The shape and color are irrelevant stimulus features

of metonymical extension. The shape and color are irrelevant stimulus features which frequently
accompany the written word “stop.”
 Lesson 27: Extension of the Verbal Mand
 The form of the mand, however, is not determined by a prior stimulus. Therefore, there are no relevant
stimulus features. Whether or not those environmental events which we call establishing operations have
features that can be called either relevant or irrelevant is a complex matter and is beyond the scope of this
introductory tutorial. Although the form of the response is not controlled by a prior stimulus, other stimuli,
including audience variables, may determine whether or not the specific response form is emitted.

 Defining Features
 The response is verbal
 The form of the response is controlled by an establishing operation
 Irrelevant Features

 Lesson 28: Extensions of Verbal Behavior — Private Stimuli
 Most stimuli are capable of affecting several different people in the same way. This fact allows for the
verbal community to differentially reinforce verbal responses when it is training one of its members.
 If the trainer can also make contact with the stimulus at the same time that the learner does, then the trainer
can decide whether or not the learner’s response is appropriate to the stimuli present.
 Private stimuli. Only the individual is in contact with the stimuli arising from some event like a toothache.
The trainer can only assume or infer that the appropriate stimuli are present when someone says
“toothache.”
 Private Stimulus
 Defining Features
 Is a physical energy change
 Is capable of affecting a sense organ
 Affects only one individual; other individuals are not affected
 Irrelevant Features
 Type of energy change
 Function of the stimulus (e.g., reinforcing, discriminative, punishing)
 Receptor
 Type of Stimulus
 Photoreceptor  Light
 Phonoreceptor  Sounds
 Chemoreceptors (gustatory and olfactory) 