Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283, United States.
Neuropsychologia. 2010 Jun;48(7):1877-85. doi: 10.1016/j.neuropsychologia.2009.07.023. Epub 2009 Aug 5.
We examined the interaction of content and process in categorizing novel semantic material. We taught patients with Alzheimer's disease (AD) and healthy age-matched seniors a category of plausible novel tools by similarity- and rule-based processes, and compared the results with our previous parallel study of categorization of novel animals, in which AD patients were selectively impaired at rule-based categorization. AD patients demonstrated learning in the novel tool study; however, in contrast to the novel animal study, they were impaired in similarity-based as well as rule-based categorization relative to healthy seniors. Healthy seniors' categorization strategies reflected process irrespective of category content; they frequently attended to a single feature following similarity-based training, and always attended to all requisite features following rule-based training. AD patients' categorization strategies, in contrast, reflected category content; they frequently attended to a single feature when categorizing novel animals by either categorization process, but rarely did so when categorizing novel tools. AD patients' ability to categorize novel tools correlated with preserved recognition memory, a pattern not found in the novel animal study. The category-specific role of memory, along with AD patients' performance profile, suggests content-specific distinctions between the categories. We posit that tool features are relatively arbitrary, placing greater demands on memory, while prior knowledge about animals such as constraints on appearance and feature diagnosticity facilitates the assimilation of novel animals into semantic memory. The results suggest that categorization processes are sensitive to category content, which influences AD patients' success at acquiring a new category.
我们研究了分类新语义材料中内容和过程的相互作用。我们通过基于相似性和基于规则的过程向阿尔茨海默病（AD）患者和健康年龄匹配的老年人教授了一类合理的新工具，并将结果与我们之前对新动物分类的平行研究进行了比较，在该研究中，AD 患者在基于规则的分类中受到选择性损害。AD 患者在新工具研究中表现出学习能力；然而，与新动物研究相反，与健康老年人相比，他们在基于相似性和基于规则的分类中都受到损害。健康老年人的分类策略反映了过程，而与类别内容无关；他们在基于相似性的训练后经常关注单个特征，而在基于规则的训练后总是关注所有必要的特征。相比之下，AD 患者的分类策略反映了类别内容；他们在通过任一分类过程对新动物进行分类时经常关注单个特征，但在对新工具进行分类时很少这样做。AD 患者对新工具的分类能力与保留的识别记忆相关，这在新动物研究中未发现。记忆的类别特异性作用以及 AD 患者的表现模式表明，这些类别之间存在特定于内容的区别。我们假设工具特征相对任意，对记忆要求更高，而对动物的先验知识，如对外观和特征诊断性的限制，有助于将新动物同化到语义记忆中。结果表明，分类过程对类别内容敏感，这影响了 AD 患者获得新类别的成功。
