中文摘要：

采用“5／4模型”类别结构探讨了类别学习中样例量的预期作用。设置了两种学习条件（“知道样例量”和“不知道样例量”），分别探讨两种学习条件下的学习效率、学习策略以及所形成的类别表征。106名大学生参加了实验，结果表明：在类别学习中，样例量的预期作用显著，知道样例量组的学习效率高于不知道样例量组；样例量的预期作用对类别学习效率的影响是通过影响学习过程中使用的策略来实现的；样例量的预期作用不影响两种学习条件的学习后形成的类别表征，且两种学习条件的被试白始至终表现出样例学习的表征模式。

英文摘要：

This paper explores the effects of category size expectations on category learning. The expectation effect is the finding that category learning is improved when subjects are told how many items or exemplars are in each category in advance. There are three major theories or models of how categories are represented： Rule-based, Prototype-based, and Exemplar-based. Rule-based models assume that category learning is a process of discovering an explicit, verbalizable rule that maximizes categorization accuracy （Ashby, 2005; Seger ＆ Cincotta, 2006）. Prototype-based models assume that stimuli are categorized on the basis of their similarity to category prototypes stored in memory （Rosch ＆ Mervis, 1975; Smith, Chapman, ＆ Redford, 2010; Coutinho, Redford, ＆ Smith, 2010）. A category prototype is generally defined as the average, or most typical, member of a category. Exemplar-based models assume that the categorization of a new exemplar is based on the similarity of the new exemplar to the representations of all previously encountered exemplars stored in memory （Medin＆ Schaffer, 1978; Kruschke, 1992; Nosofsky, 1992）. According to Rule-based and Prototype-based models, people abstract the rule or prototype as their final representation without regard to the total number of exemplars in each relevant category; therefore, knowing how many exemplars are in each category should not affect learning. However, according to Exemplar-based models categories are represented as all the, specific exemplars that have been previously experienced. This implies that knowledge of category size may improve exemplar based categorization learning. Two learning conditions, Known condition （KC） and Unknown＇ condition （UC） were compared in this experiment. In KC participants were instructed as to how many total exemplars （9） they would see across both categories. In UC participants were given no information about category size. The ＂5-4 category structure＂ from Medin and Schaffer （1978） was adapte