Summary
Introduction to Forensic and Legal Psychology
FSWP4020F
Master specialisation Forensic and Legal Psychology
Erasmus University Rotterdam
2020-2021
Introduction ................................................................................................................................ 2
Chapter 1. The Legal Context – Rassin, E. (2020)................................................................. 2
Chapter 2. Psychological Science – Rassin, E. (2020)........................................................... 3
Criminal responsibility ............................................................................................................... 6
Psychological Treatments That Cause Harm - Lilienfeld, S.O. (2007). ................................. 6
Defining Forensic Psycho(patho)logy - Rassin, E. (2016)................................................... 12
Bias ........................................................................................................................................... 16
Chapter 3&7. Basic Psychological Insights & Legal Fact Finding – Rassin, E. (2020). ..... 16
Investigative Psychology.......................................................................................................... 30
Chapter 5. Eyewitness Evidence – Rassin, E. (2020). ......................................................... 30
Chapter 6. Confession Evidence – Rassin, E. (2020)........................................................... 38
Evidence Evaluation and Evidentiary Power of Evidence ....................................................... 46
Chapter 7. Legal Fact Finding – Rassin, E. (2020). ............................................................. 46
Memory Enhancement ............................................................................................................. 50
Chapter 3. Basic Psychological Insights – Rassin, E. (2020). ............................................. 50
Chapter 5. Eyewitness Evidence – Rassin, E. (2020). ......................................................... 53
Compliance in an Interrogative Situation: A New Scale - Gudjonsson, G.H. (1988).......... 55
Dissociative Identity Disorder .................................................................................................. 57
The Curious Experiences Survey – Goldberg, L.R. (1999).................................................. 57
Memory Transfer for Emotionally Valenced Words Between Identities in DID – Huntjes,
R.J.C. & Colleagues (2006). ................................................................................................ 58
Objective Documentation of Child Abuse and Dissociation in 12 Murderers With DID –
Lewis, M.D. & colleagues (1997). ....................................................................................... 60
One Brain, Two Selves – Reinders, A.A.T.S. & Colleagues (2003). ................................... 62
Index ......................................................................................................................................... 63
,SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
Introduction
CHAPTER 1. THE LEGAL CONTEXT – Rassin, E. (2020).
In the typical Dutch criminal trial, the following four questions need to be answered by the
judge:
1. Can it be established, beyond reasonable doubt, that the suspect committed the crime
of which the public prosecutor suspects him? (Legal psychology)
2. Does the behaviour displayed by the suspect qualify as a criminal act?
3. Are there any exception clauses precluding the suspects guilt? (Forensic psychology)
4. Which sanction is called for? (Forensic psychology)
Criminal fact finding falls short, for example compared to scientific fact finding, regarding the
goal (establishing perpetratorship of the suspect versus discovering the truth), the required
certainty (absence of reasonable doubt versus predetermined statistical significance level), and
methodology.
HOW TO ESTABLISH PERPETRATORSHIP
To determine that the suspect committed the crime, admissible evidence is required. Moreover,
the evidence has to be strong enough to conclude beyond reasonable doubt that the suspect
committed the crime. Notably, establishing perpetratorship, despite its legal context, is not a
legal expertise. It can hence be argued that establishing perpetratorship required historical and
scientific, rather than legal methods.
After police investigation, the judge decides whether or not there is enough incriminating
evidence to convict the suspect. There is consensus that conviction required at least two pieces
of evidence. Even if there are eight pieces of exonerating evidence, the judge can still convict
the suspect, referring to the two pieces of incriminating evidence. In sum, when determining
perpetratorship, the judge is free to display some cherry picking. ‘
EXPERTS IN INQUISITORIAL VERSUS ADVERSARIAL SYSTEMS
In an inquisitorial system, experts appointed by the judge work for and are paid by the court.
Particularly, the appointment by the court is considered to safeguard a neutral, unbiased
working attitude. This attitude is further promoted by quality standards; the NRGD for Dutch
experts. Despite the standards, there may still be a risk of bias on the side of the expert.
