Mentalizing Another's Visual World-A Novel Exploration via Motion Aftereffect

Abstract

Past research on level 2 visual perspective-taking (VPT) has mostly focused on understanding the mental rotation involved when one adopts others' perspective; the mechanisms underlying how the visual world of others is mentally represented remain unclear. In three studies, we addressed this question by adopting a novel VPT task with motion stimuli and exploring the aftereffect on motion discrimination from the self-perspective. Overall the results showed a facilitation aftereffect when participants were instructed to take the avatar's perspective. Meanwhile, participants' self-reported perspective-taking tendencies correlated with the aftereffect for both instructed and spontaneous VPT tasks, when the "to-be-adopted" perspective required the participants to mentally transform their self-body clockwise. Specifically, while facilitation was induced for participants with low self-reported perspective-taking tendencies (e.g., viewing a leftward motion stimulus under another's perspective enhanced subsequent perception of leftward motion from the self-perspective), those with high self-reported perspective-taking tendencies showed an adaptation aftereffect (e.g., viewing a leftward motion stimulus under another's perspective weakened subsequent perception of leftward motion from the self-perspective). For these individuals, the adaptation effect indicated the engagement of direction-selective neurons in processing of the subsequent congruent-direction motion from self's perspective. These findings suggest that motion perception from different perspectives (self vs. another) may share the same direction-selective neural circuitry, and this possibility depends on observers' general perspective-taking tendencies.

Keywords: aftereffect; facilitation; mentalization; motion adaptation; visual perspective-taking.

Figure 1

The illustration of a critical trial in the PT condition of Study 1a. After imagining seeing the moving dots from the avatar's perspective for 5 s (A), the subjects made judgments about the dominant moving direction of the test stimulus (B). The arrows in the figure indicate the moving direction of the dots and were not actually presented in the experiments. An example of a complete trial is illustrated in (C).

Figure 2

The effects of viewing motion adaptors on perceived direction of test stimuli under the PT condition (A) and the AO condition (B) in Study 1a, for all participants combined. The threshold of the test stimuli was quantified as the amount of motion coherence that yielded 50% “rightward” responses on the psychometric function curve. Meanwhile, the separation value was quantified as the difference between the two thresholds in the upward and downward adaptor conditions. If the separation value is positive (i.e., the upward-adaptor curve was on the left side of the downward-adaptor curve), it indicates an adaptation effect; if the separation value is negative, it indicates a facilitation effect. The abscissa refers to the motion coherence, with positive values for rightward motion and negative values for leftward motion. Error bars are ±1 SEM.

Figure 3

The correlation between the separation values of psychometric function curves and participants' self-reported PT scores in Study 1a. Negative values of abscissa indicate facilitation effects, whereas positive values indicate adaptation effects.

Figure 4

The relationship between the separation values of motion sensitivity curves and the self-reported PT scores under the PT + Left Avatar condition in Study 2.

Figure 5

The effects of viewing motion adaptors on perceived direction of test stimuli under the PT + Left Avatar condition in Study 2. (A,B) show data from the low and high self-reported PT tendency groups, respectively.

Figure 6

The relationship between the separation values of motion sensitivity curves and self-reported PT scores under the PT + Left Avatar condition in Study 3a.