Final answer:
The team might choose a variable interval 8 (VI8) schedule as the next step for Caleb, doubling the current interval while conservatively building on his success without a drastic change.
Step-by-step explanation:
If Caleb has been responding well to a variable interval reinforcement schedule of 4 minutes (VI4), the team considering the next step might choose to increase the interval to further test and strengthen Caleb's behavior. Given that a VI4 schedule involves reinforcement at unpredictable intervals averaging 4 minutes, a logical next step could be a VI8 schedule. This would double the average time interval, presenting a greater challenge to Caleb and potentially leading to even more robust behavior as he adapts to the longer intervals between reinforcements. Increasing the interval too much might risk a decrease in performance, so choosing VI8 rather than VI12 or VI16 is a conservative approach that builds on the current success without drastically altering the conditions.