What is the test for giving a jury cautionary instruction in a sexual assault case?

As stated in People v. McGhee (1954) 123 Cal.App.2d 542, 544, 266 P.2d 874, 876: 'The reasons given for requiring the cautionary instruction in cases involving sex-offenses, particularly where the testimony of the complaining witness is uncorroborated, as here, are (1) the fact that the only available direct witnesses are ordinarily the complaining witness and the defendant, and hence the charge is easy to make and difficult to disprove; (2) cases involving sex-crimes generally arouse passion and prejudice in the minds of decedent people, including jurors; (3) the ease with which the charge can be made to satisfy spite, vengeance, vindictiveness and other base motives. [Citations.]'

The issue on this appeal is whether the error in the court failing to give the cautionary instruction, sua sponte, is prejudicial. That such is not necessarily prejudicial is shown by a number of cases. In People v. Nye, supra, 38 Cal.2d 34, 237 P.2d 1, the error was held nonprejudicial under the circumstances of that case. There the court said (p. 40, 237 P.2d p. 5): 'The circumstances of each case determine whether failure to give the instruction was prejudicial.'