Comparing Judgments of Visual Clarity and Spatial Brightness through an Analysis of Studies Using the Category Rating Procedure

Abstract

This article discusses spatial brightness and visual clarity to question whether these are similar or different phenomena of visual perception. A review of the descriptions reported in past articles suggests that some researchers consider spatial brightness and visual clarity to be different, although this is not a universal opinion. In contrast, analyses of the results of brightness and clarity judgments given by naïve test participants to lighting of different spectral power distribution in previous work suggests that similar judgments are given for brightness and clarity when the meanings of these items are undefined in the test procedure and this is the more frequent situation. This review demonstrates the need for care in defining and interpreting category rating scales.

Keywords:

• Visual clarity
• brightness
• spatial brightness
• category rating
• experimental design.