Mayer A D, Rosenblatt J S
Dev Psychobiol. 1979 Sep;12(5):407-24. doi: 10.1002/dev.420120502.
The responses of unweaned juveniles, 18 to 27 days of age, in brief tests with pups younger than 10 days were observed during initial exposure and at 4-6-day intervals. They showed no aversive responses and actively sought contact with the pups until 24 days when contact-seeking declined sharply. Young exposed to pups before 24 days continued to seek contact with them after 24 days showing an effect of the prior experience. Juveniles given a choice between young pups and a warm bowl chose the pups; given a choice between young pups and age mates, they chose the young pups until day 23, but chose the age mates after then. When housed continuously with young pups at 22 days of age, 5 of 9 retrieved and grouped pups with a latency of 1 day. Our results indicate that timidity or fear of novelty develops in rats in this situation about Day 24 and thereafter is a factor inhibiting the expression of positive social behavior toward pups.
在最初接触以及每隔4 - 6天的简短测试中，观察了18至27日龄未断奶幼鼠对10日龄以下幼崽的反应。它们没有表现出厌恶反应，而是积极寻求与幼崽接触，直到24日龄时，寻求接触的行为急剧下降。在24日龄之前接触过幼崽的幼鼠在24日龄之后继续寻求与它们接触，显示出先前经历的影响。在幼崽和温暖碗之间进行选择时，幼鼠会选择幼崽；在幼崽和同龄鼠之间进行选择时，它们在23日龄之前会选择幼崽，但之后会选择同龄鼠。当在22日龄时与幼崽持续饲养在一起时，9只中有5只找回并与幼崽聚集在一起，延迟时间为1天。我们的结果表明，在这种情况下，大鼠在大约第24日龄时开始出现胆小或对新事物的恐惧，并且此后这是抑制对幼崽积极社会行为表达的一个因素。
