In People v. Cox, the expert's testimony regarding the witness's credibility was deemed inadmissible because the expert's opinion " 'that people in stressful situations sometimes have trouble recalling details is well within the comprehension of the trier of fact.' " Cox, 197 Ill. App. 3d at 1035, 557 N.E.2d at 293-94, quoting People v. Nix, 133 Ill. App. 3d 1054, 1059, 479 N.E.2d 1147, 1151, 89 Ill. Dec. 141 (1985). The Cox court also stated that the testimony was not admissible because its content was well within the range of understanding and knowledge of the average person and, thus, was not a proper subject of expert testimony. Cox, 197 Ill. App. 3d at 1035, 557 N.E.2d at 294.