Ceja Cristina R, McColeman Caitlyn M, Xiong Cindy, Franconeri Steven L
IEEE Trans Vis Comput Graph. 2021 Feb;27(2):1054-1062. doi: 10.1109/TVCG.2020.3030422. Epub 2021 Jan 28.
Bar charts are among the most frequently used visualizations, in part because their position encoding leads them to convey data values precisely. Yet reproductions of single bars or groups of bars within a graph can be biased. Curiously, some previous work found that this bias resulted in an overestimation of reproduced data values, while other work found an underestimation. Across three empirical studies, we offer an explanation for these conflicting findings: this discrepancy is a consequence of the differing aspect ratios of the tested bar marks. Viewers are biased to remember a bar mark as being more similar to a prototypical square, leading to an overestimation of bars with a wide aspect ratio, and an underestimation of bars with a tall aspect ratio. Experiments 1 and 2 showed that the aspect ratio of the bar marks indeed influenced the direction of this bias. Experiment 3 confirmed that this pattern of misestimation bias was present for reproductions from memory, suggesting that this bias may arise when comparing values across sequential displays or views. We describe additional visualization designs that might be prone to this bias beyond bar charts (e.g., Mekko charts and treemaps), and speculate that other visual channels might hold similar biases toward prototypical values.
柱状图是最常用的可视化形式之一，部分原因在于其位置编码使其能够精确传达数据值。然而，图表中单个柱状条或一组柱状条的复制可能存在偏差。奇怪的是，先前的一些研究发现这种偏差会导致对复制数据值的高估，而其他研究则发现是低估。通过三项实证研究，我们对这些相互矛盾的发现给出了解释：这种差异是所测试柱状条长宽比不同的结果。观察者倾向于将柱状条记忆得更类似于原型正方形，导致对宽高比大的柱状条高估，而对高宽比大的柱状条低估。实验1和实验2表明，柱状条的长宽比确实影响了这种偏差的方向。实验3证实，这种错误估计偏差模式在记忆复制中也存在，这表明在比较连续显示或视图中的值时可能会出现这种偏差。我们描述了除柱状图之外可能容易出现这种偏差的其他可视化设计（如梅克奥图和树形图），并推测其他视觉通道可能对原型值也有类似的偏差。
