How have courts treated the opinion of an expert on provocation in a criminal case?

concluded that because the expert's testimony was that "defendant's childhood could have affected defendant's behavior as a an adult, not how defendant's specific childhood experiences influenced the crimes he committed as a adult," the opinion was neither complex nor technical and addressed a matter readily understood by the jury. (Id. at p. 427; People v. Czahara (1988) 203 Cal.App.3d 1468, 1478 [affirming trial court's exclusion of expert testimony about whether provocation was sufficient to cause a reasonable person to respond violently: "the adequacy of provocation is not a subject sufficiently beyond common experience that the opinion of an expert would assist the trier of fact"].)