What is Forensic Psychology?

Forensic Psychology is the application of the science and profession of psychology to questions and issues relating to law and the legal system. The word "forensic" comes from the Latin word "forensis," meaning "of the forum," where the law courts of ancient Rome were held.

Many people confuse Forensic Psychology with forensic science. Although the two are closely related, there are many differences. The primary difference is that forensic psychologists delve into the vast psychological perspectives and apply them to criminal justice system.

Additionally, forensic psychologists frequently deal with legal issues, such as public policies, new laws, competency, and also whether a defendant was insane at the time a crime occurred. All of these issues weave together psychology and law topics and are essential to the discipline of Forensic Psychology. Forensic Psychology knowledge is used in various forms, such as in treating mentally ill offenders, consulting with attorneys (e.g., on picking a jury), analyzing a criminal's mind and intent, and practicing within the civil arena in areas such as child custody evaluations.

The key tools for a forensic psychological evaluation are objective psychological assessment instruments.

What is objective psychological assessment and why is it important?

Objective psychological assessment (psycholgoical testing) is a field characterized by the use of samples of behavior in order to infer generalizations about a given individual. The technical term for the science behind psychological testing is psychometrics. By samples of behavior, one means observations over time of an individual performing tasks that have usually been prescribed beforehand, which often means scores on a test. These responses are often compiled into statistical tables that allow the evaluator to compare the behavior of the individual being tested to the responses of a norm group.

Psychological testing is not the same as psychological assessment. Psychological assessment is a process that involves the integration of information from multiple sources, such as psychological tests, and other information such as personal and medical history, description of current symptoms and problems by either self or others, and collateral information (interviews with other persons about the person being assessed). A psychological test is one of the sources of data used within the process of assessment; usually more than one test is used. All psychologists do some level of assessment when providing services to clients or patients, and may use for example, simple checklists to assess some traits or symptoms, but psychological assessment is a more complex, detailed, in-depth process. Typical types of focus for psychological assessment are to provided a diagnosis, assess level of function or disability, help direct treatment, and assess treatment outcome. 

Psychological testing allows the evaluator not only to corroborate interview data and clinical impressions, but also to go beyond the interview and collect information of broader psychological complexity. Information obtained from assessment has a scientific basis as it compares the individual against normative data. It allows the evaluator to determine how similar or dissimilar this person is to others. While individuals may attempt to “look good” or “look bad” in interview depending on the case at hand, most test instruments contain validity scales on which to assess whether the individual is providing honest answers and the level of symptom minimization or distortion, if any.

Typically, an assessment consists of a diagnostic interview, psychosocial history, and a comprehensive battery of standardized tests to address a subset of the topics just listed. The diagnostic interview, which includes a mental status examination, seeks to understand the individual's current level of overall functioning. The psychosocial history provides a detailed description of the client's life story covering family of origin, childhood experiences, socialization, marriage, divorce, educational, occupational and military (if applicable), history; drug and alcohol involvement, past and current medical and psychological functioning, and past legal difficulties. Interview data provides a context in which current issues can be positioned and understood.

What are the most common psychological instruments used in an evaluation?

While there are a multitude of tests designed for different issues to be addressed in a forensic psychological evaluation, he most widely known and commonly utilized tests include:

Minnesota Multiphasic Personality Inventory-2 (MMPI-2)
The MMPI-2 is an objective personality inventory. It provides findings along multiple dimensions including clinical syndromes, personality patterns, psychosocial stressors and severity of disturbance. It is the most frequently administered and documented of all psychological test instruments. It has more than 115 translations and employed world-round. It is self-administered and consists of 567 True/False questions. Scoring provides a number of validity scales, 10 primary clinical scales and a host of content and symptom scales.

Wechsler Adult Intelligence Scale-III (WAIS-III)
The WAIS-III, the most recent of the adult Wechsler tests, published in 1997, is a general test of intelligence, IQ. It has a long history going back to 1921 when David Wechsler developed a new test of intelligence adopting the U.S. Army’s Alpha and Beta tests. These were developed to screen soldiers during World War-I to evaluate a person’s capacity to act purposefully, think rationally, and deal effectively with the environment.


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