Elvevåg B, Weickert T, Wechsler M, Coppola R, Weinberger D R, Goldberg T E
Clinical Brain Disorders Branch, National Institute of Mental Health/National Institutes of Health, Room 4S235, MSC 1379, Building 10, Bethesda, MD 20892, USA.
Schizophr Res. 2002 Jan 15;53(3):187-98. doi: 10.1016/s0920-9964(01)00202-x.
Organizing information and knowledge, and hence categorization, requires specifying boundaries between items, concepts and words. Over-inclusiveness in categorization may be seen as looseness of association; over-inclusive thinking was an early description of schizophrenic thinking. Recent studies suggest semantic memory problems in schizophrenia, and that thought disorder is associated with a disorganized semantic network. One such study [Psychol. Med. 24 (1994) 193], using a word categorization task, found patients slowest to respond to items semantically related to, but outside the category, whereas controls were slower responding to items sharing less features of the category (i.e. borderline). The authors suggested that there is an outward shift of semantic category boundaries in schizophrenia. In Experiment 1, we replicated methods, but did not find this qualitative difference in patients (28 patients, 26 controls). We extended this question in Experiment 2 to a more visual domain using pictures that 'morphed' from one entity into another and asked participants to decide when they no longer considered an item to be that item (20 patients, 25 controls). We did not find a difference between patients and controls in their sensitivity to detect boundaries of representations. These two experiments do not support the notion that thought disorder with postulated looseness of association or over-inclusive thinking is related to reduced awareness of boundaries of semantic category membership or entities, and inferentially their featural network. Despite anomalies in the semantic system in schizophrenia, we found aspects to be intact. This specificity of semantic processing is promising, suggesting that research will be informative as to how semantic memory is constructed, and thus how it can selectively break down. Moreover, this study indicates that patients do not 'fail' semantic tasks (e.g. priming) because of globally disorganized decision-making: here their capability to make precise distinctions between representations was intact.
组织信息和知识，进而进行分类，需要明确项目、概念和词语之间的界限。分类中的过度包容性可能被视为联想的松散；过度包容性思维是对精神分裂症思维的早期描述。最近的研究表明精神分裂症存在语义记忆问题，且思维障碍与语义网络紊乱有关。一项此类研究[《心理医学》24 (1994) 193]使用词语分类任务，发现患者对语义相关但不属于该类别的项目反应最慢，而对照组对共享该类别较少特征的项目（即临界项目）反应较慢。作者认为精神分裂症中语义类别界限存在向外偏移。在实验1中，我们重复了方法，但未在患者（28名患者，26名对照）中发现这种质性差异。在实验2中，我们将这个问题扩展到更具视觉性的领域，使用从一个实体“变形”为另一个实体的图片，并要求参与者决定他们何时不再认为一个项目是那个项目（20名患者，25名对照）。我们未发现患者和对照组在检测表征边界的敏感度上存在差异。这两个实验不支持这样的观点，即假定的联想松散或过度包容性思维导致的思维障碍与语义类别成员或实体边界意识降低以及由此推断的其特征网络有关。尽管精神分裂症的语义系统存在异常，但我们发现有些方面是完整的。这种语义处理的特异性很有前景，表明关于语义记忆如何构建以及如何选择性分解的研究将具有启发性。此外，这项研究表明患者并非因为整体决策紊乱而“无法完成”语义任务（例如启动效应）：在这里他们在表征之间进行精确区分的能力是完整的。
