On this woman's back, in the neck area, is actually a piece of clothing. Yet, the appearance of this part of clothing has sufficient correspondence to the visual characteristics of a monkey, such that a viewer could experience the visual illusion of a monkey. After that, the viewer might think of the idea of "a monkey on her back." This is another example of an illusion that functions to create an allusion.
According to the Oxford English Dictionary, as early as 1865, the term "monkey on your back" meant having a burden. That idea is no less real than the idea suggested by this woman's dress being snagged by the cotton plant. The two ideas "monkey on her back" and "stuck in the cotton fields" appear to be making the same point. Look more. This woman's hands are not picking cotton, and her bag may have less cotton than the other woman's basket. Notice also, she appears to be looking beyond the cotton field, out into the distance, perhaps dreaming of some other place or situation where she would rather be.
