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Giuseppe Sartori Università di Padova Convegno "Le neuroscienze incontrano le altre discipline" Padova, Palazzo del Bo 6 maggio 2011 Il convegno è promosso dall’Università di Padova e dal Dipartimento di Psicologia generale della stessa università, con il sostegno della Fondazione Sigma Tau e della Fondazione Giannino Bassetti.
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Giuseppe SartoriUniversità di Padova
Neuroscienze e Libero Arbitrio
Free will and science
Free will Intentions
Decision-makingAgencyExecutive controlInternally vs. externally generated actions
Philosophy
Theology
Genetics
Brain or mind sciencesPhysics
Free will and conscious intentions
Conscious or purposeful plan for a future action, that exists prior to and
independently of action execution
Subjectively, is the proximal cause of movement (also called motor intention)
Intention is crucial for the experience of free will. Searle (1983) distinguishes two types of intentions:
The Libet task
Used to measure when a person
forms the motor intention to
execute an action
From Haggard, 2008, Nat Rev Neuro
Intention reported ~200 ms before
movement onset (will judgment, W)
RP starts up to 2 s before movement
Inferential processes in conscious intentions
Theoretical background
Inferential processes in conscious intentions
“Reconstruction hypothesis” of intention (e.g. Dennett & Kinsbourne, 1992; Wegner, 2002)– Based on inference– Intention is retrospectively built as the cause of the movement
Empirical evidence– Action consequences affect intention attribution (Kuhn & Brass, 2009)– TMS after movement shifts the W-judgment (Lau et al., 2007)– W-judgment is inferred from apparent time of response, rather than actual
movement (Banks & Isham, 2009)
-
+
Movement onset
0-2 sVolta
ge (µ
V)
Most studies focus on pre-movement brain processes (e.g. Libet et al., 1983; Haggard & Eimer, 1999; Soon et al., 2008) ?
Theoretical background
Inferential processes in conscious intentions
Post-action events modulate the experience of
intention
Reported time of intention is based not only on pre-action processes (i.e.
motor preparation)
W-judgment related to the apparent time of response
Role of action monitoring processes
Action-effect negativity (Nae) (Band et al., 2009). Reflects the linkage
between action and action-effects
Associated with changes in the W-judgments
Inferential processes in conscious intentions
Delayed auditory feedback signaling a response later than the actual one was delivered (5, 20, 40, or 60 ms)
16 participants (7 females, 19-24 years) performed a variant of the Libet task (Banks & Isham, 2009)
EEG activity was recorded (64 channels, ref mast)
Responding hand not
visible
Methods and procedure
Inferential processes in conscious intentions
W-judgment varied as a function of feedback delays
Results
Nae amplitude was larger for later feedbacks and
associated with shifts in the W-
judgment
• Reported time of intention (W-judgment) is partially based on inferential processes (i.e. external feedback signaling response)
• Action monitoring is involved in the experience of intention (Nae may reflect action-effect binding)
• However, results cast doubts on the Libet procedure as measure of conscious intentions– Can we exclude that participants respond as that the
intention “must have taken place” sometime before the external feedback?
Inferential processes in conscious intentions
Conclusions
Free will and science: a novel approach
Free will
Theology
Philosophy
Physics
Genetics
IntentionsDecision-makingAgencyExecutive controlInternally vs. externally generated actions
Brain or mind sciences
Free will and science: a novel approach
Free will
Theology
Philosophy
Physics
Genetics
Brain or mind sciences
Behaviour
Free will beliefs and motor preparation
Theoretical background
Free will beliefs and motor preparation
The experience of free will is tightly connected with the idea of control
(e.g. choices)
Human societies are ruled on the idea that we have free will (e.g. personal
responsibility, punishment, reward)
Theoretical background
Free will beliefs and motor preparation
Theoretical background
Neuroscientific findings challenge the nature of free will
What would happen if people are induced to disbelieve in
free will?
