Alvarez G A, Cavanagh P
Department of Psychology, Harvard University, Cambridge, MA 02138, USA.
Psychol Sci. 2004 Feb;15(2):106-11. doi: 10.1111/j.0963-7214.2004.01502006.x.
Previous research has suggested that visual short-term memory has a fixed capacity of about four objects. However, we found that capacity varied substantially across the five stimulus classes we examined, ranging from 1.6 for shaded cubes to 4.4 for colors (estimated using a change detection task). We also estimated the information load per item in each class, using visual search rate. The changes we measured in memory capacity across classes were almost exactly mirrored by changes in the opposite direction in visual search rate (r2=.992 between search rate and the reciprocal of memory capacity). The greater the information load of each item in a stimulus class (as indicated by a slower search rate), the fewer items from that class one can hold in memory. Extrapolating this linear relationship reveals that there is also an upper bound on capacity of approximately four or five objects. Thus, both the visual information load and number of objects impose capacity limits on visual short-term memory.
先前的研究表明，视觉短期记忆的固定容量约为四个物体。然而，我们发现，在所研究的五类刺激中，容量存在很大差异，从阴影立方体的1.6个到颜色的4.4个（使用变化检测任务估算）。我们还使用视觉搜索率估算了每类中每个项目的信息负荷。我们测量到的各类记忆容量变化几乎完全被视觉搜索率相反方向的变化所反映（搜索率与记忆容量的倒数之间的r2 = 0.992）。刺激类别中每个项目的信息负荷越大（以较慢的搜索率表示），该类别中能够保存在记忆中的项目就越少。推断这种线性关系表明，容量也存在一个大约四或五个物体的上限。因此，视觉信息负荷和物体数量都对视觉短期记忆的容量施加了限制。
