Abstract
Various characteristics of the CS were studied in a one-way delayed-avoidance situation with rats. Greater resistance to extinction was found when the CS-US interval consisted of two CS components presented in a serial order rather than one and when the CS was the onset of a physical stimulus rather than its offset. Duration of the CS did not produce any reliable difference in this study. The data were interpreted mainly by applying an extension of the Solomon and Wynne conservation of anxiety hypothesis.