In Fielder v. State, 756 S.W.2d 309 (Tex. Crim. App. 1988), the Court of Criminal Appeals held that expert testimony about the psychological effects of marital abuse is relevant to a defendant's claim of self-defense because the expert testimony could assist the jury in its decision concerning whether the defendant reasonably believed that deadly force was immediately necessary. Id. at 318-20. The court found that expert testimony was relevant because the average lay person "has no basis for understanding the conduct of a woman who endures an abusive relationship." Id. at 321.