Psychology Topics > Forensic Psychology


Forensic psychology is an application of psychology to legal issues and the criminal justice system. In order to understand what forensic psychology encompasses, consider the types of questions forensic psychologists answer in regard to the law and court system.

  • Is a particular individual competent to stand trial?
  • What was the individual's state of mind when he or she committed the act? (e.g. sane versus insane, accidental versus pre-meditated)
  • Was the individual solely responsible for his or her actions or were they being manipulated or threatened to commit the act?
  • Are the witnesses or expert witnesses credible?
  • Is the jury objective or impartial?
  • Are the lawyers acting in their client's best interest?
  • Is anyone involved malingering (that's a fancy word for lying)?
  • Is the sentence/punishment appropriate for the crime and or state of mind of the defendant?
  • Can witness testimony be trusted as fact? Do we accept "recovered memory" as evidence of a crime?
  • In situations where there are several culprits, how we determine who is the most to blame and therefore should get the heaviest sentence or should they all be treated the same?
  • Should children that commit crimes be charged similarly to adults?

Forensic psychologists are different from regular therapists or counselors because they are not as interested in the client-therapist relationship or building rapport. Instead, forensic psychologists attempt to evaluate individuals according to guiding laws and statutes. They are adept at recognizing deception. Forensic psychologists also profile criminals and explain the thought and behavior patterns of particular crimes and groups of people (e.g. serial killers, pedophiles, arsonists and terrorists).

If you're interested in a career in Forensic Psychology, you should definitely check out our interview with Julie, a forensic psychology graduate student. Click here to go to the interview.

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Subfields of Forensic Psychology

Handwriting Analysis
As far back as Aristotle, handwriting has been noted to reflect the personality characteristics of people. Alfred Binet, a psychologist who created intelligence tests, also stated that handwriting styles indicated certain character traits.

Handwriting analysis is used to determine authorship, i.e. who wrote the document or signature. This is helpful in crimes such as forgery, or to determine authenticity of a suicide note. The forensic psychologist also analyzes handwriting as part of their assessment of the individual. Certain handwriting styles are correlated with different mental disorders. Therefore, forensic psychologists use handwriting to profile individuals who have not yet been apprehended. Forensic psychologists also use handwriting and drawings to assess or diagnose victims and/or perpetrators of crimes

Handwriting is not a perfect science per se but helps establish a pattern in the individual. A signature that has thick heavy lines could indicate anger. If a signature is very small in proportion to the other writing, it could indicate insecurity. These are only general examples, however, and true handwriting analysis, also known as graphology, has precise analytic descriptions of each individual letter (cursive or print). It also takes into account the spacing and justification of documents and letters, i.e. does the individual write only on the top half of the paper, is there a disproportionately large indent on either side of the paragraph, etc. Handwriting analysis is actually quite complex.

A person's profile can consist of personality traits, behaviors, and motives behind their behaviors. In forensic psychology, profiling is used to help apprehend criminals by listing possible personality traits and behaviors that were correlated with previously apprehended perpetrators. For example, if it is known that the perpetrator is addicted to heroin, the investigators might look for the suspect in areas of the city known as hang-outs for heroin users. They may also be expecting the perpetrator to attempt a robbery so he or she can get more heroin. This information helps the investigators know where to look and also what to expect when they find the individual. If the police expect to find a perpetrator who is "high" then they will take appropriate precautions.

Along with profiling is the term "racial profiling." This means that police have a heightened awareness or bias of people from a particular race, gender, age group, or social status. Racial profiling is a generalization or stereotype of the types of individuals that tend to commit various crimes. Although it can be true in many cases, investigators need to consider all available suspects to eliminate bias towards one person versus another. Just because the profile of a crime seems to match a past pattern or group of perpetrators does not mean it is a valid assumption for every crime.

Key Figures & Theories

James McKeen Cattell
J. McKeen Cattell was interested in the reliability and validity of witness testimony. He conducted an experiment at Columbia University with a group of students as part of his research. He asked the students to answer several questions, similar to those asked in a court trial, and then asked them to rate how confident they were about their answers. The outcome of the experiment demonstrated a high degree of inaccuracy. This led other psychologists to conduct their own research into the reliability of witness testimony.

Alfred Binet & Lewis Terman
Alfred Binet, a psychologist and lawyer, influenced forensic psychology through his intelligence assessment. Along with Theodore Simon, he developed the Binet-Simon scale for children. The concepts behind this psychometric intelligence scale served as a basis for forensic assessment of intelligence and competency to stand trial. Later, Lewis Terman revised the Binet-Simon intelligence scale to be used to assess intelligence among adults. The result, the Stanford-Binet test, was used to assess candidates applying for law enforcement positions.

Hugo Munsterberg
Hugo Munsterberg wrote a book that was highly influential in the field of forensic psychology called On the Witness Stand. In his book, he discussed how psychological factors could influence the outcome of a trial. He also discussed problems with eye-witness testimony, false confessions and interrogations. At Harvard University, Munsterberg conducted experiments on false testimony, memory, and hypnosis as applied to the legal system.

William Stern
William Stern was another psychologist who studied witness recall. He conducted an experiement in which subjects were instructed to watch an interaction between two students. Afterwards, the subjects were asked to summarize what they saw. Stern discovered that inaccuracies were common, especially when high emotions were present. In another experiment, Stern had students look at a picture for 45 seconds. Then he asked the students to recall what they saw. Stern observed that the longer he waited to ask the subjects to recall the memory of the photograph, the more inaccurate their responses were. Stern also hypothesized that witness could be "led" simply by the wording of questions and inadvertently remember events or details that did not actually occur.

Albert Von Schrenck-Notzing
Albert Von Schrenck-Notzing is important to the field of forensic psychology because he was the first psychologist to testify as an expert witness. As part of his testimony, Schrenck-Notzing explained how the pre-trial publicity of the case could potentially alter witness's testimony. Because of Albert Von Schrenck-Notzing, jury members, witnesses, and other key figures are no longer allowed to view news, or media coverage of court proceedings and investigations for the duration of the trial in which they are involved.

William Marston
William Marston was a student psychologist of Munsterberg that discovered systolic blood pressure had a strong correlation to lying. This discovery led to the creation of the lie detector or polygraph. A polygraph measures and records an individual's physiological responses such as respiration, breathing rhythms, pulse, blood pressure, and skin conductivity. When people lie, their body has a heightened physiological response as compared to when they tell the truth. This physiological response is unique to each person, so an examiner needs to establish a base line before asking significant questions. The base line is established by asking a subject several neutral questions (e.g. "What is your name?" "Where do you live,") and instructing them to lie to other questions while the examiner analyzes their physiological activity. After the base line is established, the examiner asks questions related to the case.

A problem with the polygraph is that it cannot detect deception with 100% accuracy. People can lie and still pass the polygraph if they carefully control their body, i.e. stay calm during questions they have to lie to, and think of something upsetting during control questions (e.g. questions in which the examiner instructs the subject to lie.) The polygraph also cannot distinguish between individuals who are telling the truth, and individuals who believe their account is true even though it may be false. For instance, an individual with schizophrenia could state they are Abraham Lincoln and still pass the polygraph because they truly believe their own delusions.

Marston also contributed to forensic psychology through his expert testimony in the case of Frye vs. United States in 1923. This case was important because it led to the stipulation that a procedure, technique, or assessment must be generally accepted within its field in order to be used as evidence in a criminal investigation.