Which of the following is a defining feature of a complete DTT trial?

A defining feature of a complete Discrete Trial Training (DTT) trial is the systematic and consistent delivery of trials, which often involves a regular time interval between each trial. This helps in maintaining consistency and predictability in the educational setting for the learner. Maintaining consistent intervals allows the behavior technician to effectively measure learning and responsiveness, ensuring that the learner has appropriate opportunities to engage with the material without becoming overwhelmed or fatigued.

In contrast, the other choices do not accurately capture the structured nature of a complete DTT trial. For instance, while the absence of prompts during the response phase (the first choice) can be part of guiding a learner to independence, it's not a defining characteristic of a DTT trial itself. Additionally, having a single step without reinforcement is not a complete trial, as reinforcement is a fundamental component of the DTT framework to encourage desired behaviors. Using multiple antecedents without a set order goes against the structured approach of DTT, which relies on clear and specific antecedent conditions to elicit a response.