The jury instruction on mental retardation was not inconsistent and was not harmful to the defendant in his trial for capital murder. The jury instruction appropriately tracked the definitions of mental retardation provided by the American Association on Mental Retardation and in Briseno. Extensive testimony was presented by former teachers, employers and psychiatrists and the parties' closing jury arguments made clear that the issue was litigated before the jury. Willams v. State - AP-75,541.