Final answer:
Pigeons trained with a 5-second retention interval in the delayed matching-to-sample (DMTS) procedure would show the greatest accuracy in a test where the retention interval is systematically varied from 0 to 10 seconds.
Step-by-step explanation:
In White's research, pigeons trained on a delayed matching-to-sample (DMTS) procedure with a 5-second retention were tested in a procedure where the retention interval was systematically varied from 0 to 10 seconds. According to the research, the pigeons would most likely show the greatest accuracy at a 5-second retention interval. This is because the pigeons were trained with a 5-second retention interval, so they are more likely to perform well at that specific duration.