In People v. Johnson (1992) 3 Cal.4th 1183, the appellant requested that the jury be given this instruction: "'Was the witness's memory affected by intervening time and events? Memory tends to fade over time, and studies show that a witness may subconsciously incorporate into her memory information from other sources.'" (Ibid.) The court explained that "the requested instruction was argumentative, in that it invited the jury to draw inferences favorable to the defendant from specified items of evidence on a disputed question of fact." (Ibid.) Further, the court noted that "the concept that post-event information could contaminate a witness's identification was adequately covered by other instructions." (Ibid.) Further, the California Supreme Court held that CALJIC No. 2.92 or a comparable instruction is appropriate "when requested in a case in which identification is a crucial issue and there is no substantial corroborative evidence." (People v. Wright (1988) 45 Cal.3d 1126, 1144 (Wright).) In People v. Johnson, supra, 3 Cal.4th 1183, the court rejected a claim that the trial court erred when it instructed the jury to consider the degree to which the witness was certain. (Id. at p. 1231.)