Precision in visual working memory reaches a stable plateau when individual item limits are exceeded.
Precision in visual working memory reaches a stable plateau when individual item limits are exceeded.
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DOI：
10.1523/jneurosci.4125-10.2011
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发表时间：
2011-01-19
期刊：
影响因子：
--
通讯作者：
Awh E
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文献类型：
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作者：
Anderson DE;Vogel EK;Awh E
多项研究表明，工作记忆（WM）的分辨率随着存储项目数量的增加而下降。离散资源模型预测，这种下降应该达到一个稳定的平台，在相对较小的集大小，因为项目限制防止额外的信息被编码到WM在较大的集大小。相比之下，灵活资源模型预测，随着集合大小的增加和资源的分布没有任何固定的项目限制，精度的单调下降将无限期地持续下去。在目前的工作中，我们发现WM分辨率呈现单调下降，直到集合大小达到三个项目，之后分辨率达到明显的渐近线。此外，个体差异的分析表明，每个观察员的项目限制和设置的大小WM分辨率达到渐近线之间有很强的相关性。这些行为观察结果得到了对侧延迟活动（CDA）的测量结果的证实，CDA是一种事件相关的电位波形，可以跟踪延迟期间维持的项目数量。CDA活性单调上升，并在预测个人WM容量的一组大小达到渐近线。此外，这种在线存储的神经测量还预测了记忆分辨率达到稳定平台的集合大小。因此，独立的行为和神经测量WM能力支持离散资源模型的明确预测。当超过单个项目限值时，视觉WM的精度达到渐近线。
Multiple studies have demonstrated that resolution in working memory (WM) declines as the number of stored items increases. Discrete-resource models predict that this decline should reach a stable plateau at relatively small set sizes because item limits prevent additional information from being encoded into WM at larger set sizes. By contrast, flexible-resource models predict that the monotonic declines in precision will continue indefinitely as set size increases and resources are distributed without any fixed item limit. In the present work, we found that WM resolution exhibited monotonic declines until set size reached three items, after which resolution achieved a clear asymptote. Moreover, analyses of individual differences showed a strong correlation between each observer's item limit and the set size at which WM resolution achieved asymptote. These behavioral observations were corroborated by measurements of contralateral delay activity (CDA), an event-related potential waveform that tracks the number of items maintained during the delay period. CDA activity rose monotonically and achieved asymptote at a set size that predicted individual WM capacity. Moreover, this neural measure of on-line storage also predicted the set size at which mnemonic resolution reached a stable plateau for each observer. Thus, independent behavioral and neural measures of WM capacity support a clear prediction of discrete-resource models. Precision in visual WM reaches asymptote when individual item limits are exceeded.