Table 1 MODEL 1: Pupil responses to the digital broad-spectrum color fields, including pairwise two-way interactions between lightness, chroma (colorfulness) -as defined by the L and C values in the CIELCh color space-, and cohort (young vs older adults), as well as the following covariates including: sex, and color stimuli index.

Main effects

 (Intercept)

0.937

0.870–1.009

0.083

 Lightness (L*)ⁱ

0.910

0.900–0.922

 < 0.001

 Chroma (C*)ⁱⁱ

0.975

0.965–0.985

 < 0.001

 Cohort: Young adults

Reference

 Cohort: Older adults

1.106

1.057–1.158

 < 0.001

 Sex: Male

Reference

 Sex: Female

0.994

0.950–1.041

0.808

 Index

0.999

0.995–1.003

0.746

Interaction terms

 Lightness by chroma

1.000

0.996–1.004

0.900

 Lightness by cohort: young adults

0.910

0.899–0.922

0.843

 Lightness by cohort: older adults

0.911

0.899–0.922

 Chroma by cohort: young adults

0.966

0.955–0.976

 < 0.001

 Chroma by cohort: older adults

0.982

0.971–0.992

Random effects

 σ²

0.02

 τ_{00 ID.code}

0.00

 τ_{00 Color.label}

0.00

 ICC

0.32

 N_ID.code

37

 N_Color.label

26

 Observations

782