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.

中文翻译：

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真相或平方：纵横比偏差召回位置编码

条形图是最常用的可视化之一，部分原因是它们的位置编码使它们能够精确地传达数据值。然而，图形中单个条形或一组条形的再现可能存在偏差。奇怪的是，之前的一些工作发现这种偏差导致了对再现数据值的高估，而其他工作则发现了低估。在三项实证研究中，我们对这些相互矛盾的发现进行了解释：这种差异是测试条标记的纵横比不同的结果。观看者倾向于将条形标记记住为更类似于原型正方形，从而导致高估具有宽纵横比的条形，而低估具有高纵横比的条形。实验 1 和 2 表明，条形标记的纵横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存在于记忆复制中，这表明在比较顺序显示或视图之间的值时可能会出现这种偏差。我们描述了额外的可视化设计，这些设计可能在条形图（例如，Mekko 图表和树状图）之外容易出现这种偏差，并推测其他视觉渠道可能对原型值持有类似的偏差。