Cognitive bias
Why exciting pictures look more complicated than they are
Open access · cc by · source: Europe PMC
People judge emotionally exciting images as visually more complex, even when the actual visual features are not more complicated.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
The bias was in what the rating scale actually captured, not in the raters' effort.
Judgements can track how a stimulus feels rather than the property being judged. Images rated as highly arousing were consistently judged more visually complex even though algorithmic measures showed no difference in physical detail, and eye movements did not explain the effect.
Evidence for the claim as stated.
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Why exciting pictures look more complicated than they are
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35 participants
A total of 35 female volunteers (ages 18–40) with normal or corrected-to-normal vision participated.
720 images
A total of 720 pictures were used in the experiment: 239 pictures were selected from the International Affective Picture System (IAPS; ) database, and were supplemented by an additional 481 pictures found on the Internet that were thematically similar to pictures in the IAPS (and were adjusted to have the same picture dimensions as the IAPS pictures).
Key findings
The researchers discovered a robust arousal-complexity bias where images rated as highly exciting were consistently perceived as more visually complex, even though mathematical algorithms showed no real difference in physical image details. While listing more word associations partially explained this bias, eye movements did not account for it. When warned about this bias, participants could only slightly reduce its strength, showing that the effect is mostly automatic.
Methodology
Across several experiments, researchers asked female college students to rate the visual complexity, emotional arousal, and pleasantness of natural photographs. In the first study, 35 participants rated 720 images displayed for 2000 milliseconds each. Later studies with smaller cohorts of up to 40 participants tested if this effect persisted with longer display times of 5000 milliseconds, looked at eye movements and word association counts, or gave instructions to actively ignore emotional reactions.
Limitations
First, because the researchers did not experimentally alter the images themselves to test response changes, this study cannot definitively prove a direct causal mechanism. Second, the study exclusively tested female participants, meaning the findings may not apply to males. Finally, because the picture sets contained highly stimulating and potentially shocking images, the results might not hold true for more mundane or abstract visual stimuli.
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