What is the impact of sexual abuse on a child?

observed in children who have experienced sexual abuse: (1) secrecy; (2) helplessness; (3) entrapment and accommodation; (4) delayed disclosure; and (5) retraction. (See People v. Bowker (1988) 203 Cal.App.3d 385, 389.) "[E]xpert testimony on the common reactions of child molestation victims is not admissible to prove that the complaining witness has in fact been sexually abused; it is admissible to rehabilitate such witness's credibility when the defendant suggests that the child's conduct after the incident--e.g., a delay in reporting--is inconsistent with his or her testimony claiming molestation. [Citations.] 'Such expert testimony is needed to disabuse jurors of commonly held misconceptions about child sexual abuse, and to explain the emotional antecedents of abused children's seemingly self-impeaching behavior. [] The great majority of courts approve such expert rebuttal testimony.' [Citation.]" (People v. McAlpin (1991) 53 Cal.3d 1289, 1300-1301, fn. omitted.)