Pecola has a deep fascination with Shirley Temple and her blue eyes. But, with her fascination comes a sense of inferiority and self loathing as she is not able to achieve the false white standardness of beauty. This conflict contributes to the overall theme of the novel.
Having suffered at the hands of white society Pecola's father, Cholly, is driven to cruelty and anger. As a result of his rage, drunkenness, and anger, he takes out his rage on his poor daughter and rapes her. Leaving her broken.
As a result of her hatred towards herself and trauma from being raoed by her father, Pecola attempts to cope by believing she has blue eyes. She does this to show herself that she has achieved the white standard of beauty.