theory can allow.