In an adversarial system, both parties can bring their own experts. Thus, it is very tempting for
experts to write a report that is favourable for the party that retained them.
2
,SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
CHAPTER 2. PSYCHOLOGICAL SCIENCE – Rassin, E. (2020).
Within psychology, there are four concurrent approaches:
• Psychodynamics (Freud)
There are at least three consistent themes in Freud’s work:
1. All individuals have to go through five predetermined developmental stages in
order to reach a sane mature mental state.
2. The human mental system can actually be divided in either Ich (reality principle)
, Überich (morality principle) and Es (pleasure principle), or conscious and
unconscious processing.
3. We all have unconscious defence mechanisms.
Looking back at Freud’s work from a contemporary viewpoint, several critiques are in
place:
a. It is depressing that in this approach, all individuals are bound to get into
psychological problems, if not because of flawed personality development, then
because of conflicts between mature personality structures.
b. Our conscious perception of ourselves and our environment are perceived as not
much more than a superfluous side effect of the truly important processes
occurring unconsciously.
c. Freud sometimes contradicts his own work.
d. The English translations of Freud’s work are at some point not completely
adequate.
• Behaviourism (Pavlov and Skinner)
The behaviouristic movement leaned heavily on a handful of assumptions that were at
that same time quite novel:
1. Behaviourists limited the scope of their research to overt, measurable
behaviour.
2. Behaviourists were inspired by the methodology of science. Hypotheses
need to be tested in experiments, and the results of experiments are published
in peer-reviewed journals.
3. Behaviourists favour the most most parsimonious interpretation of
observations.
4. It is assumed that individuals are virtually born equal.
[I skipped everything about conditioning, we should know this by now (pp. 12-18)].
• Cognitivism (Seligman)
Cognitivism is a synthesis between psychodynamics and behaviourism. They copied the
scientific approach of the behaviourists but wanted to study what goes on in our mind.
Cognitive psychologists are not just interested in behaviour, but also in feelings,
emotions, and thoughts. Cognitive psychology has produced much research that is of
3
, SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
interest to the domain of legal psychology, like the study of perception for eyewitness
testimony, research on memory processes in understanding of witness and suspect
testimony, and the study of decision making had yielded much insight into heuristics
and bias, and finally language.
• Neuroscience
The mission of this approach is to link psychological functions to brain regions.
HALLMARKS OF SCIENCE
Karl Popper
Modern philosophy of science was much influenced by the work of Karl Popper. Popper
believed that scientific theories (elaborate ideas about empirical phenomena) and hypotheses
(small domain predictions that follow from theory) cannot be proven by searching for
confirmation of the theory or hypothesis. Particularly, confirming evidence can sometimes be
found, even though a hypothesis is incorrect, thus resulting in a false positive conclusion.
Moreover, it is oftentimes unclear how much confirming evidence is needed to conclude that a
theory is correct.
Popper proposed that scientists should not seek confirmation but falsification of their
hypotheses. This should reduce the number of false positive conclusions. It should also evade
the problem of induction because theories are no longer confirmed by summing confirming
observations. Instead, science should seek for deduction by which general theories are used to
predict individual instances. Moreover, if scientists should seek falsification of their theories,
these theories have to be falsifiable in the first place; otherwise they will not count as scientific
theories.
In sum, Popper postulated the following advice for scientists:
1. Confirmation does not count as evidence, unless it is the result of an attempt tot falsify
and it concerns a wild, risky prediction.
2. A theory should be falsifiable and should thus include many predictions that imply
prohibitions.
3. If a hypothesis is falsified, scientists should accept this outcome, and refrain from
conjuring up reasons for the falsification other than that the hypothesis is incorrect.
Popper also noted that pure observation is difficult, if not impossible for scientists, because
they are likely to be influenced by their own hypotheses. To counter possible bias, an
experiment can be set up in a way that makes the experimenter blind (blind experiment, double-
blind experiment) to condition when gathering data from participants. Another crucial feature
of science that data are quantified and measured with validated instruments.
[I skipped the parts about reliability and validity (pp. 25-29)].
