Why do Schloss & Palmer (2011) and Forni et al. (2026) disagree about contrasting hues, and what in their methods could explain it?

Schloss & Palmer (48 Berkeley observers, 992 concentric-square pairs of 32 Munsell-specified colours, continuous harmony scale, 'go naturally together' wording) find harmony falls as hue difference rises. Forni, Darmon and Benzaquen (346 online responses, 13 HSL hues at fixed S=0.8 and L=0.5 on equal-area checkerboards, pick the three most and three least harmonious of 12) find hue-averaged preference highest 160-220 degrees apart but strongly hue-dependent. The papers differ in stimulus layout, saturation/lightness control, response format and sample; neither reports inter-observer agreement in the text read, and neither includes a non-Western harmony sample. Curator qualifications: Schloss & Palmer: 'pair preference and harmony both increase as hue similarity increases'; 'pair harmony decreased as hue difference increased for all cut-combinations'; '992' 11, 'go naturally together' 1. Forni et al.: 'We collected 346 responses from colleagues at École Polytechnique and CFM (France), OIST (Japan), as well as volunteers across Europe'; 'each participant answered a randomly assigned subset of 6 questions out of 13'; 'checkerboard' 2. 'Neither includes a non-Western harmony sample' is too strong for Forni et al.: their 346 responses came partly from colleagues at OIST (Japan), though no nationality or country breakdown is reported. Reword to 'neither reports a country- or culture-level breakdown; Forni recruited partly at an institution in Japan'. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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      "url": "https://www.ebi.ac.uk/europepmc/webservices/rest/PMC3037488/fullTextXML",
      "note": "Schloss & Palmer 2011, Europe PMC PMC3037488 full text XML; Forni, Darmon & Benzaquen 2026, Europe PMC PMC13264017 full text XML"
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      "url": "https://www.ebi.ac.uk/europepmc/webservices/rest/PMC13264017/fullTextXML",
      "note": "Schloss & Palmer 2011, Europe PMC PMC3037488 full text XML; Forni, Darmon & Benzaquen 2026, Europe PMC PMC13264017 full text XML"
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