During the transition period from infant to toddler, core gender identity is solidified. The child can look at a picture and clearly differentiate sexual differences. She or he can distinguish between male and female by means of the differences in hair and clothing. The child continues to be able to identify body parts, and especially areas responsible for excretion. The child also develops distinct pride and pleasure in his or her own body, sometimes specifically in the genital area. Pleasurable genital self-stimulation also enhances this self-satisfaction. At about 21 months, the child can refer to the self by her or his own name, an event pivotal in the emergence of identity. By 2 years of age, the child is able to categorize people into boy and girl and has some awareness of the anatomic differences if she or he has had an opportunity to view them.