Rats which had just been exposed to a novel stimulus made more additional responses to the stimulus when placed with a rat that had never had experience with the stimulus than when placed with a rat that had had experience with the stimulus. "It was concluded that while the mere presence of another rat will not result in increased exploratory behavior, the exploratory responses of one rat will increase as a result of the exploratory responses made by another." (PsycINFO Database Record (c) 2006 APA, all rights reserved)