Free will beliefs and motor preparation
• Social psychology demonstrates that it has important behavioural consequences• Increases cheating (Vohs & Schooler, 2008)• Reduces altruistic behaviour and promotes
antisocial tendencies (Baumeister et al., 2009)
Theoretical background
Deterministic perspective (i.e. free will
is an illusion)
Ego depletionLess intentional effort
into behaviourLess responsibility for
own actions
Hypotheses
Free will beliefs and motor preparation
-
+
Movement onset
0-2 sVolta
ge (µ
V)
Readiness Potential (RP)Slow negative wave preceding voluntary movements
Modulated by level of intentionality and mental effort.
Absent or greatly reduced in automatic movements
Does disbelieving in free will alter
neurophysiological processes of motor
preparation?
Free will manipulation (deterministic worldview)
Ego depletion
(1) Disbelief in free will
(2) Reduced RP (EEG activity reflecting voluntary motor preparation)
(3) Effect already in the earlier stages of motor preparation
Hypotheses
Free will beliefs and motor preparation
Three hypotheses
• Free will belief manipulation – Participants read one of 2 texts taken from Crick’s book The
Astonishing Hypothesis and were asked to read it carefully (10’) for a comprehension test
no-free will group (n=14) control group (n=15)General concepts on consciousness. Free will was not mentioned
Key concepts conveyed by the text:“[…] Free will is an illusion […] Although we feel like we are free, our choices are pre-determined and we cannot change them […] We are nothing else than a pack of neurons“
Material and methods
Free will beliefs and motor preparation
2 groups
Free will beliefs and motor preparation
Auditory feedback signaling key press was delivered simultaneously or later than the actual response (20, 40, or 60
ms)
EEG activity was recorded (32 channels)
Methods and procedure
Free Will and Determinism scale (22 items, Likert 1-5)
In addition, Self-Control (Tangney Self-Control scale) and Social Desirability (Marlow-Crowne Social Desirability scale) were measured
Personal free will (8 items)
e.g. “I have free will even when my choices are limited by external circumstances”
General free will (14 items)
e.g. ”Life’s experiences cannot eliminate a person’s free will”
Methods and procedure
Free will beliefs and motor preparation
No-free will group reported weaker free will beliefs (personal FW scale) [t(27)=-2.86, p<.01]
Free will manpilation was effective in reducing free will belief in the no-free will group
Results
Free will beliefs and motor preparation
Reduced RP amplitude in the no-free will group [F(1,28) = 4.43, p < .05, ηp
2 = .136]
Main effect in frontal-central regions (max FCz)
Results
Free will beliefs and motor preparation
W-judgment did not differ between the 2
groups
Significant effect already at-1300 ms (i.e. early stages of motor preparation)
controlsno-free will
Results
Free will beliefs and motor preparation
Significant correlation between RP and scores on the personal FWD scale
• Basic motor preparation processes are influenced by whether people believe in free will
• The effect is clear before people become aware of the intention: pre-conscious level
• The manipulation does not affect intention at a conscious level (i.e. no differences in the W-judgments)
Conclusions
Free will beliefs and motor preparation
Conclusions
Free will beliefs and motor preparation
Dismissing free will belief
Less intentional effort and reduced sense of agency
Reduced feeling of responsibility
Careless and irresponsible behaviour
Speculative interpretation
Low self-efficacy/control beliefNegative emotions?
• Experience of intention is not only based on pre-action processes– Action-effect binding does not involve only motor
preparation, but also action monitoring
• Whether or not free will is an illusion, it is much better to believe in it!– Effects on very basic brain processes
General conclusions
• Reato d’impeto• Reazione a corto circuito
• Le intenzioni distali non sono soggette a questi effetti (premedidazione-deliberazione distale)
Psichiatria Forense
Imputabilità
• Capacità di intendere e di volere– Nesso di causa fra stato mentale patologico e
reato
• Infermità di mente– Alterazione patologica
• Come si documenta?– Approccio tassononimico - convenzionalista
Infermità di mente
PRESENZAASSENZA
CONFINE
SchizofreniaDisturbo di personalità
Alterazioni cerebraliVBM, DTI,ERP, fMRI
Alterazioni geneticheGenetica molecolare
Assenza di correlati neurali e genetici
Infermità di mente
Imaging – VBM + DTI
1.Il ricordo autobiografico
2.L’intenzione nell’azione criminosa
3.Ambiti di applicazione peritali: - Idoneità a rendere testimonianza- Vizio di mente
Due problemi centrali nel processo penale
• Autobiographical memory: personal experiences, specific, long-lasting and (usually) of significance to the self-system
• Most studies on autobiographical memory investigate how easy the information is retrieved (e.g., Crovitz & Schiffman, 1974; Kopelman, 1989).
