envionment, stimulus, stimulus class

A stimulus is any condition, event, or change in the physical world. Michael explains that a stimulus affects the organism's receptors-vision, hearing, smell, taste, cutaneous sense(surface touch, surface pain), kinesthesis (muscle sense), vestibular sense(balance), organic sense(deep touch, deep pain). A stimulus doesn't necessarily have a measurable effect on behavior.

-a response exhibited by another person

-a gradual change in temperature

-a response exhibited by self

A stimulus class has at least two member stimuli. It can be defined functionally(i.e., all members have the same physical properties, such as size, color location), or temporally(e.g., all members are either antecedent or postcedent)

-a group of stimuli with one or more common properties, including temporal or formal properties.

A stimulus class is a group of stimuli that have a common effect on a response class. For example, a stop sign and a flashing red light evoke the same driving behavior. Also, different stimuli that are reinforcers for a particular behavior would also be a stimulus class. 

Discriminative stimuli may have one or more common properties. For example, a green apple, a green truck, and a green piece of paper are all part of a stimulus class that represents green. Control by "greenness" would be demonstrated when an individual correctly selects the green items from an array of different colored items. That is, "greenness" would be the single, common formal feature that evokes the same behavior(selecting the green item).