The farther, the earlier: perceived depth biases temporal order judgments.

Temporal order perception is essential for understanding the succession of events, and is suggested to be affected by attention or metaphorical space-time mapping. Attention theories predict that near or large objects capture attention and enter into consciousness earlier, while the metaphor hypothesis links the concepts of 'far' and 'past' in many languages, predicting that far objects is perceived as appearing earlier. This study investigated temporal order perception in three-dimensional (3D) space to clarify its underlying mechanism. Across three experiments, participants performed a temporal order judgment task, reporting which of two objects appeared first. Using binocular disparity (Experiment 1) and pictorial depth cues (gradient background and relative size, Experiment 2), we observed a consistent bias: distant and smaller objects were perceived as appearing earlier. Experiment 3 manipulated the congruency of depth cues (disparity and relative size), and the bias was reduced under incongruent conditions, indicating a joint effect of integrating depth information during temporal order perception. These findings reveal a systematic temporal bias in 3D space that challenges attentional accounts and aligns with the linguistic metaphor hypothesis, suggesting that perception is biased by prior knowledge through space-time metaphoric mapping.