There has been extensive research on the frequencies, reasons, and factors associated with true and especially false confessions (for overviews, see Gudjonsson 2003; Kassin et al. 2010). However, there is very little legal-psychological literature focusing on other statement behavior from the suspects’ perspective. In many countries, suspects can legally decide for themselves whether or not to make a statement (e.g., § 136 German Code of Criminal Procedure). Under German law, if suspects decide to remain silent, interviewers have to end the interview and are not permitted to ask further questions. If suspects decide to make a statement, they can deny or confess to an accusation. Hence, there are, roughly speaking, three possible statement behaviors that suspects can use in police interviews: remaining silent, confessing, and denying. Differentiating for each statement between interviews for a crime committed (interviewed when guilty) or not committed (interviewed when innocent) results in six interview situations. The present self-report study examines the lifetime prevalences (referring to the total number of participants), conditional probabilities (referring to the total number of innocent or guilty interview situations reported by participants), and reasons for remaining silent, confessing, or denying in relation to the suspects’ reported guilt or innocence status.
Approaches in Research on Suspects’ Statement Behavior
Research on suspect interviews may not only highlight and minimize errors and pitfalls (e.g., Kassin et al. 2010) but also identify and provide practical opportunities and solutions (e.g., Meissner 2021). In the past, one particular focus has been on suspects’ confessions (e.g., Gudjonsson 2003, 2018). These studies often applied behavioral observations of police interviews (e.g., Leo 1996; for an overview, see Moston and Engelberg 2011) or analyses of case files (e.g., Cassell and Hayman 1996). Moston and Engelberg (2011) presented general confession rates for the USA, Great Britain, and Australia ranging from 42 to 76%. However, this range of estimates did not refer exclusively to true confessions, and may also include false confessions (i.e., in observational studies, it is rarely possible to measure the objective or reported status of guilt or innocence). Simply put, this line of research lacks information on the guilt or innocence of the suspects.
Acquittals in retrials can be used to gain information on underlying innocence (e.g., Leuschner et al. 2019). Similarly, several studies use well-known databases (e.g., the Innocence Project 2021, or the National Registry of Exonerations 2021) to examine false confessions more closely (e.g., Appleby et al. 2013). However, this approach can provide only little information on the general prevalence of false confessions. Also, it provides no information on the prevalence of and reasons for true confessions, true/false denials, and remaining silent.
A third research approach is to consult interviewees directly via self-reports which has been frequently applied to study false confessions (e.g., Gudjonsson and Sigurdsson 1994). Self-reports have also been used occasionally to examine true confessions, but almost not at all for the other statement behaviors (see below). Naturally, this approach has the typical limitations of survey studies (e.g., social desirability, memory distortions, intentional false statements). However, self-report studies do provide an opportunity to approximate the underlying guilt or innocence (i.e., reported status of being guilty or innocent), to gain insights into frequency distributions of distinct statement behaviors by real-life suspects, and to learn about their subjective reasons for them. This, in turn, complements studies based on experiments, observations, and case files. Therefore, the present study used self-reports of convicted offenders about their police suspect interviews.
True and False Confessions
Table 1 shows that most self-report studies focus on false confessions. The self-reported prevalence of false confessions by inmates/offenders and forensic patients in Iceland, the USA, and Germany varies between 5.9 and 33%. However, not all studies captured the suspects’ reports on whether they had ever been interviewed; and, if so, whether they were guilty or innocent in these interview situations. Therefore, these prevalence estimates refer to the total population of suspects, including those who have never been interviewed (i.e., remained silent) and those who were guilty. However, innocence is a necessary premise for a false confession. That means, calculating the prevalence of false confessions by considering the whole sample might underestimate the actual risk suspects face in interviews (Volbert et al. 2019). Therefore, another way to estimate the risk of false confessions is to calculate the conditional probability by relating the number of false confessions to the number of innocent interview situations. Following this approach and considering only the suspects who were interviewed when innocent and thus had been at risk of committing a false confession, Volbert et al. (2019) found a conditional probability of 25% (compared to a prevalence of 16% for the overall sample). The main reported reasons for false confessions in self-report studies were police/interviewing pressure, protection of another person/the real offender, and avoidance of police detention/hope for mitigation of sentence (e.g., Redlich et al. 2010; Sigurdsson and Gudjonsson 2001; Volbert et al. 2019). False confessions were reported most frequently for property offenses, traffic violations, and violent offenses.
