Psychologists have identified a number of key investigative tasks where psychology is particularly relevant. One of these tasks relates to the collection and evaluation of investigative information­information that is often obtained from suspects through police interrogations. Another task relates to investigative decision making, especially decisions that require an in-depth understanding of criminal behaviour.


Police Interrogation: A process whereby the police interview a suspect for the purpose of gathering evidence and obtaining a confession

Confession evidence is often viewed as a prosecutor's most potent weapon, and police officers will often go to great lengths to secure such evidence. People who confess to a crime are more likely to be prosecuted and convicted than those who do not.

In the past, physically coercive tactics were often used to extract confessions from suspects. Although these overt acts of physical coercion have become much less frequent with time, some people have argued that these tactics have been replaced with more subtle, psychologically based interrogation techniques, such as lying about evidence, promising lenient treatment, and implying threats to loved ones. Leading authorities in the field of interrogation training openly state that, because offenders are typically reluctant to confess, they must often be tricked into doing so.


Police officers often receive specialized training in how to extract confessions from suspects. This training differs from North America to Great Britain.

Reid model: A nine-step model of interrogation used frequently in North America to extract confessions from suspects

Although the Reid model of interrogation can take different forms, it generally consists of a three part process:

  • The first stage of the process is to gather evidence related to the crime and to interview witnesses and victims.
  • The second stage is to conduct a non-accusatorial interview of the suspect to assess any evidence of deception (i.e., to determine whether the suspect is lying when he or she claims to be innocent).
  • The third stage is to conduct an accusatorial interrogation of the suspect if he or she is perceived to be guilty in which a nine-step procedure is implemented, with the primary objective being to secure a confession from the suspect.

This nine-step procedure in stage three generally consists of the following steps:

  1. Suspect is immediately confronted with his or her guilt. If the police do not have any evidence
  2. against the suspect at this time, the interrogator can hide this fact and, if necessary, imply that such evidence exists.
  3. Psychological themes are then developed that allow the suspect to rationalize or excuse the crime. For example, a murderer may be told that the interrogators understand why he committed the crime and that the crime was even justified (e.g., given that the victim was a known criminal “who had it coming”)
  4. The interrogator interrupts any statements of denial by the suspect to ensure the suspect does not get the upper hand in the interrogation.
  5. The interrogator overcomes the suspect's objections to the charges.
  6. If the suspect becomes withdrawn, the interrogator ensures that he or she has the suspect's attention and that the suspect does not tune out of the interrogation. A range of techniques can be used for this purpose, such as reducing the psychological distance between the interrogator and the suspect (e.g., by physically moving closer to the suspect).
  7. The interrogator exhibits sympathy and understanding, and the suspect is urged to come clean (e.g., by appealing to the suspect's sense of decency,).
  8. The suspect is offered explanations for the crime, which makes self-incrimination easier to achieve. For example, rather than the suspect being involved in an intentional homicide, which would carry a very severe penalty, the interrogator may suggest to a murder suspect that the crime he or she committed was accidental (e.g., the result of an argument that simply went wrong).
  9. Once the suspect accepts responsibility for the crime, typically by agreeing with one of the alternative explanations, the interrogator develops this admission into a full confession for the crime in question.
  10. Finally, the interrogator gets the suspect to write and sign a full confession.

In addition to the techniques included in these nine steps, Inbau et al. (2004) provided many other suggestions for how to effectively interrogate suspects. These suggestions include things such as using a plainly decorated interrogation room to avoid distractions, having the evidence folder in your hand when beginning the interrogation, and making sure that the suspect is alone in the interrogation suite prior to the interrogator entering the room.

These sorts of interrogation techniques can be broken down into two general categories:

Minimization Techniques: Soft sell tactics used by police interrogators that are designed to lull the suspect into a false sense of security (sympathy, excuses, justification)

Maximization Techniques: Scare tactics used by police interrogators that are designed to intimidate suspect believed to be guilty (exaggerating seriousness of the crime, making false claims about evidence police supposedly have, referring to a non-existent eyewitness)

There is also the Mr. Big Technique where in Canada, police officers take a suspect and try to involve them in a fake gang and then get them to confess to their crime committed before entering the gang as insurance to “Mr. Big” the boss in case the suspect ever turned on him. This can elicit the needed confession without entrapment and lead to a conviction.


