Then the other or then another?

Hi. Please help. Whenever I see a phrase that contains the basic structure of "one or the other" or "one and the other," I envision two items, and whenever I see a phrase that contains the basic structure of "one or another" or "one and another," I envision there being more than two items. For the following, why do you think it is "then the other" rather than "then another"?

He'd run one way, then the other, when he saw his mother coming toward him.