4
Introduction to Forensic and Legal Psychology
FSWP4020F
Master specialisation Forensic and Legal Psychology
Erasmus University Rotterdam
2020-2021
Introduction ................................................................................................................................ 2
Chapter 1. The Legal Context – Rassin, E. (2020)................................................................. 2
Chapter 2. Psychological Science – Rassin, E. (2020)........................................................... 3
Criminal responsibility ............................................................................................................... 6
Psychological Treatments That Cause Harm - Lilienfeld, S.O. (2007). ................................. 6
Defining Forensic Psycho(patho)logy - Rassin, E. (2016)................................................... 12
Bias ........................................................................................................................................... 16
Chapter 3&7. Basic Psychological Insights & Legal Fact Finding – Rassin, E. (2020). ..... 16
Investigative Psychology.......................................................................................................... 30
Chapter 5. Eyewitness Evidence – Rassin, E. (2020). ......................................................... 30
Chapter 6. Confession Evidence – Rassin, E. (2020)........................................................... 38
Evidence Evaluation and Evidentiary Power of Evidence ....................................................... 46
Chapter 7. Legal Fact Finding – Rassin, E. (2020). ............................................................. 46
Memory Enhancement ............................................................................................................. 50
Chapter 3. Basic Psychological Insights – Rassin, E. (2020). ............................................. 50
Chapter 5. Eyewitness Evidence – Rassin, E. (2020). ......................................................... 53
Compliance in an Interrogative Situation: A New Scale - Gudjonsson, G.H. (1988).......... 55
Dissociative Identity Disorder .................................................................................................. 57
The Curious Experiences Survey – Goldberg, L.R. (1999).................................................. 57
Memory Transfer for Emotionally Valenced Words Between Identities in DID – Huntjes,
R.J.C. & Colleagues (2006). ................................................................................................ 58
Objective Documentation of Child Abuse and Dissociation in 12 Murderers With DID –
Lewis, M.D. & colleagues (1997). ....................................................................................... 60
One Brain, Two Selves – Reinders, A.A.T.S. & Colleagues (2003). ................................... 62
Index ......................................................................................................................................... 63
,SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
Introduction
CHAPTER 1. THE LEGAL CONTEXT – Rassin, E. (2020).
In the typical Dutch criminal trial, the following four questions need to be answered by the
judge:
1. Can it be established, beyond reasonable doubt, that the suspect committed the crime
of which the public prosecutor suspects him? (Legal psychology)
2. Does the behaviour displayed by the suspect qualify as a criminal act?
3. Are there any exception clauses precluding the suspects guilt? (Forensic psychology)
4. Which sanction is called for? (Forensic psychology)
Criminal fact finding falls short, for example compared to scientific fact finding, regarding the
goal (establishing perpetratorship of the suspect versus discovering the truth), the required
certainty (absence of reasonable doubt versus predetermined statistical significance level), and
methodology.
HOW TO ESTABLISH PERPETRATORSHIP
To determine that the suspect committed the crime, admissible evidence is required. Moreover,
the evidence has to be strong enough to conclude beyond reasonable doubt that the suspect
committed the crime. Notably, establishing perpetratorship, despite its legal context, is not a
legal expertise. It can hence be argued that establishing perpetratorship required historical and
scientific, rather than legal methods.
After police investigation, the judge decides whether or not there is enough incriminating
evidence to convict the suspect. There is consensus that conviction required at least two pieces
of evidence. Even if there are eight pieces of exonerating evidence, the judge can still convict
the suspect, referring to the two pieces of incriminating evidence. In sum, when determining
perpetratorship, the judge is free to display some cherry picking. ‘
EXPERTS IN INQUISITORIAL VERSUS ADVERSARIAL SYSTEMS
In an inquisitorial system, experts appointed by the judge work for and are paid by the court.
Particularly, the appointment by the court is considered to safeguard a neutral, unbiased
working attitude. This attitude is further promoted by quality standards; the NRGD for Dutch
experts. Despite the standards, there may still be a risk of bias on the side of the expert.
In an adversarial system, both parties can bring their own experts. Thus, it is very tempting for
experts to write a report that is favourable for the party that retained them.
