Academic journal article Psychonomic Bulletin & Review

Judgments of Others' Heights Are Biased toward the Height of the Perceiver

Academic journal article Psychonomic Bulletin & Review

Judgments of Others' Heights Are Biased toward the Height of the Perceiver

Article excerpt

Published online: 16 July 2014

© Psychonomic Society, Inc. 2014

Abstract We examined how observers use one aspect of their own morphology, height, when judging the physical characteristics of other people. To address this, participants judged the heights of people as they walked past. We tested the hypothesis that differences between participant and target height account for systematic patterns of variability and bias in height estimation. Height estimate error and error variability increased as the difference between participant height and target height increased, suggesting that estimates are scaled to observers' heights. Furthermore, participants' height estimates were biased toward two standards, demonstrating classic category effects. First, estimates were biased toward participants' own heights. Second, participants biased height estimates toward the average height of the target distribution. These results support past research on using both the body and categorical information to estimate target properties but extend to real-world situations involving interactions with moving people, such as height judgments provided during eyewitness testimony.

Keywords Body-scaling · Category effects · Bias · Height estimation

The present study sought to examine how observers use their own morphology when judging physical characteristics of other people. Research on embodied cognition suggests that individuals use their own bodies to scale perceived extents in the environment (Proffitt & Linkenauger, 2013). For example, individuals scale the size of graspable objects to their hand size (Linkenauger, Witt, & Proffitt, 2011); within the range of 0.2-2.5 eye heights (EHs), people scale target height to EH (Sedgwick, 1973; Wraga & Proffitt, 2000); and they scale step height to leg length (Warren, 1984). We examined whether individuals use one aspect of their own morphology, height, to scale the apparent height of other people, which could lead to systematic patterns of bias and variability in judgments.

Sedgwick (1973) first demonstrated that perceived object size can be scaled relative to an observer's own EH when both the observer and object are positioned on the same, flat ground plane. The observer's straight-ahead gaze intersects with the horizon line, creating a ratio between the extent from the observer's EH to the top of the object and the extent from the observer's EH to the ground (Fig. 1). This ratio is a distance-invariant source of information that can be used to scale object height and is specified by the visual angles relating the top and bottom of the object to observer EH.

There is experimental evidence that observers use their EHs to scale object size. For example, Wraga (1999) lowered participants' EHs using a false floor, which led to overestimations of target height. In addition, Bertamini, Yang, and Proffitt (1998) asked participants to judge which of two visible targets was taller and found that discrimination was best when the targets were near participants' EHs; this effect is found not only during perception, but also when individuals are asked to compare the height of a visible target with that of one held in memory (Twedt et al. 2012).

To date, research on the EH scaling of height has been limited to judgments about stationary objects such as poles. It is not known what role observer height may play in the judgments of real ambulatory people who are socially and ecologically relevant targets. Moving targets also introduce variability and uncertainty to judgments, which may affect the degree to which individuals will rely on their own bodies to make estimates. To test this, participants in the present study estimated the heights of people who were walking past. Given the natural variability in participants' and targets' heights, we examined whether differences between participant height and target height would lead to systematic patterns of variability and bias in height estimation. …

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