Understanding the perception of colour and luminance

Humans process luminance information more quickly than colours. The disparity in processing times of the two visual systems has been recognised since the 1950s, but it has remained little understood how coloured objects are perceived clearly even in motion. Haruyuki Kojima at Kanazawa University and Yasuhiro Kawabata at Hokkaido University have now reported experimental evidence of interaction between the achromatic and chromatic systems which provides a useful contribution to understanding how we luminance and colour are perceived.

Previous studies had identified an inverse relationship between the intensity of stimuli and the duration of their perception. The same holds true for the contrast between stimuli and background. Kojima and Kawabata investigated whether the relationship also held for chromatic and achromatic stimuli and the effect of colour contrast.

The researchers varied the luminance of chromatic (red) and achromatic (white) test stimuli, each at the corner of a frame viewed by the test subject. The interval between the stimuli was altered between 0.0 to 159.48 ms. The subject then indicated whether the four stimuli were perceived simultaneously or not. The procedure was then repeated varying the colour contrast of the tests instead of the luminance, and finally using red, green, blue and yellow test stimuli.

The results revealed an ‘‘inverse colour contrast effect’’ in the perceived duration of colour stimuli showed, similar to the ‘‘inverse intensity effect’’ for luminance stimuli. At high luminance contrast the perceived duration of the stimuli were dominated by luminance but at low luminance, the color contrast dominated. The work provides evidence that the independent chromatic and achromatic systems interact but as they point out, “How and where these systems interact to integrate visual information remains an ‘intriguing question’.”

Publication and Affiliation
Haruyuki Kojima1* and Yasuhiro Kawabata2 Perceived duration of chromatic and achromatic light. Vision Research, 53, 21–29 (2012). Link

1. Faculty of Human Sciences, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
2. Department of Psychology, Hokkaido University, Sapporo, Japan

*corresponding author, e-mail address: hkojima@staff.kanazawa-u.ac.jp

ID: 201212A007