Currently, it is not possible to say with any degree of confidence how often police officers in North America use Reid interrogation techniques, but studies are beginning to shed some light on this issue.

Kassin et al. (2007) recently conducted a survey of 631 police investigators about their interrogation practices. They had the officers rate how often they used different types of interrogation techniques. The results of the survey indicated that many of the techniques included in the Reid model of interrogation were used in actual police interrogations, although the frequency of use varied across techniques. Given that Kassin et al.'s (2007) results were based on interrogators' self-reported behaviour, there is, of course, the chance that their responses were biased.

For instance, interrogators almost always used techniques such as isolating suspects from friends and family and trying to establish rapport with suspects to gain their trust.

Other common but less frequently used techniques included confronting suspects with their guilt and appealing to their self-interest.

Less common still, but sometimes used techniques included providing justifications for the crime and implying or pretending to have evidence.

Very rare techniques were instances of threatening the suspect with consequences for not cooperating and physically intimidating the suspect.

King and Snook (2009) recently conducted a more objective analysis of police interrogations. They obtained 44 videotaped interrogations conducted by Canadian police officers and coded the various techniques the interrogators used. Like Kassin et ai.'s (2007) survey, the results indicate that the sampled interrogators did not strictly adhere to the core components of the Reid model of interrogation, many of which are outlined above, although some of the guidelines suggested by Inbau et aL (2004) were regularly observed. In addition, very few coercive strategies were observed in the interrogations, although a reasonable number of suspects were not read their rights to silence and legal counsel (although this could have occurred before the videotaping of the interrogation).

Interestingly, the number of Reid techniques used by the interrogators in this study did relate to interrogation outcomes, with more confessions being given when interrogations contained a greater proportion of Reid techniques. However, as King and Snook (2009) stated, this result does not necessarily prove the effectiveness of the Reid model, since there are many possible explanations for this finding (e.g., an interrogator could expend more effort when there is clearer evidence of a suspect's guilt and the number of interrogation techniques they use could reflect this effort).


Because many police officers are trained to use the Reid model of interrogation, especially in North America, it has been the subject of much research. This research indicates that the technique is associated with a number of potential problems.

Three problems in particular deserve our attention. The first two relate to the ability of investigators to detect deception and to the biases that may result when an interrogator believes, perhaps incorrectly, that a suspect is guilty. The third problem has to do with the coercive and/or suggestive nature of certain interrogation practices and the possibility that these practices will result in various types of false confessions.

Detecting Deception

Deception Detection: Detecting when someone is being deceptive

The issue of whether investigators are effective deception detectors is an important one, especially when using the Reid model of interrogation, because the actual interrogation of a suspect begins only after an initial interview has allowed the interrogator to determine whether the suspect is guilty. The decision to commence a full-blown police interrogation, therefore, relies on an accurate assessment of whether the suspect is being deceptive when he or she claims to be innocent.

As a result of this inability to accurately detect deception, it seems likely that the decision to interrogate a suspect when using the Reid model of interrogation will often be based on an incorrect determination that the suspect is guilty.

In the United States there is a safeguard for people who are being transitioned into the interrogation phase. These are the Miranda Rights. In Canada, the suspects' rights are included in the Charter of Rights and Freedoms.

*In both countries, it is only when suspects knowingly and voluntarily waive these rights that their statements can be used as evidence against them.*

One significant problem is that many individuals do not understand their rights when they are presented to them. Consider a recent Canadian study by Eastwood and Snook (2010). They sampled 56 undergraduate students, nearly half whom were enrolled in a police recruitment program. Each participant was presented with the two legal cautions that are supposed to be presented to suspects in Canada—the right to silence and the right to legal counsel —first in verbal format and then in written format, one element at a time.

  • The right to silence includes multiple elements, such as: (1) You need not say anything, (2) you have nothing to hope from any promise or favour, and (3) you have nothing to fear from any threat)

After each type of presentation, participants recorded their understanding of the caution and rated how confident they were with their answer. The researchers coded these responses for degree of accuracy, with points being provided for each element of the caution that the participants correctly understood.

