Fougnie Daryl, Asplund Christopher L, Marois René
Department of Psychology, Vanderbilt University, Nashville, TN, USA.
J Vis. 2010 Oct 22;10(12):27. doi: 10.1167/10.12.27.
An influential theory suggests that integrated objects, rather than individual features, are the fundamental units that limit our capacity to temporarily store visual information (S. J. Luck & E. K. Vogel, 1997). Using a paradigm that independently estimates the number and precision of items stored in working memory (W. Zhang & S. J. Luck, 2008), here we show that the storage of features is not cost-free. The precision and number of objects held in working memory was estimated when observers had to remember either the color, the orientation, or both the color and orientation of simple objects. We found that while the quantity of stored objects was largely unaffected by increasing the number of features, the precision of these representations dramatically decreased. Moreover, this selective deterioration in object precision depended on the multiple features being contained within the same objects. Such fidelity costs were even observed with change detection paradigms when those paradigms placed demands on the precision of the stored visual representations. Taken together, these findings not only demonstrate that the maintenance of integrated features is costly; they also suggest that objects and features affect visual working memory capacity differently.
一种有影响力的理论认为，整合后的物体而非单个特征，才是限制我们临时存储视觉信息能力的基本单位（S. J. 勒克和E. K. 沃格尔，1997年）。运用一种能独立估计工作记忆中存储项目数量和精度的范式（W. 张和S. J. 勒克，2008年），我们在此表明，特征的存储并非毫无代价。当观察者必须记住简单物体的颜色、方向或颜色与方向两者时，我们对工作记忆中所存物体的精度和数量进行了估计。我们发现，虽然存储物体的数量在很大程度上不受特征数量增加的影响，但这些表征的精度却大幅下降。此外，物体精度的这种选择性下降取决于同一物体中包含多个特征。当变化检测范式对所存储视觉表征的精度提出要求时，即便在这种范式下也观察到了这种保真度代价。综上所述，这些发现不仅证明整合特征的维持代价高昂；还表明物体和特征对视觉工作记忆容量的影响有所不同。
