Converse effects occur in descending series.
This suggests that the events that follow the termination of a series may produce shifts in the frequencies of response such as we have observed. The introduction of a long delay before the next series is begun, or the experimenter's announcement of a rest period at the end of a series might also operate in this way. To state it another way, if the behavior of S is changed at the end of a series, the responses preceding that change will tend to occur with higher frequency when the situation recurs. Similarly, the longer the series, the greater the effect. This post hoc hypothesis accounts for the results already reported.