Definition
The Farnsworth-Munsell 100 Hue Test (FM100) is the gold standard for measuring hue discrimination ability. The test consists of 85 movable colour caps, divided over four trays, spanning the entire hue circle. The subject arranges the caps in order of perceived colour difference.
Background
Dean Farnsworth developed the FM100 in 1943 for the U.S. Navy to screen personnel for colour perception. The test distinguishes itself from binary screening methods (such as Ishihara) by producing a continuous discrimination profile: from superior to severely reduced, with insight into the specific hue zone where errors occur.
The scoring system is based on the Total Error Score (TES): per cap the deviation from the correct order is calculated. The lower the TES, the better the hue discrimination. The score interpretation follows the norm values from Kinnear & Sahraie (2002):
- Superior: TES 0–16
- Normal: TES 20–100 (age-dependent)
- Reduced: TES > 100
Relevance to ColorAptitude™
ColorAptitude™ digitises the FM100 principle: in the Hue Ordering Diagnostic the user arranges digital colour stimuli across the hue circle. The scoring is based on the same error vector logic as the physical FM100, with stimulus spacing computed in the OKLCH colour space (Ottosson, 2020) for perceptual uniformity.
Because ColorAptitude™ works fully digitally, the limitations of the physical FM100 are eliminated: no fading of caps, standardised illumination via screen calibration, and instant result calculation.