Asymmetric compression of representational space for object animacy categorization under degraded viewing conditions
Asymmetric compression of representational space for object animacy categorization under degraded viewing conditions
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退化观看条件下对象生命分类的表征空间的非对称压缩
DOI：
10.1162/jocn_a_01177
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
T. Carlson
中科院分区：
文献类型：
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作者：
Tijl Grootswagers;J. Ritchie;S. Wardle;A. Heathcote;T. Carlson
有生命性是人脑中对象类别表征中的一个强大的组织原则。使用多变量模式分析方法（MVPA），已经表明，到分类器的决策边界的距离与观察者对相同的生命分类任务的反应时间相关，该分类器被训练用于区分有生命和无生命物体的神经激活模式（Carlson，里奇，Kriegeskorte，Durvasula，& Ma，2014;里奇，Tovar，& Carlson，2015）。使用MEG解码，我们测试了当刺激操作（降级）增加任务难度时，是否存在相同的关系，我们预测这将系统地减少激活模式与决策边界的距离，并增加反应时间。此外，我们测试了到分类器边界的距离是否与线性弹道累加器中的漂移率相关（Brown & Heathcote，2008）。我们发现，距离分类器边界相关的反应时间，准确性和漂移率在一个有生命力的分类任务。分裂的动物性，大脑和行为之间的相关性持续时间较长的时间过程中，有生命的刺激比无生命的刺激。有趣的是，在大脑和行为之间的峰值相关性期间，当检查到分类器边界的距离时，我们发现只有退化版本的有生命的物体，而不是无生命的物体，系统地向分类器决策边界移动。我们的研究结果支持在人类大脑中的有生命和无生命的对象类别的表示不对称。
Animacy is a robust organizing principle amongst object category representations in the human brain. Using multivariate pattern analysis methods (MVPA), it has been shown that distance to the decision boundary of a classifier trained to discriminate neural activation patterns for animate and inanimate objects correlates with observer reaction times for the same animacy categorization task (Carlson, Ritchie, Kriegeskorte, Durvasula, & Ma, 2014; Ritchie, Tovar, & Carlson, 2015). Using MEG decoding, we tested if the same relationship holds when a stimulus manipulation (degradation) increases task difficulty, which we predicted would systematically decrease the distance of activation patterns from the decision boundary, and increase reaction times. In addition, we tested whether distance to the classifier boundary correlates with drift rates in the Linear Ballistic Accumulator (Brown & Heathcote, 2008). We found that distance to the classifier boundary correlated with reaction time, accuracy, and drift rates in an animacy categorization task. Split by animacy, the correlations between brain and behavior were sustained for longer over the time course for animate than for inanimate stimuli. Interestingly, when examining the distance to the classifier boundary during the peak correlation between brain and behavior, we found that only degraded versions of animate, but not inanimate, objects had systematically shifted towards the classifier decision boundary as predicted. Our results support an asymmetry in the representation of animate and inanimate object categories in the human brain.