Academic journal article Attention, Perception and Psychophysics

Taken Last, Selected First: The Sampling Bias Is Also Present in the Haptic Domain

Academic journal article Attention, Perception and Psychophysics

Taken Last, Selected First: The Sampling Bias Is Also Present in the Haptic Domain

Article excerpt

Published online: 3 December 2014

© The Psychonomic Society, Inc. 2014

Abstract When people are presented with a pair of images and asked to identify which one is more attractive, their eye gaze shifts gradually toward the image that they eventually choose. This study examined whether this sampling bias also occurs in other sensory modalities by observing participants' behavior in a haptic preference task. The results indicated that the participants tended to sample the chosen item just prior to making their decision when they were instructed to identify their most preferred item (i.e., the "like" task), but not when they were instructed to identify their least preferred item (i.e., the "dislike" task). This indicates that the sampling bias is a general phenomenon regardless of sensory modality. In addition, the sampling bias in the like task was larger when the difference in preference ratings between the paired items was smaller. However, the sampling bias decreased when the two items were given equal preference ratings, despite there being a longer decision time on those trials. This suggests that the sampling bias is not simply related to task difficulty, but is also related to preference formation and/or selective encoding of task-relevant information.

Keywords Gaze bias . Preference . Haptic . Tactile sense . Decision making . Dislike


Making choices between multiple items is a fundamental activity in daily life. For example, when selecting a blouse to purchase in a shop, people usually examine and compare the various candidates repeatedly. Shimojo, Simion, Shimojo, and Scheier (2003) have shown that this looking behavior is related not merely to item evaluation, but also to preference formation. These latter authors tracked the eye movements of individuals who were shown pairs of human faces and asked to decide which face was more attractive. The results showed that participants' eye gazes were initially distributed evenly between the two stimuli, but approximately 1 s prior to making a decision, they gradually shifted their eyes toward the face they subsequently chose. However, this "gaze bias" was significantly weaker when the participants were asked to select the less attractive, or the rounder, of the two faces. As a result of this study, looking behavior in preference-judgment tasks has been well researched in the literature (Glaholt & Reingold, 2009; Krajbich, Armel, & Rangel, 2010;Mitsuda& Glaholt, 2014; Nittono & Wada, 2009; Schotter, Berry, McKenzie, & Rayner, 2010). Although the source of the gaze bias is still being debated, there is evidence indicating that it is not a response-related phenomenon; rather, it may be related to the decision-making process.

Recently, Lindsen, Gurpreet, Shimojo, and Bhattacharya (2011) showed that the behavior of sampling musical excerpts was also biased when participants were asked to choose an excerpt that they liked, but not when asked to choose one they did not like; thus, the observed bias was similar to the gaze bias. These results indicate that these types of biases could be a general tendency in preference-judgment tasks, regardless of the sensory modality. To the best of our knowledge, Lindsen et al. (2011) is the only study that has investigated the sampling bias in preference-judgment tasks in sensory modalities other than vision. Accordingly, we tested whether the sampling bias also exists in the sensory domain of tactile processing.

The present study introduced a two-alternative forcedchoice task that asked participants to indicate their preference for handkerchiefs-a common activity in daily life. We expected that the sampling bias would be larger when the participants had to choose the handkerchief that they liked the most than when they had to choose the one they disliked the most, in accordance with the visual-preference and musicalpreference task literature discussed above. The present study also analyzed the relation between the sampling bias and task difficulty (i. …

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