In general, participants had difficulty understanding each of the cautions, particularly certain elements, but presenting the cautions in written format, one element at a time, allowed for a greater degree of comprehension. Importantly, self-reported confidence was not a good predictor of a participant's degree of comprehension, and demographic variables, such as group status (student versus police recruit), were not related to comprehension.

“Canadians facing an investigative interview situation will not fully comprehend their rights, and therefore are unable to make a fully informed decision regarding whether or not they should waive their rights” - This was the conclusion of the study.

Certain populations seem particularly vulnerable when it comes to misunderstanding their legal rights, including young people and those with impaired intellectual capacity. For example, Canadian high school students exhibit very low levels of comprehension when presented with Canadian youth waivers in oral format. In fact, in this particular study, high school students understood less than half the material (approximately 40%) contained in the waiver. In part this is because Canadian youth waivers are written in a relatively complex fashion (e.g., they are lengthy and contain difficult and infrequently used words.)

Investigator Bias

Investigator Bias: Bias that can result when police officers enter an interrogation setting already believing that the suspect is guilty

The problem here is that when people form a belief about something before they enter a situation, they often unknowingly seek out and interpret information in that situation in a way that verifies their initial belief.

In a mock interrogation study, the researchers had students act as interrogators or suspects. Some of the interrogators were led to believe that the suspect was guilty of a mock crime (finding a hidden key and stealing $100 from a locked cabinet) while others were led to believe that the suspect was innocent. In reality, some of the suspects were guilty of the mock crime whereas others were innocent. Interrogators were instructed to devise an interrogation strategy to use on the suspects, and the suspects were told to deny any involvement in the crime and to convince the interrogator of their innocence. The interrogation was taped, and a group of neutral observers then listened to the recording and were asked questions about the interrogator and the suspect.

A number of important results emerged from this study:

  1. Interrogators with guilty expectations asked more questions that indicated their belief the suspect's guilt. For example, they would ask, ”How did you find the key that was hidden behind the DVD player?” instead of “do you know anything about the key that was hidden behind the DVD player?”
  2. Interrogators with guilty expectations used a higher frequency of interrogation techniques compared with interrogators with innocent expectations, especially at the outset of the interrogation.
  3. Interrogators with guilty expectations judged more suspects to be guilty, regardless of whether the suspect was actually guilty
  4. Interrogators indicated that they exerted more pressure on suspects to confess when, unbeknownst to them, the suspect was innocent.
  5. Suspects had fairly accurate perceptions of interrogator behaviour (i.e., innocent suspects believed their interrogators were exerting more pressure).
  6. Neutral observers viewed interrogators with guilty expectations as more coercive, especially against innocent suspects, and they viewed suspects in the guilty expectation condition as more defensive.

In sum, these findings indicate that investigative biases led to coercive interrogations that caused suspects to appear guiltier to both the interrogator and neutral observers, even when the suspect had committed no crime.


The decision to admit confession evidence into court rests on the shoulders of the trial judge. Within North America, the key issues a judge must consider when faced with a questionable confession are whether the confession was made voluntarily and whether the defendant was competent when he or she provided the confession. The reason for using these criteria is that involuntary confessions and confessions provided when a person's mind is unstable are more likely to be unreliable.

What is meant by ‘voluntary and “competent” is not always clear, which is why debate continues over the issue. What does seem clear, however, is that confessions resulting from overt forms of coercion will not be admitted in North American courts. Conversely, confessions that result from more subtle forms of psychological coercion are regularly admitted into court, in both Canada and the United States.

For example, in the Canadian case of R. v. Oickle (2000), Richard Oickle confessed to seven counts of arson occurring in and around Waterville, Nova Scotia, between 1994 and 1995. The confession was obtained after a police interrogation in which several questionable interrogation techniques were used. These tactics included exaggerating the infallibility of a polygraph exam, implying that psychiatric help would be provided if the defendant confessed, minimizing the seriousness of the crimes, and suggesting that a confession would spare Oickle's girlfriend from having to undergo a stressful interrogation. After considering whether Oickle's confession was voluntarily given, the trial judge deemed the confession admissible and convicted him on all counts. The Court of Appeal subsequently deemed the confession evidence inadmissible and entered an acquittal. On appeal before the Supreme Court of Canada, a ruling was handed down, which stated that Oickle's confession was properly admitted by the trial judge, and therefore his conviction should stand, despite the interrogation techniques employed by the police.

