Answer:
under water, when the words had been learned under water
Explanation:
They did better recalling the words learned if they did so while they were under water, when the words had been learned under water. This is because when learning something many different and subtle queues/stimuli from the environment become associated with what is being learned. This therefore causes those repeated stimuli trigger what was being learned at that time as a memory, thus allowing the individual to better recall it.
