Sequential biases on subjective judgments: Evidence from face attractiveness and ringtone agreeableness judgment.

Cosimo Urgesi,Jianrui Huang,Xianyou He,Yian Ren,Han Li,Xiaojin Ma,Yiheng Chen,Tingting Zhao,Xin Zeng

doi:10.1371/journal.pone.0198723

Abstract

When people make decisions about sequentially presented items in psychophysical experiments, their decisions are always biased by their preceding decisions and the preceding items, either by assimilation (shift towards the decision or item) or contrast (shift away from the decision or item). Such sequential biases also occur in naturalistic and real-world judgments such as facial attractiveness judgments. In this article, we aimed to cast light on the causes of these sequential biases. We first found significant assimilative and contrastive effects in a visual face attractiveness judgment task and an auditory ringtone agreeableness judgment task, indicating that sequential effects are not limited to the visual modality. We then found that the provision of trial-by-trial feedback of the preceding stimulus value eliminated the contrastive effect, but only weakened the assimilative effect. When participants orally reported their judgments rather than indicated them via a keyboard button press, we found a significant diminished assimilative effect, suggesting that motor response repetition strengthened the assimilation bias. Finally, we found that when visual and auditory stimuli were alternated, there was no longer a contrastive effect from the immediately previous trial, but there was an assimilative effect both from the previous trial (cross-modal) and the 2-back trial (same stimulus modality). These findings suggested that the contrastive effect results from perceptual processing, while the assimilative effect results from anchoring of the previous judgment and is strengthened by response repetition and numerical priming.

Highlights

When people make judgments of single physical attributes of stimuli presented in a series, sequential effects often occur [1,2] in which judgments of the current stimulus are influenced by the preceeding items
In the Experiments 1 and 2, we examined the existence of sequential biases in face attractiveness and ringtone agreeableness judgment tasks and results revealed that both assimilative and contrastive effects were significant
Taking all factors into account, we argue that the mechanisms of assimilative effect is anchoring effect of the previous judgment on the same kind of stimulus, which are independent of perceptual processing

Summary

Introduction

When people make judgments of single physical attributes of stimuli presented in a series, sequential effects often occur [1,2] in which judgments of the current stimulus are influenced by the preceeding items. The most widely explored sequential effects are assimilative effects and contrastive effects. A contrastive effect refers to a shift in the response in the direction.

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Conclusion