In comparison to false confessions, Table 1 shows that we found only four self-report studies that examined true confessions among inmates, offenders, or forensic patients. These revealed a prevalence ranging between 28 and 92%. Most commonly reported reasons for true confessions were the perceived proof, a need to clear one’s conscience, police pressure, custodial pressure, and the hope of being released from custody (Gudjonsson et al. 2004a, b; Sigurdsson and Gudjonsson 1994; Volbert et al. 2019). Only one self-report study captured the crime types of true confessions, whereby the highest rates were for serious traffic violations and drug offenses (Sigurdsson and Gudjonsson 1994). Taken together, research on false confessions is steadily growing, but very little is known about the frequencies and reasons for true confessions. Furthermore, in addition to classical calculations of prevalence (specific statement behaviors related to the overall sample of participants), the present study also calculates conditional probabilities (specific statement behaviors related to the total number of innocent or guilty interview situations). This should lead to a better understanding of suspects’ considerations and verbal behaviors.
Denials and Being Silent
Overall, only little research has focused on how often and why suspects deny accusations (for exceptions, see Holmberg and Christianson 2002; Moston and Stephenson 2009). Table 1 shows that we found only two studies examining the frequencies of denials by inmates, offenders, or forensic patients: In the first study, the prevalence of true denials among a sample of forensic patients in Germany was 49%; that of false denials, 31% (Volbert et al. 2019). The second study revealed that the prevalence of true denials among prison inmates in Germany was 51% (Gubi-Kelm et al. 2020). A further study examined the reasons for denials through focus groups and semistructured interviews with sexual offenders (Lord and Willmot 2004). It found that the main reasons for denial included lack of insight, threats to self-esteem and self-image, and fear of negative extrinsic consequences. However, to the best of our knowledge, there is no study contrasting the reasons for denial in suspects who were interviewed when they were guilty versus innocent. In other words, self-report studies did not consider the suspects’ reported status of guilt/innocence when examining the reasons for (true and false) denials.
Research on being silent is very sparse. Table 1 shows only one study examining remaining silent from the suspects’ perspective. The prevalence of remaining silent among forensic patients in Germany was 37% for reported guilty interview situations and 9% for reported innocent interview situations (Volbert et al. 2019). We know of no self-report study examining reasons for remaining silent from the suspects’ perspective. Overall, there are only very few self-report studies with offenders addressing how often and why they deny or remain silent as suspects, and no study examining this in a way that compares innocent and guilty suspects.
The Present Study
The present study examines the lifetime prevalence, conditional probabilities, and reasons for all three statement behaviors (confessions, denials, and being silent) from the perspective of suspects in German police interviews. By taking into account the suspects’ reported guilt and innocence status, it allows us to compare the resulting six distinct interview situations. Based on the previous research presented above, we expected that more suspects would report having confessed truly rather than falsely at least once in their lifetime (Hypothesis 1). We also expected that more suspects would report having denied truthfully than falsely at least once in their lifetime (Hypothesis 2). Moreover, we expected that more suspects would report having remained silent while being interviewed when guilty compared to innocent at least once in their lifetime (Hypothesis 3). These prevalence rates relate to the total number of participants. In addition to this focus on lifetime prevalence, we also examined the probabilities of the three different statement behaviors under the condition of being guilty versus innocent in a given interview situation. Specifically, conditional probabilities refer to the total number of innocent or guilty interview situations reported by participants.
For exploratory purposes, we wanted to examine the reasons for the specific statement behaviors. Here, we expected that the main reasons for a false confession would be to protect another person/the real offender and police/interviewing pressure. Concerning true confessions, we expected that the main reason would be the suspects’ perceptions of the given evidence. We did not formulate any further expectations on the other statement behaviors here due to the lack of relevant studies.