Neuroscience Data and Forensic Psychiatric Examination: Opportunities, Threats, and
Limitations of the Current Debate
Almost all of the world’s legal systems assume that criminal responsibility cannot
be established if the defendant was not capable to appreciate the wrongfulness of
his/her actions (1). Furthermore, most Western Penal Codes assume that the defendant
cannot be convicted if he/she is considered unable to evaluate the circumstances surrounding
the anti-juridical fact, and/or if he/she is unable to control his/her urges, impulses,
or responses. If a subject lacked these abilities, then courts may use statements
such as “not guilty by reason of insanity,” “incapacitated person,” or “(partial)
mental insanity” (2). Recent developments of neuroscience in clinical practice have
lead to consider the potential role of neuroscience data for assessing criminal responsibility
in forensic psychiatric examination (FPE) (3). In the literature, opportunities, threats,
and limitations of the introduction of neuroscience in FPE have been widely debated
(4, 5). It has been proposed that the use of neuroscience data in FPE may, at least
in some circumstances, support the detection of such disabilities. Conversely, it
has been also stressed the potential misleading role of neuroscience data in courts.
Traditionally, the debate focused on four major issues:
(a)
renowned judgments involving the reference to neuroscience data in FPE (6
–8)
(b)
the relationship between brain abnormalities and violent behaviors leading to criminal
acts:
*
in conduct disorders (e.g., antisocial personality disorder, psychopathy, deficit
of self-control) (9
–11)
*
following traumatic brain injury (12
–14)
*
in sleep/awareness disorders (15
–17)
(c)
opportunities and limitations of neuroimaging techniques (e.g., Magnetic Resonance
Imaging, MRI; functional MRI, fMRI; Positron Emission Tomography, PET) (18, 19), behavioral
genetics (20), and lie-detection techniques (21)
(d)
Heterogeneity in admissibility criteria of neuroscience data through different legal
systems (22, 23). Let’s consider US legal system: the rules governing expert testimony
usually refer to “Frye” or “Daubert” approach (24). Furthermore, the crucial but controversial
role of Federal Rules of Evidence (notably FRE 401, FRE 403, and FRE 702) in US legal
system is a vexing issue in the literature [for a detailed description, (18)]. In
many legal system, e.g., in Italy, there is not something like Federal Rules of Evidence
and the judge has to evaluate – case by case – evidences presented by experts (e.g.,
psychiatrist, psychologist, or neurologist). If the interpretation of FRE may sometimes
be hard and misleading, no specific criteria for admissibility (except for judge’s
decision) may be also extremely dangerous.
Our aim is to highlight the critical issues about the conditions that support – in
specific circumstances – the introduction of neuroscience data in FPE. In other words,
before advocating or refusing the use of neuroscience data in FPE, we have to clarify
the role that these data can have in FPE (i.e., a probative value for forensic assessment).
Firstly, we shortly hint at classical cognitive paradigms and their limitations. Secondly,
we show that most of the Western Penal Codes are shaped assuming a sort of dualist
model of human cognition. Finally, we describe potential misleading implications of
neuroscience data endorsed in a dualist legal framework. Even if no neuroscience data
can definitively discriminate neither between crime nor a mental defect, and neither
between culpability nor innocence, we suggest that the introduction of neuroscience
in FPE may be – in specific circumstances – useful and compelling.
Theoretical Hurdles and Empirical Chances: Which Implications for Forensic Settings?
Classically, a dualist model of human cognition assumes a clear distinction between
two different substances: the mind and the body (25, 26). In such model, the mind
has a direct control on bodily parts. In other words, the mind (roughly speaking,
“mental states”) would control and manage the body (roughly speaking, “bodily acts”)
through a sort of direct causal relationship. Recent advances in brain researches
have arisen new theoretical dilemma. There is a widespread agreement, both in philosophy
(27, 28) and cognitive neuroscience (29, 30), that underlines the incompatibility
between neurobiological data and dualist conceptual framework. It is assumed that
if neuroscience data are introduced in a dualist model, then misleading consequences
could be taken for granted. Recent studies seem demand a break with traditional approaches
to cognition.
Classical cognitivism and many paradigms in philosophy of mind consider mental operations
clearly detached from the body, supporting the analogy between higher cognitive functions
and specific computations. Following such perspectives, the content of mental representations
should be explained in terms of pure mental states (i.e., intentions, beliefs, and
desires). From a different point of view, an embodied perspective claims that many
features of cognition deal with (causally or even constitutively) physical body (31,
32). It is still controversial the role of mental representation in embodied approaches.
Some scholars have proposed the concept of “body representation” (such as a distinctive
class of mental representation), claiming that they are the most promising notion
to promote an embodied approach to social cognition (33). Others have proposed the
notion of “embodied simulation,” arguing that one can understand others by reusing
one’s own mental states or processes such as representations formatted in terms of
bodily format (34). Both topics are hotly debated in the literature (35, 36).