Box 3.2 Cases in Forensic Psychology

When the Police Go Too Far: R. v. Hoilett (1999)

Hoilett was under the influence of alcohol and cocaine and was taken into police custody late at night. He was placed in a cell and his clothing was removed and taken for evidence. He was left naked in his cell. He was then given some light clothes, no underwear and shoes that didn't fit. He was taken into interrogation at 3am and the interrogators had to continuously ask if he was awake. He was believed to not be impaired by the police and thus when he made an incriminating statement it was considered voluntary and admissible in court. He was then convicted on one count of sexual assault. The Court of Appeal made claim that Hoillet was not competent at the time of interrogation. As a result the Ontario Court of Appeals reversed the decision of the trial judge and ruled that the statement Hoilett made was involuntary and thus a new trial was ordered to be held.


Because of the potential problems that can result from using coercive interrogation tactics, police agencies in several countries have recently introduced changes to their procedures. Perhaps more than anywhere else, these changes have been most obvious in England and Wales, where courts have restricted the use of many techniques found in the Reid model of interrogation.

Currently, these agencies use the so-called PEACE model to guide their interrogations.

PEACE is an acronym for:

  • Planning and Preparation
  • Engage and Explain
  • Account
  • Closure
  • Evaluation

This model gives an inquisitorial framework within which to conduct police interrogations (compared with the accusatorial framework used in the Reid model) and is based on an interview method known as conversation management, which encourages information gathering more than securing a confession.

In fact, police agencies in England and Wales have all but abandoned the term interrogation in favour of investigative interviewing to get away from the negative connotations associated with North American-style interrogation practices.

Recently, a call has been made by Canadian researchers to replace current interrogation techniques in Canada with the PEACE model. Dr. Brent Snook is one of the key people leading this charge.

Dr. Brent Snook is an associate professor in psychology at Memorial University of Newfoundland. He holds a PhD in psychology from the University of Liverpool in the United Kingdom. His research pertains to the study of human behaviour within the criminal justice system, and he aims to advance scientific literacy within policing and enhance the administration of justice. His research explores the mental strategies that people operating in the criminal justice system use to make decisions and attempts to determine when and why their strategies work well. He found that simplifying the language used in police cautions, and explaining the rights multiple times, can improve people's understanding of their rights. He has carried out important research that has challenged the legitimacy of interrogation techniques, such as the Reid model described earlier in this chapter. This research has led him to explore other potential options for suspect interrogations, including the PEACE model of investigative interviewing.

While it is still too early to know if the PEACE model of interviewing will be incorporated into Canadian policing, some change is occurring. At least one Canadian police force (the Royal Newfoundland Constabulary) is showing a commitment to reform police interrogation practices.


False Confession: A confession that is either intentionally fabricated or is not based on actual knowledge of the facts that form its content

Retracted Confession: A confession that the confessor later declares to be false

Disputed Confession: A confession that is later disputed at trial

The Frequency of False Confessions

Most researchers readily admit that no one knows how frequently false confessions are made. One problem is that it can be difficult to determine whether a confession is actually false. The fact that a confession is coerced does not mean the confession is false, just as a conviction based on confession evidence does not mean the confession is true.

One approach that has become increasingly popular for estimating the false confession rate is to examine the causes of wrongful convictions. Regardless of the exact number of false confessions that occur, most researchers believe there are enough cases to treat the issue very seriously.