2
,SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
CHAPTER 2. PSYCHOLOGICAL SCIENCE – Rassin, E. (2020).
Within psychology, there are four concurrent approaches:
• Psychodynamics (Freud)
There are at least three consistent themes in Freud’s work:
1. All individuals have to go through five predetermined developmental stages in
order to reach a sane mature mental state.
2. The human mental system can actually be divided in either Ich (reality principle)
, Überich (morality principle) and Es (pleasure principle), or conscious and
unconscious processing.
3. We all have unconscious defence mechanisms.
Looking back at Freud’s work from a contemporary viewpoint, several critiques are in
place:
a. It is depressing that in this approach, all individuals are bound to get into
psychological problems, if not because of flawed personality development, then
because of conflicts between mature personality structures.
b. Our conscious perception of ourselves and our environment are perceived as not
much more than a superfluous side effect of the truly important processes
occurring unconsciously.
c. Freud sometimes contradicts his own work.
d. The English translations of Freud’s work are at some point not completely
adequate.
• Behaviourism (Pavlov and Skinner)
The behaviouristic movement leaned heavily on a handful of assumptions that were at
that same time quite novel:
1. Behaviourists limited the scope of their research to overt, measurable
behaviour.
2. Behaviourists were inspired by the methodology of science. Hypotheses
need to be tested in experiments, and the results of experiments are published
in peer-reviewed journals.
3. Behaviourists favour the most most parsimonious interpretation of
observations.
4. It is assumed that individuals are virtually born equal.
[I skipped everything about conditioning, we should know this by now (pp. 12-18)].
• Cognitivism (Seligman)
Cognitivism is a synthesis between psychodynamics and behaviourism. They copied the
scientific approach of the behaviourists but wanted to study what goes on in our mind.
Cognitive psychologists are not just interested in behaviour, but also in feelings,
emotions, and thoughts. Cognitive psychology has produced much research that is of
3
, SUMMARY INTRODUCTION TO FORENSIC AND LEGAL PSYCHOLOGY 2020/2021
interest to the domain of legal psychology, like the study of perception for eyewitness
testimony, research on memory processes in understanding of witness and suspect
testimony, and the study of decision making had yielded much insight into heuristics
and bias, and finally language.
• Neuroscience
The mission of this approach is to link psychological functions to brain regions.
HALLMARKS OF SCIENCE
Karl Popper
Modern philosophy of science was much influenced by the work of Karl Popper. Popper
believed that scientific theories (elaborate ideas about empirical phenomena) and hypotheses
(small domain predictions that follow from theory) cannot be proven by searching for
confirmation of the theory or hypothesis. Particularly, confirming evidence can sometimes be
found, even though a hypothesis is incorrect, thus resulting in a false positive conclusion.
Moreover, it is oftentimes unclear how much confirming evidence is needed to conclude that a
theory is correct.
Popper proposed that scientists should not seek confirmation but falsification of their
hypotheses. This should reduce the number of false positive conclusions. It should also evade
the problem of induction because theories are no longer confirmed by summing confirming
observations. Instead, science should seek for deduction by which general theories are used to
predict individual instances. Moreover, if scientists should seek falsification of their theories,
these theories have to be falsifiable in the first place; otherwise they will not count as scientific
theories.
In sum, Popper postulated the following advice for scientists:
1. Confirmation does not count as evidence, unless it is the result of an attempt tot falsify
and it concerns a wild, risky prediction.
2. A theory should be falsifiable and should thus include many predictions that imply
prohibitions.
3. If a hypothesis is falsified, scientists should accept this outcome, and refrain from
conjuring up reasons for the falsification other than that the hypothesis is incorrect.
Popper also noted that pure observation is difficult, if not impossible for scientists, because
they are likely to be influenced by their own hypotheses. To counter possible bias, an
experiment can be set up in a way that makes the experimenter blind (blind experiment, double-
blind experiment) to condition when gathering data from participants. Another crucial feature
of science that data are quantified and measured with validated instruments.
[I skipped the parts about reliability and validity (pp. 25-29)].
4
