Cohen Jerome, Pardy Sandra, Solway Heidi, Graham Harold
Department of Psychology, University of Windsor, Windsor, Ontario N9B 3P4, Canada.
Anim Cogn. 2003 Jun;6(2):93-104. doi: 10.1007/s10071-003-0168-9. Epub 2003 Apr 29.
Rats were exposed to a radial maze containing six black smooth arms and six wire-grid-covered arms and a striped 'exit arm' in experiment 1. The probability of a black or grid arm being baited (5/6 vs 1/6) with sunflower seeds was associated with its proximal cue for some rats (the Relevant Arm Cue group) but not for others (the Irrelevant Arm Cue group). All rats could terminate a trial and receive a highly preferred morsel of apple by entering the exit arm only after having sampled all six seed-baited arms. Relevant Arm Cue rats usually chose some arms from the more densely baited set before choosing an arm from the less densely baited set and made fewer reentries than Irrelevant Arm Cue rats. Although such clustered, higher choice accuracy in the Relevant Arm Cue group corresponds to human clustered, better recall of verbal items from lists hierarchically organized by categories, these rats did not similarly exhaustively retrieve items (arm locations). That is, when required to terminate a trial by entering the 'exit' arm for an apple morsel after having sampled all seed-baited arms, both groups were equally unable to withhold making nonrewarded premature exits. This nonexhaustive foraging search pattern was maintained in the next two experiments in which the radial maze was reduced to three black and three grid arms along with the striped 'exit' arm and in which black and grid arm cues were paired with number of seeds (eight or one) in an arm for Relevant Arm Cue rats. Although Relevant Arm Cue rats displayed perfect clustering by entering all eight-seeded arms before a one-seeded arm, they made more premature exits and reentries into eight-seeded arms in experiment 2 or when forced to enter all eight-seeded arms in experiment 3 than did Irrelevant Arm Cue rats. These foraging tendencies prevent accurate estimations of the amount of information (i.e., arm locations) rats can 'chunk'.
在实验1中，将大鼠置于一个辐射状迷宫中，该迷宫有六条黑色光滑臂、六条带金属丝网覆盖的臂以及一条有条纹的“出口臂”。对于一些大鼠（相关臂线索组），黑色或带金属丝网覆盖的臂被放置葵花籽诱饵的概率（分别为5/6和1/6）与其近端线索相关，但对于其他大鼠（无关臂线索组）则不然。所有大鼠只有在对所有六条放置种子诱饵的臂都进行采样后，通过进入出口臂才能终止一次试验并获得一块非常受欢迎的苹果。相关臂线索组的大鼠通常在从诱饵较少的一组中选择臂之前，会先从诱饵较多的一组中选择一些臂，并且比无关臂线索组的大鼠重新进入的次数更少。尽管相关臂线索组中这种聚类的、更高的选择准确性与人类在从按类别分层组织的列表中聚类地、更好地回忆言语项目相对应，但这些大鼠并没有类似地详尽检索项目（臂的位置）。也就是说，当在对所有放置种子诱饵的臂都进行采样后，要求通过进入“出口”臂以获取一块苹果来终止试验时，两组大鼠同样无法抑制做出无奖励的过早退出。在接下来的两个实验中，这种非详尽的觅食搜索模式得以保持，在这两个实验中，辐射状迷宫减少到三条黑色臂、三条带金属丝网覆盖的臂以及那条有条纹的“出口”臂，并且对于相关臂线索组的大鼠，黑色和带金属丝网覆盖的臂线索与臂中种子数量（八个或一个）配对。尽管相关臂线索组的大鼠通过在进入有一粒种子的臂之前先进入所有有八粒种子的臂而表现出完美的聚类，但在实验2中，或者在实验3中被迫进入所有有八粒种子的臂时，它们比无关臂线索组的大鼠做出更多的过早退出和重新进入有八粒种子的臂的行为。这些觅食倾向妨碍了对大鼠能够“组块”的信息量（即臂的位置）的准确估计。
