Beware an optical illusion's effect on your paintings and drawings

Your eyes are deceiving you! In 1995, an optical illusion published by Edward H. Adelson, a Professor of Vision Science at MIT, drew attention to the fact that our eyes perceive how light or dark an object is based on the lightness or darkness of its neighbouring objects. If you are seeing the illusion below for the first time, you would probably call me crazy if I told you that Square A and Square B have the exact same tonal properties. But they actually do as the subsequent picture shows.

The checker shadow illusion as published by Edward H. Adelson, Professor of Vision Science

When cut out and placed next to each other, the squares A and B are found to be of the same shade

This illusion has implications on our artwork be it paintings or drawings. In essence, the checker shadow illusion highlights our visual system's weakness at being a physical light meter. I believe the same principle is roughly at work when a colour that we paint on our miniatures can sometimes look noticeably different based on which other colours are surrounding it. To illustrate my point, I made a skin tone comparison between the Nocturna Models Le Petit Chaperon and Akelarre Enchantment figures. At first glance, one can arguably assume that the former has a slightly brighter skin tone.   

A light skin tone on the finished Nocturna Models Le Petit Chaperon

A seemingly duskier skin tone on the work-in-progress Akelarre Enchantment

However, upon closer inspection - and when the surrounding colours are removed as to negate their influence - it would seem that the latter i.e. work-in-progress Enchantment figure is the one with the much lighter skin tone. Her skin's seemingly dusky undertones are more apparent when viewed next to her light turquoise dress. Similarly, Le Petit's skin tone is made lighter by the darker contrasts of her red cloak and blue corset. As control, both figures were photographed under the same condition.

Putting both the Nocturna Models miniatures side-by-side for a skin tone comparison

Comparison between skin tones sans surrounding colours

Such optical illusions are more noticeable when drawing with graphite pencils because we are dealing with a gradation of only two colours namely black, white and the resulting grey hues in between. Looking closely at my drawing below, you might notice the highlights/reflected light on the ala (or wing) of Park Joo-Mi's nose looks as bright as the highlights on her left cheekbone. But as the following edited picture shows; this is not the case at all. The illusion is caused by the wing of the nose being located next to the dark shades of the nostril which makes the reflected light look much brighter than it really is. And this illusion caused an error on my part: Highlights on the bridge of her nose have the same tonal value as the wing of the nose when the former should have been brighter. Inconsistencies such as this are among the kinks that I need to iron out before I can improve further.

Finished portrait drawing of Park Joo-Mi

Optical illusion showing reflected light on the ala (or wing) of the nose is darker than it actually looks

My suspicion of this phenomena was first confirmed in a National Geographic Channel show called Brain Games and reaffirmed when I came across this brilliant YouTube video by JD Hilberry. I would strongly advise you watch both sources to better understand how this optical illusion can effect your paintings and drawings. Just being aware of the problem has been a real eye opener for me. Hopefully, this post can bring a similar awareness to those of you who do not yet know, or those that do but just can't quite put your finger on what you may already instinctively know. Either way, may this little bit of information help you as much as it has helped me in my quest to create better art.