• No studies have been conducted in order to evaluate the truthfulness of an autobiographical event.
Autobiographical memory: methods
• Autobiographical IAT•Computerizzato•Richiede due memorie autobiografiche alternative
(es. porta aperta vs porta chiusa)•Accuratezza diagnostica circa 92%•Criteri DAUBERT
Caratteristcihe dello IAT per memory-detection
The Autobiographical-IAT
The aIAT has been validated in a series of experiments:
• Card aIAT
• Mock Crime aIAT
• Holiday aIAT
• Suspension of driving license aIAT
TRUE FALSE“I'm in front of a computer” “I'm in front of a television”
CARD 4 CARD 7
“I chose card 4” “I chose card 7”
TRUE FALSE“I'm in front of a computer” “I'm in front of a television”
CARD 7 CARD 4
“I saw the card 7” “I saw the card 4”
Congruent Block for Card 4 choosers
Incongruent Block for card 7 choosers
Incongruent Block for Card 4 choosers
Congruent Block for card 7 choosers
Card IAT
Card experiment
Mock Crime experiment
Driving license experiment
700900
1100130015001700
Card selected "4 of diamonds"
Card selected "7 of clubs"
Reac
tion
Tim
e (m
s)
TRUE/Card 4 TRUE/Card 7
800
1000
1200
1400
1600
1800
2000
Guilty suspects Innocent suspectsR
eac
tio
n T
ime
(m
sec)
TRUE/I stole the CD-rom
TRUE/I did not steal the CD-rom
12001400160018002000220024002600
Drivers with suspended license
Control group
Re
acti
on
Tim
e (
mse
c)
TRUE/My driving license was suspended
TRUE/My driving license was not suspended
•Facilitating effect due to pairing of associated concepts
Card IAT: results
Accuratezza IATRelazione fra il valore del D-IAT e accuratezza diagnosticaDati di 5 esperimenti per un totale di 320 soggetti
Caratteristiche IAT per memory detection
1. Probabilità di diagnosi corretta2. Accuratezza media= 92%
• Holiday aIAT• 2 Card aIAT• 10 Card aIAT
non-faking group: standard IAT instructions;
naïve-faking group: beat the memory detector, and to
hide their true autobiographical memory to the
experimenter;
instructed-faking group: “slow down” on the congruent
block and “speed up” in the incongruent block (Fiedler &
Bluemke, 2005).
Non-faking group Naïve-faking group Instructed-faking group
500
700
900
1100
1300
1500
1700
1900
21002 Card experiment Congruent
Incongruent
Mea
n R
Ts
(mse
c)
Non-faking group Naive-faking group Instructed faking group
500
700
900
1100
1300
1500
1700
1900
2100
10 Cards experiment Congruent
Incongruent
me
an
RT
s (a
vera
ge
)
Non-faking group Naive-faking group Instructed-faking group
500
700
900
1100
1300
1500
1700
1900
2100
Holiday experiment Congruent
Incongruent
Me
an
RT
s (
ms
ec
)
Results:
Naïve fakers cannot fake the aIAT
Instructed fakers are faster in the Incongruent block than the Congruent block.
Detecting fakers
•AUC: 0.88
Conclusion: it is possible to identify subjects that tried to fake the aIAT from non fakers.
