Acuna Bettina D, Sanes Jerome N, Donoghue John P
Department of Neuroscience, Box 1953, Brown Medical School, Providence, RI 02912, USA.
Exp Brain Res. 2002 Sep;146(1):1-10. doi: 10.1007/s00221-002-1092-y. Epub 2002 May 28.
We examined how the brain organizes interrelated facts during learning and how the facts are subsequently manipulated in a transitive inference (TI) paradigm (e.g., if A<B and B<C, then A<C). This task determined features such as learned facts and behavioral goals, but the learned facts could be organized in any of several ways. For example, if one learns a list by operating on paired items, the pairs may be stored individually as separate facts and reaction time (RT) should decrease with learning. Alternatively, the pairs may be stored as a single, unified list, which may yield a different RT pattern. We characterized RT patterns that occurred as participants learned, by trial and error, the predetermined order of 11 shapes. The task goal was to choose the shape occurring closer to the end of the list, and feedback about correctness was provided during this phase. RT increased even as its variance decreased during learning, suggesting that the learnt knowledge became progressively unified into a single representation, requiring more time to manipulate as participants acquired relational knowledge. After learning, non-adjacent (NA) list items were presented to examine how participants reasoned in a TI task. The task goal also required choosing from each presented pair the item occurring closer to the list end, but without feedback. Participants could solve the TI problems by applying formal logic to the previously learnt pairs of adjacent items; alternatively, they could manipulate a single, unified representation of the list. Shorter RT occurred for NA pairs having more intervening items, supporting the hypothesis that humans employ unified mental representations during TI. The response pattern does not support mental logic solutions of applying inference rules sequentially, which would predict longer RT with more intervening items. We conclude that the brain organizes information in such a way that reflects the relations among the items, even if the facts were learned in an arbitrary order, and that this representation is subsequently used to make inferences.
我们研究了大脑在学习过程中如何组织相互关联的事实，以及这些事实随后在传递性推理（TI）范式中是如何被处理的（例如，如果A<B且B<C，那么A<C）。这项任务确定了诸如所学事实和行为目标等特征，但所学事实可以通过几种方式中的任何一种进行组织。例如，如果一个人通过对成对项目进行操作来学习一个列表，这些对可能会作为单独的事实被分别存储，并且反应时间（RT）会随着学习而减少。或者，这些对可能会作为一个单一的、统一的列表被存储，这可能会产生不同的RT模式。我们通过试错法描述了参与者学习11种形状的预定顺序时出现的RT模式。任务目标是选择出现在列表末尾附近的形状，并在此阶段提供关于正确性的反馈。在学习过程中，RT增加，即使其方差减小，这表明所学知识逐渐统一为一个单一的表征，随着参与者获得关系知识，需要更多时间来处理。学习后，呈现非相邻（NA）列表项，以检查参与者在TI任务中的推理方式。任务目标还要求从每个呈现的对中选择出现在列表末尾附近的项目，但不提供反馈。参与者可以通过将形式逻辑应用于先前学习的相邻项目对来解决TI问题；或者，他们可以操作列表的单一统一表征。对于具有更多中间项目的NA对，RT更短，这支持了人类在TI过程中使用统一心理表征的假设。这种反应模式不支持依次应用推理规则的心理逻辑解决方案，后者会预测中间项目越多RT越长。我们得出结论，大脑以反映项目之间关系的方式组织信息，即使这些事实是以任意顺序学习的，并且这种表征随后被用于进行推理。
