Which verbal operant does not require a direct prompt for response?

The correct answer is tact. A tact is a verbal operant that involves labeling or identifying objects, actions, or events in the environment without needing a direct prompt or antecedent. It is often described as an expressive response that comes naturally when an individual encounters something they can describe or name.

In the context of verbal behavior, when someone sees an object and simply states what it is, such as saying "dog" when they see a dog, they are engaging in a tact. This behavior occurs as a spontaneous expression of their observations and experiences, reflecting their understanding of the world around them.

On the other hand, echoic responses require a model or prompt; for instance, repeating a word after hearing it is not a tact but an echoic. A mand, or command, is specifically a request that is prompted by a desire or need, such as asking for water when thirsty. Textual behavior involves reading written words, which also relies on a specific stimulus.

Therefore, tact responses stand apart because they do not rely on any external prompts or antecedents, allowing for spontaneous and natural language use that is closely tied to the context of the environment.