Department of Psychology, University of Oregon Eugene, OR, 97403.
Department of Psychology, University of Oregon Eugene, OR, 97403
J Neurosci. 2022 Feb 2;42(5):865-876. doi: 10.1523/JNEUROSCI.1396-21.2021. Epub 2021 Dec 22.
Category learning, learning to sort a set of stimuli into categories or groups, can induce category biases in perception such that items in the same category are perceived as more similar than items from different categories. To what degree category bias develops when learning goals emphasize individuation of each stimulus and whether the bias emerges spontaneously during learning itself rather than in response to task demands is unclear. Here, we used functional MRI (fMRI) during encoding to test for category biases in neural representations of individual stimuli during learning. Human participants (males and females) encountered face-blend stimuli with unique first names and shared family names that indicated category membership. Participants were instructed to learn the full name for each face. Neural pattern classification and pattern similarity analyses were used to track category information in the brain. Results showed that stimulus category could be decoded during encoding across many frontal, parietal, and occipital regions. Furthermore, two stimuli from the same category were represented more similarly in the prefrontal cortex than two stimuli from different categories equated for physical similarity. These findings illustrate that a mere presence of category label can bias neural representations spontaneously during encoding to emphasize category-relevant information, even in the absence of explicit categorization demands and when category-irrelevant information remains relevant for task goals. Entities belonging to the same category are perceived as being more similar than entities belonging to different categories. Here, we show that neural representations highlighting category-relevant information form spontaneously during encoding. Notably, the presence of a category label led to neural category bias although participants focused on remembering individual stimuli and category-irrelevant stimulus features remained important for explicit task goals. These results may inform our understanding of bias in general and suggest that bias may emerge when category information is present even when one's explicit focus is on individuals.
类别学习，即学习将一组刺激物分类或分组，可以在感知中引起类别偏见，使得同一类别中的项目比不同类别中的项目更相似。当学习目标强调每个刺激物的个体化时，类别偏见会发展到什么程度，以及这种偏见是在学习过程中自发出现的，还是对任务需求的反应，目前还不清楚。在这里，我们在编码期间使用功能磁共振成像（fMRI）来测试学习过程中个体刺激物的神经表示中是否存在类别偏见。人类参与者（男性和女性）遇到了具有独特名字和共享姓氏的面孔混合刺激物，这些姓氏表明了类别归属。参与者被指示学习每个面孔的全名。我们使用神经模式分类和模式相似性分析来追踪大脑中的类别信息。结果表明，在编码过程中，刺激类别可以在许多额、顶和枕叶区域进行解码。此外，来自同一类别的两个刺激在额前皮质中的表示比来自不同类别、物理相似的两个刺激更相似。这些发现表明，即使在没有明确分类要求且与任务目标相关的类别无关信息仍然相关的情况下，仅仅存在类别标签就可以在编码过程中自发地偏向神经表示，强调与类别相关的信息。属于同一类别的实体被感知为比属于不同类别的实体更相似。在这里，我们表明，在编码过程中，突出与类别相关信息的神经表示会自发形成。值得注意的是，尽管参与者专注于记住单个刺激物，但类别标签的存在导致了神经类别偏见，而与类别无关的刺激特征仍然对明确的任务目标很重要。这些结果可能有助于我们理解一般偏见，并表明即使一个人的明确关注点是个体，当类别信息存在时，偏见也可能出现。
