Forensic Psychology For Dummies by David Canter Read Free Book Online

used.
     
Validity: How well the procedure measures what it claims to measure. A measure of sexual fantasies that was in fact assessing how much pornography a person watched can be misleading, although asking the person about what he liked watching may indicate sexual preferences.
     
Validity is more difficult to establish than reliability because validity requires a careful definition of what the measurement is supposed to be measuring.
     
There are lots of other aspects of psychological measurements that are important before they can be used with confidence, but two are enough for now. You can find out about other psychological measurements in Part III.
     
Studying individual cases
     
Many breakthroughs in medicine come from the study of an individual person. Working from a single case is much easier for doctors, because usually the majority of human bodies are more or less physically the same: two arms, two eyes, the same sort of kidneys and liver (give or take a few beers!).
     
In contrast, an individual’s psychological make-up is distinctly different from the next person’s, and even if many similarities exist, everybody thinks that they’re unique. For this reason, psychologists frown on a single study as a way of making discoveries and then applying the discovery to numberless people. However, single cases are very useful in illustrating results drawn from other scientific procedures, which is how I use case-studies throughout this book.
     
Getting theoretical
     
I don’t want you to think that forensic psychology is all numbers and observation and prisoners filling in questionnaires. None of these ways of collecting information about people makes much sense unless accompanied by explanation and understanding of what the forensic psychologist is doing. In science such insights come from what is broadly known as ‘theory’.
     
Psychological theories aren’t idle speculations or impossible suggestions in the way that the word theory is often used in daily life. In the study of psychology, theories consist of carefully defined ideas that are related to each other in an argument, which is then tested by obtaining some information (usually called data) from actual situations.
     
So, when you ask whether criminals are born or created by their experiences, called the ‘nature or nurture’ question, you’re really asking which of the two broad theories about the origins of crime is most plausible.
     
As I show throughout this book, when you start to define more clearly what key concepts mean and you look for the evidence, the theories usually become more subtle and more complicated. But that’s what makes forensic psychology so fascinating.
     
Professional ethics
     
All of the activities that forensic psychologists are engaged in carry serious consequences, both legally and professionally. A person’s life or freedom can hang on what the psychologist says. There are therefore many constraints and guidelines for what forensic psychologists do. I explore ten of these in Chapter 17.
     
    Working with Others: People and Places That Forensic Psychologists Encounter
Forensic psychologists don’t spend their time locked in prison cells chatting to serial killers. They find themselves interacting with a great range of people in various ways:
     
Patients: Some people are assigned to forensic psychologists through the legal process and offered therapy or given help in other ways to cope with any psychological problems.
     
Clients: People, without personal problems, buying into assistance from forensic psychologists on matters such as getting help with setting up selection procedures, say for prison officers or policemen who work on sexual assault cases, or giving advice on interviewing procedures that may be used in many different sorts of investigations.
     
Witnesses: In some cases witnesses may need special help to cope with the legal process or even to remember more clearly what happened. Young children