JUSTICE STEIGMANN delivered the opinion of the court:

In May 1998, a jury convicted defendant, Michael E. Lind, of aggravated battery of a child (720 ILCS 5/12-4.3(a) (West 1996)), and the trial court later sentenced him to 18 years in prison. Defendant appeals, arguing that (1) the State failed to prove him guilty beyond a reasonable doubt; and (2) the court made certain evidentiary errors. We affirm.

I. BACKGROUND

In July 1996, the State charged defendant with four counts of first degree murder (720 ILCS 5/9-1(a)(1), (a)(2), (a)(3) (West 1996)) and one count of aggravated battery of a child. The jury acquitted defendant of first degree murder and convicted him of aggravated battery of a child and involuntary manslaughter (720 ILCS 5/9-3 (West 1996)). The trial court subsequently set aside those convictions, and the case proceeded to a second trial on the charge of aggravated battery of a child, where the evidence presented showed the following.

Roy Mayfield, a paramedic, testified that around 12:30 p.m. on June 28, 1996, he responded to an emergency call at defendant's trailer. Once inside the trailer, Mayfield saw a woman, Jessie Hayes, performing cardiopulmonary resuscitation (CPR) on A.L., the four-month-old daughter of defendant and defendant's then-wife, Erin Lind. While Jessie continued performing CPR, Mayfield spoke with defendant to obtain medical information about A.L. Defendant told Mayfield that he was feeding A.L. when she suddenly went limp and stopped breathing. Defendant did not tell Mayfield that A.L. had fallen nor did he mention "any type of shaking." Mayfield described defendant's demeanor as "very calm, cool[,] and collected." After gathering A.L.'s medical information, Mayfield performed CPR on A.L. until the ambulance arrived. Once A.L. was placed inside the ambulance, paramedics continued resuscitation efforts.

Jessie, who was defendant's neighbor, testified that on the day of the incident, she saw defendant walk across the street to her trailer and knock on the door. Jessie yelled to defendant to tell him that she and her husband, Brian Hayes, were not inside. Defendant then walked back to the edge of the driveway and told Jessie that A.L. was not breathing and needed help. Jessie went inside defendant's trailer while Brian called an ambulance. A.L. was lying on a stack of blankets fully dressed, including socks on both feet, and she appeared "grayish-blue." Jessie, a certified nursing assistant, "kind of shook" A.L. to get her attention. She then undressed A.L. and began performing CPR. She continued performing CPR until a paramedic arrived and took over. While the paramedic performed CPR, Jessie held A.L.'s head because it was "bobbing back and forth."

Jessie was aware that A.L. suffered from central apnea, a condition in which an individual temporarily stops breathing. She had once heard a nurse explain to defendant and Erin that when A.L. experienced apnea, they should call A.L. by name and "kind of shake her a little bit so you could get her attention."

Paul Haley, A.L.'s maternal grandfather, testified that around 10:05 a.m. on June 28, 1996, he went to defendant's trailer and knocked several times during a 30-minute period. No one responded. Later that day, Haley asked defendant why he had not answered the door earlier that morning, and defendant told Haley that he had been doing laundry at his mother's house. (Defendant's mother testified that defendant could not have been at her home on that morning because he did not have a key to her house.) Haley then asked defendant what had happened to A.L., and defendant initially responded that he had been feeding her when she went limp. Haley then told defendant he "better be straight if something happened" to A.L., and defendant told Haley that he "gave [A.L.] a bath and put lotion on her getting ready to put her socks on her and dropped her and picked her up and dropped her again." Defendant never told Haley that he had shaken A.L.

Lana Schmidt, an emergency room physician, testified that she examined A.L. after the paramedics brought her to the hospital. A.L. was not breathing, and she showed signs of serious brain damage. Schmidt observed "a lot of bleeding" in A.L.'s eyes; such retinal hemorrhage is a sign of "shaken baby syndrome," a term used to describe infants who have experienced a vigorous and violent movement of their heads in a backward and forward motion. Emergency room physicians stabilized A.L., and she was placed in the pediatric intensive care unit, where she later died.

Defendant told Schmidt that he had taken A.L. off the apnea monitor prior to feeding her. After he fed A.L., he noticed that she had "some milk spewing from her mouth and her nose," and defendant picked her up and took her to a neighbor's house to get help. Defendant did not tell Schmidt that A.L. had fallen or that he had shaken A.L., and he specifically denied that A.L. had suffered any impact to her head.

Marilyn Kincaid, an ocular pathologist, testified that shaken baby syndrome results in retinal hemorrhage. Kincaid stated that some physicians and researchers believe that shaking an infant, by itself, will result in retinal hemorrhage, while others believe that an impact injury is also necessary to produce such bleeding. Kincaid examined tissue samples taken from A.L.'s eyes and detected hemorrhage throughout several layers of the retinas, extending to the ora serrata (the anterior edge of the sensory portion of the retina). Kincaid opined that "in this case[,] I felt that the degree of hemorrhage and its extent was absolutely classic for the so-called shaken baby syndrome." She also opined that only a "[v]ery substantial force" could have caused the extent of retinal hemorrhage detected in A.L.'s eyes. Kincaid further stated that the extent of hemorrhage she detected in A.L.'s eyes could occur only in cases of shaken baby syndrome, in older persons suffering from vein occlusion, or in persons involved in very severe motor vehicle accidents. In addition, she opined that an impact injury resulting from a five-foot fall would not cause such retinal hemorrhage.

On cross-examination, Kincaid testified that improperly performed CPR can cause retinal hemorrhaging. She acknowledged that head trauma, followed by vigorous shaking, and then a lengthy period of CPR could combine to create a relatively severe amount of retinal hemorrhaging.

