IEEE Trans Vis Comput Graph. 2018 Jan;24(1):574-583. doi: 10.1109/TVCG.2017.2745086. Epub 2017 Aug 29.
Effective communication using visualization relies in part on the use of viable encoding strategies. For example, a viewer's ability to rapidly and accurately discern between two or more categorical variables in a chart or figure is contingent upon the distinctiveness of the encodings applied to each variable. Research in perception suggests that color is a more salient visual feature when compared to shape and although that finding is supported by visualization studies, characteristics of shape also yield meaningful differences in distinctiveness. We propose that open or closed shapes (that is, whether shapes are composed of line segments that are bounded across a region of space or not) represent a salient characteristic that influences perceptual processing. Three experiments were performed to test the reliability of the open/closed category; the first two from the perspective of attentional allocation, and the third experiment in the context of multi-class scatterplot displays. In the first, a flanker paradigm was used to test whether perceptual load and open/closed feature category would modulate the effect of the flanker on target processing. Results showed an influence of both variables. The second experiment used a Same/Different reaction time task to replicate and extend those findings. Results from both show that responses are faster and more accurate when closed rather than open shapes are processed as targets, and there is more processing interference when two competing shapes come from the same rather than different open or closed feature categories. The third experiment employed three commonly used visual analytic tasks - perception of average value, numerosity, and linear relationships with both single and dual displays of open and closed symbols. Our findings show that for numerosity and trend judgments, in particular, that different symbols from the same open or closed feature category cause more perceptual interference when they are presented together in a plot than symbols from different categories. Moreover, the extent of the interference appears to depend upon whether the participant is focused on processing open or closed symbols.
有效的可视化沟通在一定程度上依赖于可行的编码策略的使用。例如，观察者在图表或图形中快速准确地区分两个或多个分类变量的能力取决于应用于每个变量的编码的独特性。感知研究表明，与形状相比，颜色是一种更突出的视觉特征，尽管这一发现得到了可视化研究的支持，但形状的特征也会导致独特性的显著差异。我们提出，开放或封闭的形状（即，形状是否由在空间区域上跨越的线段组成）表示影响感知处理的显著特征。进行了三项实验来测试开/闭类别是否可靠；前两项实验从注意力分配的角度进行，第三项实验则在多类散点图显示的背景下进行。在第一项实验中，使用侧翼范式来测试感知负载和开/闭特征类别是否会调节侧翼对目标处理的影响。结果表明这两个变量都有影响。第二项实验使用相同/不同的反应时间任务来复制和扩展这些发现。这两个实验的结果都表明，当封闭形状而不是开放形状作为目标进行处理时，反应速度更快，准确性更高，当来自同一而非不同的开或闭特征类别的两个竞争形状出现时，处理干扰更多。第三项实验采用了三种常用的视觉分析任务——感知平均值、数量和线性关系，包括开放和封闭符号的单显示和双显示。我们的发现表明，特别是在数量和趋势判断方面，当来自同一开或闭特征类别的不同符号一起出现在图表中时，与来自不同类别的符号相比，它们会引起更多的感知干扰。此外，干扰的程度似乎取决于参与者是专注于处理开放符号还是封闭符号。
