The other constancies

My two previous  the Posts provided links to Chapter 12, “Local colour interactions” and Chapter 13, “Colour constancy”, from my book “What Scientists can Learn from Artists”. This Post provides a link to Chapter 15, “The other constancies”. Below the two images you will find an edited version of the “Introduction” to this chapter. As with other Posts, if you find that the subject matter interest you, you can click on the link below to the .PDF version of the chapter as a whole. The images illustrate two of the visual perceptual problems with which artists have had to come to terms.

Cézanne read Helmholtz and took the view that perceived reality is different from the measured reality that his predecessors sought to depict. When he tipped up landscapes and the tops of pots and vases it was because he believed that he was painting what he saw, even if he had to cheat to do so.


Introductory to Chapter 15

Colour constancy is by no means the only constancy of visual perception. There are many other constancies and all are fundamental to the ability of the eye-brain to make practical use of visually acquired information. Paradoxically, although their name suggests stability, they are responsible for the veritable “shifting sands of appearance” which, in its various guises, constitutes one of the main problems for artists seeking to obtain accuracy in drawings or paintings from observation. This is because they ensure that, when we look separately at any two similar features of appearances whether they be whole objects, parts of objects, sections of contour or colours, there is a very strong tendency to see them as being more similar to one another than objective measurement would dictate – often a great deal more so. Our visual systems upset the measured parameters of external relationship by relentlessly forcing them towards normative dimensions and values. As a result, the constancies involve enlarging and diminishing, squashing and stretching, revolving, darkening and lightening and modifying colour. Any list of the constancies of particular interest to the artist should certainly include (a) size constancy, (b) shape constancy, (c) orientation constancy (d) lightness constancy and (e) colour constancy.






Related chapters from “What Scientists can Learn from Artists”

Other Posts on colour and light in painting:

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3 thoughts on “The other constancies”

  1. Thank you for this post Francis. Few teachers, in my experience, explain the constancies and certainly not in the depth that you do. This is all hugely useful to anyone seriously interested in learning about the dynamics of painting and drawing.

    1. oui, c’est extraordinaire ton enseignement, il n’y a aucun doute, merci Francis, je met sur facebook tes posts pas tous, qu’est ce que tu en penses ? j’ai beaucoup de copines english speaking qui peignent à Aignan aussi.

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