Different Types of False Confessions

Voluntary False Confession: A false confession that is provided without any elicitation from the police

Coerced-Compliant False Confession: A confession that results from a desire to escape a coercive interrogation environment or gain a benefit promised by the police

Coerced-Internalized False Confession: A confession that results from suggestive interrogation techniques, whereby the confessor actually comes to believe he or she committed the crime

Perhaps the most frequently cited case of a coerced-internalized false confession is the Paul Ingram case. In 1988 Paul Ingram was accused by his two adult daughters of committing crimes against them, crimes that included sexual assault, rape, and satanic ritual abuse. As if some of these allegations were not strange enough, Ingram confessed to the crimes after initially being adamant he had never committed them. In addition, he was eventually able to recall the crimes in vivid detail despite originally claiming he could not remember ever abusing his daughters. Ingram ended up pleading guilty to six counts of rape and was sentenced to 20 years in prison. In prison, Ingram came to believe he was not guilty of the crimes he confessed to. After having initial appeals rejected, Ingram was released from prison on April 5, 2003.

Studying False Confessions in the Lab

Researchers have attempted to develop innovative laboratory paradigms that allow them to study the processes that may cause false confessions to occur without putting their participants at risk.

In one classic study, Kassin and Kiechel (1996) tested whether individuals would confess to a “crime” they did not commit. They had participants take part in what they thought was a reaction time study. A co-conspirator read a list of letters out loud to a participant who had to type these letters into a computer. However, before each session began, the participant was warned that if he or she hit the ALT key on the keyboard while computer automatically crashed, which brought the head researcher into the lab with accusations that the participant had hit the key.

Kassin and Kiechel were specifically interested in how two factors would affect participant reactions to the allegations. Participant vulnerability (defined as the participant's certainty concerning his or her own innocence) was manipulated by varying the speed that participants had to type. In the “not vulnerable” condition, letters were read at a rate of 43 letters per minute; in the “vulnerable” condition, letters were read at a rate of 67 letters per minute. The researchers also varied whether false evidence was presented. In the “no false evidence” condition, the co-conspirator stated she did not see what happened; in the “false evidence” condition, she stated she saw the participant hit the ALT key.

Compliance: A tendency to go along with demands made by people perceived to be in authority. Even though the person may not agree with them

Internalization: The acceptance of guilt for an act, even if the person did not actually commit the act

Confabulation: The reporting of events that never actually occurred

To measure the degree to which participants exhibited compliance with the allegations, the researchers presented each participant with a written confession and recorded how many participants signed it.

To measure the degree to which participants internalized their confession, the researchers recorded comments made by participants to another co-conspirator outside the lab who asked them what had happened. If the participant accepted blame for the crime, he or she was recorded as exhibiting internalization.

To measure the degree to which participants made up details to fit with their confession, known as confabulation, the researchers brought the participant back into the lab, read the list of letters again, and asked the participant to try to reconstruct where things had gone wrong.

  • Many participants accepted responsibility for the crime despite the fact that they were innocent, particularly the vulnerable participants presented with false evidence.
  • Many participants also internalized their confession. Again, this was especially true for vulnerable participants presented with false evidence.
  • Vulnerable participants presented with false evidence were once again found to be particularly susceptible to confabulation.

The Consequences of Falsely Confessing

False confessions cause problems for both the person making the false confession and the police agencies tasked with investigating the crime. The obvious problem that the person making the false confession faces is that, if the confession is admitted in court, the jury could convict the suspect for a crime he or she did not commit.

Recent laboratory studies have shown that jurors might be likely to convict a suspect based on confession evidence even when the jurors are aware that the suspect's confession resulted from a coercive interrogation.

Unfortunately, recent research has also suggested that many genuine false confessions are likely to be viewed as evidence of guilt by potential jurors. Appleby, Hasel, and Kassin (2013) highlighted at least three reasons why jurors are unlikely to identify confessions by innocent people as false (and thus use them as the basis for guilty verdicts).

  1. Jurors are unlikely to believe that a person would be willing to make statements that counter self-interest, even in the context of a police interrogation
  2. Due to problems with deception detection, people are unable to accurately distinguish between true and false confessions
  3. False confessions are often very similar to true confessions with respect to their form and content
A second, and less commonly recognized, consequence of false confessions involves the consequences for the police and, therefore, the public. When somebody makes a false confession, the police are diverted down a false trail that may waste valuable time, time that they could have used to identify and apprehend the real offender.
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