When a speaker says four in response to four men seated about a table, his response may be as directly controlled by a property of the situation as men or sitting. But if he says four after checking a dozen rooms, some of which contain men, his response is not a simple tact. It is the result of a special use of the intraverbal linkage, one, two, three, four, where (because he has “learned to count”) he has emitted one response in the sequence whenever he has seen a man and now reports the last response so made. (p. 423)
