The current research assessed the influence of DNA evidence on beliefs about the guilt of a parent accused of sexually abusing his or her daughter. Participants read scenarios about a custody hearing where a daughter accused her father (or mother) of sexual abuse, under three experimental conditions: there had been no DNA testing, there had been DNA testing, there had been both DNA testing and an expert witness who explained such evidence could be planted.
The most important result was that participants were most likely to agree the accused was guilty in the DNA condition and least likely to believe the accused was guilty in the DNA/expert witness condition. These results suggested that more research was needed to provide information about improper use of DNA testing to reduce decisions that innocent people are guilty or that guilty people are innocent. DNA Evidence: Can it be Used to Convict the Innocent?
Since Freud (1904/1960), we have known that memories of our past experiences may be distorted over time and that memory distortions can be a result of even subtle and unintentional responses from therapists. Bartlett (1932) was the first to demonstrate experimentally that distortions in memories for stories about unfamiliar cultures (as in “War of the Ghosts”) were distorted in a direction consistent with the participant’s own culture.
In the 1970s, Loftus pioneered studies demonstrating inaccuracies in eye-witness testimony, demonstrating, for example, that memory reports of the speed of cars in a filmed accident were higher when participants were asked about the speed when the cars “smashed” than when the “bumped” (Loftus & Palmer, 1974). When allowed, she testified as an expert witness, reporting on the effects of variables such as emotional arousal at the time of the event and the time between an event and identification on accuracy (Loftus, 1979).
Her work has been supported by current DNA evidence that has freed prisoners who had been convicted on the basis of eyewitness testimony (Wells, Memon, & Penrod, 2006). Now that it is well known that DNA evidence has been used to overturn convictions, the current research was an investigation of the possible results of planting DNA evidence. Research since the 1980s has resulted in a body of literature demonstrating the many ways that memories can be planted in people’s minds so that they remember experiencing an event that never occurred.
Much of the research on planting memories was motivated by charges against workers at daycare centers of sexual abuse and satanic rituals (Schacter, 2001). The first accusations were against the owner, members of her family, and others who worked at the McMartin Daycare Center in Los Angeles, after which allegations against other centers “seemed to spread like wildfire” and included charges of eating babies and being taken on spaceships (Schacter, 2001, p. 131).
The McMartin investigation began in 1983 and over six years and many millions of dollars later, there were no convictions (Garven, Wood, Malpass, & Shaw, 1998). When tapes of the children being interviewed became available, we learned of the tactics used in individual interviews lasting over an hour, and why jurors reported they believed the children were being manipulated (Garven, Wood, & Malpass, 2000). Garven et al. (1998) categorized and tested the techniques used by the social workers who interviewed the children.
The categories were asking suggestive questions (e. g. , “Did Miss Peggy take her clothes off,” p. 348), revealing the answers of others (e. g. , “…twenty kids told us about that game,” p. 348), praising any indication of agreement (e. g. , “You’re going to help all these little children just because you’re so smart,” p. 349), insulting children who disagreed (e. g. , “Are you going to be stupid, or are you going to be smart and help us here,” p. 349), and repeating questions until the children “remembered” that an event had occurred.
By the end of most interviews, children reported remembering the events described by the interviewers. The same researchers (Garven et al. , 1998) tested the effects of using such techniques. A week after 3- to 6-year-old children were entertained by a graduate student, 58% of those who were told that “the big kids…said that Manny [the graduate student] did some bad things” (p. 351) “remembered” false negative occurrences (unlike the McMartin children who were interviewed for over an hour, these children were interviewed for less than five minutes).
In a similar study (Garven, Wood, & Malpass, 2000), a week after being entertained by a graduate student, an average of 52% of 5- to 7-year-old children who were given negative and positive feedback about their responses (e. g. , “you’re not doing good,” “you’re doing excellent now,” p. 41) agreed with false plausible and implausible allegations. Most of these children agreed with the same allegations a week later when they received no feedback, a finding interpreted as evidence that the children formed lasting memories, as opposed to having been led to respond in ways that pleased the interviewer.