Read Forensic Psychology For Dummies Online
Authors: David Canter
Forensic Psychology For Dummies (88 page)
Taking IQ into account
This case illustrates the highly significant role that a psychological assessment of the defendant can play (whether a person lives or dies), as well as the ethical and professional challenges faced by any psychologist giving evidence in court (expert evidence is given to assist the court in its decision, whether the expert agrees with that decision or not).
In August 1996, Daryl Atkins was sentenced to death in Virginia, USA, for shooting Eric Nesbitt as part of a robbery. Before the death sentence was carried out, a psychologist was required to assess Atkins, and he determined that Atkins had an IQ of 59. This result categorised him as what is known as learning-disabled in the UK. This result was used as the basis for an appeal under the Eighth Amendment to the American Constitution, which disallows punishment that is ‘cruel and unusual’. The Supreme Court upheld this appeal and accepted that people with such low IQs aren’t mentally sound enough to be executed.
Forensic psychologists then apply a complex and highly developed scoring system to the answers in order to indicate a wider range of potential problems the person may have, including schizophrenia, hypochondria, depression, and the sort of psychopathy (something I describe in Chapter 10) that relates to disrespect for society’s rules.
The test also includes measures of whether the respondent is faking good or faking bad, or generally lying, but as with all attempts to tell how honest respondents are being, considerable debate remains about the validity of these measures. The MMPI’s detailed range of questions is probably one reason why it’s so often used as the basis for forensic evidence despite continuing discussion of its effectiveness.
Identifying the Different Aspects That Measurement Methods Assess
In this section, I look at the different areas of psychological functioning that the methods from the earlier section ‘Getting to Grips with Psychological Measurement Methods’ typically assess. Most of the methods can investigate all the following areas, but clearly some are better suited than others to certain aspects. The details that follow relate to the general population as well as to offenders, who are after all from the general population! (For a description of assessment methods specifically and directly related to forensic issues, turn to Chapter 10.)
Aptitude tests
Loads of tests are tuned to determining a person’s skills and talents. They tend to focus on specific tasks that are relevant to particular jobs, such as making sense of diagrams or having a relevant vocabulary or numeracy skills. They’re rarely relevant in forensic settings and so I don’t discuss these any further. I suppose they could be of significance in an employment tribunal where a person complained of unfair dismissal, but I’ve never heard of them being used in that situation.
Thinking ability: Cognitive tests
Mental ability and
cognition
(that is, the ways a person thinks and how effective it is) is such a significant part of human functioning that many tests have been developed to explore different aspects of it. The ubiquitous intelligence test is only one of the many examples of cognitive tests that exist. In general they explore three aspects of intellectual performance:
Attention:
Some forms of mental disturbance can have a direct influence on the ability to attend to specific tasks, or the readiness with which a person can be distracted from concentrating.
Many different aspects of memory can be assessed. I discuss the nature of memory in Chapter 4 (because an interview really relies on getting someone to remember), but that tends to be longer-term memory. With some mental conditions, short-term, or immediate memory, can fail, something that gets more common as people get older.
People’s ability to draw logical conclusions from presented information or to formulate reasonable concepts about things is an indication of both their intellectual ability and mental state. These tests can consist, for example, of a set of differently shaped and coloured blocks that have to be assigned to sensible groups. I still remember, as a student, carrying out this test with a person suffering from dementia. All she was able to do was make pictures with them. I don’t know how she felt, but it left me traumatised trying to write a report about her.
Discerning a person’s personality
In this context
personality
is the enduring aspect of people (and not how charismatic they are or how much ‘personality’ they have). Personality has been measured for many years by asking people questions about what they like to do and how they act in various situations.
Such assessments can include questions along the lines of ‘do other people include you in their activities?’, or ‘would you rather go to a party or stay at home and read a book?’ These questionnaires (often known as
inventories
) are then analysed to determine people’s scores on a number of different aspects (called
dimensions
) of their personalities, in order to give a profile of scores across the various dimensions.
In general, most psychologists agree that it’s useful to recognise five major aspects of personality, known as the Big Five: