Factors in the waning of muricide in the rat: I. Analysis of intra‐ and intersession decrement

If each mouse killed by a rat is removed from the rat's home cage and replaced immediately by another live mouse, the rate of killing declines within 1‐ and 3‐hr sessions. Muricide could not then be dishabituated by either a “nonspecific” stimulus (a loud noise) or a specific change in target characteristics (a frog substituted for the mouse). By systematically varying intersession intervals, we found that 1 hr of ad lib killing produced a monotonically decreasing suppression of muricide over the succeeding 96 hr. Subjects performed an interesting kind of forward didng which was influenced by both dishabituating stimuli and killing; this may be a form of die placement behavior.