Experimental studies seem support the idea that a new theoretical framework of human
cognition has to be drawn. Let’s consider an interesting case. Mirror neurons are
a distinct class of visuomotor neurons discovered in the ventral premotor cortex of
macaque monkeys (37). More recently, evidences of the existence of a mirror neurons
system in humans come from non-invasive neurophysiological techniques and neuroimaging
studies (38, 39). Anatomically, two main cortical networks with mirror properties
have been described in humans: the first one is the parieto-frontal mirror system
(formed by the parietal lobe and the premotor cortex plus the caudal part of the inferior
frontal gyrus); the second one is the limbic mirror system (formed by the insula and
anterior mesial frontal cortex) that provides a direct understanding of emotions of
others without higher order cognitive mediation (40). The role of parieto-frontal
mirror circuit is hotly debated in the literature. The major interest concerns its
functional role in action/intention understanding, in imitation, and more generally
in social cognition. Even if many mechanisms may mediate the understanding of other’s
behavior, a compelling view supports the hypothesis that parieto-frontal mirror circuit
is the only mechanism that allows to understand the action of others “from the inside”
(41). The case of mirror mechanism is emblematic; it seems support the hypothesis
that recent advances in neuroscience demand a new theory of action execution, of action
perception, and more generally a new model for human cognition. Such theoretical considerations
are not without practical consequences: the value of neuroscience data can be misunderstood
if we endorse them into a misleading perspective. In the next part, we show how and
why these considerations may concern also FPE.
Dualist Model in the Forensic Field: Which Problems, if Any, with Neuroscience Data
To assess criminal responsibility, Western Penal Codes usually consider two specific
elements. The individual’s body that has materially performed a crime (res extensa,
latin for matter of facts) and individual’s mind has taken the decision to commit
the crime (res cogitans, latin for mental capabilities). As above reported, it is
also scheduled the possibility that a “mental defect” assessed in FPE restrains the
possibility to attribute criminal responsibility. This model not only seems remind
the dualist framework but it also reflects the way in which forensic psychiatrists
usually are called to make assessments about mental capability. Let’s consider the
Italian case. Italian Penal Code assumes a clear distinction between mind and body,
internal mental states, and external bodily acts. At trial, an Italian judge asked
a psychiatrist or psychologist an assessment about “mental capability” of the charged
(Codice Penale, art. 88–89) (42), that is to distinguish between crime (i.e., naively
“badness”) and mental defects (i.e., naively “madness”). However, there are some problems
if we want to improve the assessment in FPE introducing also neuroscience data. “Mental
defect” is an extremely ambiguous definition: does “mental defect” include also neurobiological
data or, more classically, does it exclusively refer to a behavioral model? Moreover,
the Italian judge asked the expert to clarify the “influence” (i.e., they intend causal
link or deterministic relationship) between such as “mental defect” and mental abilities
during the criminal act. In a dualist perspective, where mind (i.e., “mental states”)
directly control the body (i.e., “bodily acts”), it is possible to suppose a causal
link between “mental defect” and specific behavior (e.g., aggression). From the perspective
of clinical neuroscience, this is a misleading supposition. In fact, experimental
data cannot retrospectively assess such as deterministic relationship, given that
it can indicates just a statistic-laden correlation. Neuroscience cannot definitively
discriminate neither between crime and a mental defect, neither between culpability
and innocence.
Conclusive Considerations
If it is widely assumed that neuroscience data cannot be profitably endorsed in a
dualistic perspective, and if it is possible to show that the most of Western Penal
Codes are shaped on a dualistic model, then there are compelling reasons to encourage
a new perspective also in the forensic field. As above reported, it is not a theoretical
proposition without practical consequences. We have stressed the idea that empirical
data cannot directly assess criminal responsibility. Neuroscience data may be useful
– in specific and limited circumstances – to give aid to traditional forensic assessment
for mental capabilities. Clearly, not all neuroscience data may assume the same explanatory
value, and not all data may be useful in FPE. The renowned debate on fMRI data is
illustrative. On one side, researches both in biological psychiatry and neuropsychology
have been considerably improved by fMRI studies (43, 44); on the other side, the effective
implications of such studies are still controversial in clinical practice (45) and
also in different research fields (e.g., economic behaviors, forensic settings, moral
development, etc.) (18, 46, 47). Nevertheless, the debate on the probative value of
specific neuroscientific techniques overcomes the aim of this work.
In conclusion, we suggest that the preliminary condition to introduce neuroscience
data in FPE is the assumption of a new perspective overcoming classical dualist models.
Such new perspective permits to rule out misleading assumptions (i.e., the deterministic
link between “mental defect” and specific behavior). Noteworthy, it is a necessary
but not sufficient condition to introduce neuroscience data in FPE, given that such
data has to be evaluated case by case.