Which of the following is NOT categorized as a verbal operant?

Verbal operants are behavior units that are defined by the function of the verbal response and how it is reinforced. In this context, the correct answer is physical responses, which do not fall under the category of verbal operants. Mands, tacts, and echoics are all types of verbal behavior that involve communication.

Mands are requests and are reinforced by obtaining what is requested. Tacts involve labeling or identifying objects, actions, or events, and are reinforced by social praise or attention. Echoics refer to the repetition of verbal stimuli, usually involving some form of auditory response to another's speech. All these examples emphasize a communicative aspect or function, linking effectively to verbal operants.

In contrast, physical responses do not involve spoken language or communication, and thus do not fit under the definition of verbal operants. They could relate to non-verbal or physical actions rather than verbal behaviors, which is why they are correctly identified as not being verbal operants.