Bae Gi-Yeul, Olkkonen Maria, Allred Sarah R, Wilson Colin, Flombaum Jonathan I
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
J Vis. 2014 Apr 8;14(4):7. doi: 10.1167/14.4.7.
Working memory for color has been the central focus in an ongoing debate concerning the structure and limits of visual working memory. Within this area, the delayed estimation task has played a key role. An implicit assumption in color working memory research generally, and delayed estimation in particular, is that the fidelity of memory does not depend on color value (and, relatedly, that experimental colors have been sampled homogeneously with respect to discriminability). This assumption is reflected in the common practice of collapsing across trials with different target colors when estimating memory precision and other model parameters. Here we investigated whether or not this assumption is secure. To do so, we conducted delayed estimation experiments following standard practice with a memory load of one. We discovered that different target colors evoked response distributions that differed widely in dispersion and that these stimulus-specific response properties were correlated across observers. Subsequent experiments demonstrated that stimulus-specific responses persist under higher memory loads and that at least part of the specificity arises in perception and is eventually propagated to working memory. Posthoc stimulus measurement revealed that rendered stimuli differed from nominal stimuli in both chromaticity and luminance. We discuss the implications of these deviations for both our results and those from other working memory studies.
颜色工作记忆一直是关于视觉工作记忆的结构和限制的持续争论的核心焦点。在这个领域中，延迟估计任务发挥了关键作用。一般来说，在颜色工作记忆研究中，特别是在延迟估计中，一个隐含的假设是记忆的保真度不依赖于颜色值（并且，与此相关的是，实验颜色在可辨别性方面是均匀采样的）。这个假设反映在估计记忆精度和其他模型参数时，对不同目标颜色的试验进行合并的常见做法中。在这里，我们研究了这个假设是否可靠。为此，我们按照标准做法进行了延迟估计实验，记忆负荷为1。我们发现不同的目标颜色引发的反应分布在离散度上有很大差异，并且这些特定于刺激的反应特性在观察者之间是相关的。后续实验表明，特定于刺激的反应在更高的记忆负荷下仍然存在，并且至少部分特异性出现在感知中，并最终传播到工作记忆中。事后刺激测量显示，呈现的刺激在色度和亮度上与标称刺激不同。我们讨论了这些偏差对我们的结果以及其他工作记忆研究结果的影响。
