Final answer:
William Dobell may have used the Principle of Art proportion by exaggerating and distorting the natural proportions, creating a unique and potentially unnatural portrait, similar to the approach of other artists who twist proportions to convey their artistic vision.
Step-by-step explanation:
When analyzing artwork by William Dobell with regards to the Principle of Art proportion, it is important to understand that artists like Dobell sometimes deliberately distort the natural proportions of the body and face to create a distinctive style or convey a certain message. Proportion in art refers to the relationship between parts within a whole, and artists sometimes manipulate this proportion to achieve a desired effect. For instance, in ancient Greek art, artists used mathematical ratios to achieve lifelike and beautiful proportions. However, in contrast, artists like Rene Magritte in his painting Personal Values used scale and proportion to create surreal and exaggerated scenes, thus intentionally distorting the scale to convey irony. Similarly, William Dobell may have exaggerated and distorted proportions not with the intention of focusing on values to create realism, but to deliver a portrait that is striking and unnatural, leading to a unique interpretation and emotional response from viewers.