On redirect examination, Kincaid opined that shaking and failed attempts at resuscitation could not have caused the extensive injuries A.L. suffered.

Travis Hindman, a forensic pathologist, testified that on June 30, 1996, he performed an autopsy on A.L. and found that she had suffered a fracture of the occipital bone, which is located on the back of the skull. He stated that it is unusual to find a skull fracture in a four-month-old child because an infant's skull bones are flexible. Hindman opined that the skull fracture, along with the redness he saw on A.L.'s scalp, were caused by "broad surface blunt impact to the skull and the head," which meant that the back of A.L.'s head came into contact with a flat surface. He also noticed that the sutures (the line of union between the skull bones), which usually touch each other, were widely separated. Hindman stated that the "reason for this wide separation of the sutures was an increase in the pressure within the cranial cavity[,] which was expanding [the sutures]." He also found that the sutures were "bulging and blue in color, [which was] indicative of blood beneath them."

Hindman also found a subdural hematoma, "a collection of blood which is found between two membranous layers covering the brain" and a hemorrhage in several areas of the subarachnoid space, which is between the outer layer of the brain and the brain surface. He also detected severe brain swelling.

Following the autopsy, Hindman prepared a report for the coroner, which indicated that A.L.'s cause of death was "brain injury with associated subdural hematoma and subarachnoid hemorrhage due to blunt force trauma to the head." "[P]rimarily to refresh [his] memory about the nature of such injuries and what kinds of forces are incurred," Hindman then reviewed 40 to 50 articles on the subject of falls and the resulting injuries in children. He stated that he commonly reads literature in professional journals prior to authorizing his final autopsy report. Based upon his professional experience, his consultation with another expert regarding A.L.'s injuries, and his reading of the journal articles, Hindman opined that A.L.'s injuries were inconsistent with a fall from five feet onto a carpeted floor.

Hindman issued his autopsy report prior to Kincaid's having completing her report. He had anticipated that his diagnosis might differ from Kincaid's because his autopsy had not included an examination of the interior of A.L.'s eyes. Hindman opined that his findings were consistent with "[s]haken [b]aby [i]mpact [s]yndrome," in which the violent shaking of the infant's head is accompanied by the head's impacting on some surface. When Hindman read Kincaid's report, it did not alter his opinion.

On cross-examination, defense counsel challenged one of the bases of Hindman's opinion that A.L.'s injuries were inconsistent with a five-foot fall onto a carpeted floor. In particular, defense counsel cross-examined Hindman using two articles, which discussed separate studies regarding falls and the resulting injuries in infants and children. In the first study, the author had dropped 15 infant cadavers from a height of three feet onto different surfaces, finding that all 15 cadavers suffered skull fractures. In the other study, the author studied 18 children, with a mean age of 2.4 years, who had fallen from a height of less than three feet and concluded that such falls can be lethal, especially in toddlers. Hindman stated that the two articles did not alter his opinions in this case.

On redirect examination, Hindman testified that a fall from five feet onto a carpeted floor would not explain A.L.'s injuries

"[b]ecause of the eye findings to a large extent[;] the presence of retinal hemorrhage is not typical of a fall alone.

[Retinal hemorrhage is] more typical of the rotational acceleration, deceleration injuries as one would encounter in [s]haken [b]aby [syndrome]."

Erin testified that she and defendant had decided to have a child because they thought it might improve their marriage. Erin stated that having A.L. did make their marriage better "[t]o a certain point," because defendant had not hit her following A.L.'s birth. Erin also stated that defendant was jealous of A.L. and he became upset because Erin spent too much time with her and spent money on her.

Shortly after her birth, A.L. was diagnosed with central apnea, and Erin and defendant received training in using the apnea monitor and performing infant CPR. Erin stated that they were taught to tickle A.L.'s feet or wave her arms lightly to arouse her. However, the instructors told them to "never shake a baby."

At around 9:30 a.m. on June 28, 1996, Erin placed A.L. on a blanket on the floor near defendant's feet and left the trailer. When she returned around 12:30 p.m., defendant came outside and told her A.L. was not breathing. Erin described defendant's demeanor as follows: "[A]t first it sounded like it was no big deal, you know, maybe the dog had an accident on the floor until I heard [A.L.] wasn't breathing." Erin denied that she previously had told a police officer that defendant had run out of the trailer screaming that A.L. was not breathing. Defendant twice told Erin that he had been feeding A.L. when she went limp.

Illinois State Police investigator Richard Weaver testified that on June 28, 1996, he and Cynthia Robbins, a Department of Children and Family Services caseworker, interviewed defendant at the hospital and asked him to explain what had happened to A.L. Defendant told Weaver that he had fed A.L. and placed her on a blanket when "Boom, just like that, she went limp on me and was just staring." Weaver then told defendant that A.L. could not have been injured under those circumstances. Defendant then stated that he did not want to say what really happened because he was afraid that people would think he was a bad father. Weaver again asked defendant what happened to A.L., and defendant responded, "It happened like I told you but I dropped her." Defendant explained that he had dropped A.L. while sitting in a chair attempting to put her socks on her feet. Weaver then told defendant that A.L.'s injuries were too severe to have resulted from such a fall, and defendant stated that he had been standing when A.L. slipped from his hands, fell about five feet, and landed on her head.

Defendant subsequently made a written statement, which was read to the jury. In that statement, defendant stated that he accidentally dropped A.L. from a height of five feet, shook her slightly to get her to breathe, and then shook her harder while she was in a sitting position. A.L. then began to breathe again and defendant held her for 15 or 20 minutes, after which time she "was giggling and playing." About 12:15 p.m., defendant prepared another bottle for A.L., and she drank about 1