23.2 Types of Extension

This fact allows for three general categories of extension based upon the degree to which a novel stimulus shares relevant or irrelevant features with a stimulus that has already gained some measure of control over a particular verbal response. Skinner restricted almost his entire treatment of extension to the tact relationship, and that is perhaps the relationship whose extensions are most interesting. Indeed, the names of the categories are based upon tact extensions. Extension of the mand is treated separately because the mand is somewhat free from stimulus control.