•Difference between single blocks (1, 2, and 4) and double blocks (3, 5) is larger in fakers than in non-fakers
Algorithm for detecting fakers
Method ResultsTRUE FALSE“I'm in front of a computer “I'm in front of a television”
True Intention False Intention“I will sleep in Padua” “I will sleep in Milan”
TRUE FALSE“I'm in front of a computer” “I'm in front of a television”
False Intention True Intention“I will sleep in Milan” “I will sleep in Padua”
It is possible to identify the participants’ real intentions
Intention detectionJournal of Cognitive Neuroscience 2011
Collocazione temporale dell’evento
Programmato
Casuale
Detecting prior intentions
Esempio di incontro intenzionale
• Soggetto 6: incontro intenzionale con Franco per ritrovarsi dopo tanto tempo.
• Frasi a-IAT
Incontro intenzionale:• Ho telefonato a Franco per vederci• Ho organizzato un incontro con Franco• Volevo riprendere i contatti con Franco• Volevo incontrare Franco da tempo• Ho fissato l’incontro a casa sua
Incontro casuale:1. Ho incontrato casualmente Franco2. Ho incrociato Franco facendo la spesa3. Senza volerlo ho incontrato Franco4. Per caso mi sono imbattuto in Franco5. Ho inaspettatamente visto Franco
Detecting prior intentions
Esempio di incontro casuale• Soggetto 1: incontro casuale con Patrizia al supermercato.
Incontro casuale:• Ho incrociato per caso Patrizia• Al supermercato ho visto per caso Patrizia• Venerdì all’improvviso ho trovato Patrizia• Inaspettatamente ho incontrato Patrizia• Mi si è avvicinata casualmente Patrizia
Incontro intenzionale:1. Volevo vedere Patrizia2. Ho inviato un sms a Patrizia3. Ho chiesto a Patrizia di incontrarci4. Ho fissato un appuntamento con Patrizia5. Alle 18 dovevo vedere Patrizia
Detecting prior intentions
INCONTRO INTENZIONALE
CONGRUENT= VERO/INTENZIONALE
INCONGRUENT= VERO/CASUALE
Incontro intenzionale
Numero soggetti con incontro intenzionale classificati correttamente: 12/12(1/12 appena sopra soglia)
Incontro intenzionale
INCONTRO CASUALE
CONGRUENT= VERO/INTENZIONALE
INCONGRUENT= VERO/CASUALE
congruent incongruent
Incontro casuale
Problematiche forensiE’ lamentata molto di frequenteSe provata dar luogo a “incapacità di partecipare
coscientemente al processo”Difficile da distinguere dalla amnesia simulata
Amnesia lacunare psicogena per il crimine
Ricordo Spontaneo
vs
Ricordo Appreso
Valutazione del ricordo
Tema Ricordo SPONTANEO Ricordo APPRESO
1.Ho acquisito da altri dell’accoltellamento 1. Ho un ricordo personale delle coltellate
2.Ho saputo in seguito dell'accoltellamento 2. Ricordo in modo distinto l’accoltellamento
3. So tramite altri delle coltellate inferte 3. Ho chiare in mente le coltellate inferte
4. Ho solo notizie indirette delle coltellate 4. Ho un ricordo diretto delle coltellate
5. Ho saputo da altri della mia azione 5. Ricordo in modo nitido la mia azione
Tentato Omicidio
Esempio di frasi
True/
London
False/
Paris
Caso 1
• ha ucciso la moglie con un cuscino
• Buco amnesico che inizia il giorno prima e finisce il giorno dopo
• Conosce il fatto nei dettagli perché ha letto la documentazione
Autobiographical IAT
• Ho una memoria vivida e genuina per il fatto VS
• Conosco perché ho letto nelle carte
•RISULTATO: Ha una memoria vivida e genuina Amnesia simulata
Amnesia lacunare psicogena per il crimine
True/
London
False/
Paris
Caso 2
• accoltellato padre e madre
• tentato suicidio
• amnesia post-crimine
• Conosce i fatti perché ha letto la documentazione
Autobiographical IAT
• Ho una memoria vivida e genuina per il fatto VS
• Conosco perché ho letto nelle carte
•RISULTATO: Ha una memoria indiretta amnesia dissociativa genuina
Amnesia lacunare psicogena per il crimine
• Reato d’impeto• Reazione a corto circuito
• Le intenzioni distali non sono soggette a questi effetti (premedidazione-deliberazione distale)
Psichiatria Forense