Probing visual imagery implicitly: Pupil responses to predicted light and dark stimuli Restricted; Files Only
Li, Xiaonan (Spring 2025)
Abstract
Mental imagery—the ability to visualize without sensory input—varies widely across individuals and plays a key role in important cognitive functions. Although widely used, subjective self-reports like the Vividness of Visual Imagery Questionnaire (VVIQ) are prone to bias and may not reliably reflect actual imagery ability. Emerging evidence suggests that pupillary light responses can serve as a physiological marker of visual imagery, with pupils dilating more when imagining dark surfaces than bright ones. This technique is advantageous as it bypasses the need for conscious reporting. However, most prior studies still rely on explicit instruction or cues to elicit imagery, potentially introducing non-imagery confounds like metacognitive processing. As a result, prior approaches may not be able to capture the involuntary or low-level imagery processes.
Here we develop a novel, implicit pupillometry-based paradigm, in which there is no instruction related to visual imagery. The design leverages predictive learning during the occlusion of a moving object, and tracks physiological responses to imagined luminance. In a within-subjects design, forty-nine adult participants repetitively viewed disk-shaped objects rotating between its front (bright) and back (dark) surfaces across the screen. In later phases, the object rotated behind a blocker toward the end of its trajectory, with the side and surface color counterbalanced.
Without explicit instructions to visualize, participants exhibited significantly larger pupil sizes when imagining dark surfaces compared to light ones. This suggests that spontaneous mental imagery can modulate pupil diameter in the absence of instructions or conscious reporting, supporting the validity of this implicit paradigm of visual imagery. Moreover, no significant correlation was found between VVIQ scores and pupil size changes, suggesting a dissociation between voluntary (top-down) and involuntary (bottom-up) imagery processes. The results support the idea that subjective vividness and physiological imagery strength may reflect distinct cognitive systems. This task has the potential to provide a powerful tool for investigating visual imagery across diverse population, significantly advancing the study of visual imagery. By minimizing reliance on language and higher-order cognition, this approach provides a scalable, objective tool for probing the developmental and neural basis of mental imagery.
Table of Contents
Table of Contents
1. Introduction……………………………………………………………………………………………………………...1
2. Method……………………………………………………………………………………………………………......….9
3. Result…………………………………………………………………………………………………...…………....….13
4. Discussion……………………………………………………………………………………………………………....19
5. Reference……………………………………………………………………………………………..………..………..24
6. Appendix……………………………………………………………………………………………………..……...….30
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File download under embargo until 22 May 2027 | 2025-04-09 11:42:54 -0400 | File download under embargo until 22 May 2027 |
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File download under embargo until 22 May 2027 | 2025-04-09 11:43:51 -0400 | File download under embargo until 22 May 2027 |