In Pollock v. Standard Oil Company of California (1967) 256 Cal.App.2d 307, the court found the affidavits of defense counsel and an investigator "that they had interviewed a juror . . ., and that she had said to them that at the time of voir dire she had concealed a bias in favor of the plaintiff" were admissible in determining a motion to vacate the denial of a motion for new trial. (Id. at pp. 308, 310.)