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Table 1 Summary of key variables for each reviewed study

From: Neuroscientific evidence in the courtroom: a review

No expert neuroscientific testimony vs. Expert neuroscientific testimony without neuroimages
Study Number of Participants Legal Judgment Crime Condition: No expert neuroscientific testimony Condition: Expert neuroscientific testimony without neuroimages (Expert) Expert Type Additional Independent Variables Additional Dependent Variables Effect on Verdict Effect on Sentence
Saks et al., 2014 - Experiment 1 825 Death/Life sentence First degree murder No diagnosis or neuroscientific evidence Two neuroscientists affirmed the mental disorder diagnosis based on fMRI scans of the defendant’s brain Neuroscientists Diagnosis: Schizophrenia vs. psychopathy vs. healthy Responsibility, dangerousness N/A Yes: Reduced death sentences, only for defendants with Schizophrenia
Greene & Cahill, 2012 208 Death/Life sentence First degree murder Neuropsychologist testified to defendant’s psychosis diagnosis Neuropsychologist testified to psychosis diagnosis and reported cognitive deficits suggesting frontal brain damage Neuropsychologist Defendant dangerousness: low vs. high risk Responsibility, self-control, dangerousness, influence of expert testimony N/A Yes: Reduced death sentences, only for high risk defendants
Schweitzer et al., 2011 - Experiment 1 237 Verdict (first-degree/second-degree/manslaughter/not guilty) + Sentence Armed robbery + homicide Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Neuroscientist N/A N/A No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 2 294 Verdict (guilty/not guilty) + Sentence Robbery + assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 3 512 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Neuroscientist claimed that the defendant suffered from structural or functional frontal lobe damage, preventing him from being able to premeditate, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 4 433 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Meta-analysis 1374 Meta-analysis Meta-analysis Meta-analysis Meta-analysis Meta-analysis N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Mowle et al., 2016 419 Guilty/Not guilty + Sentence Robbery + assault Psychologist testified to defendant’s mental disorder and traumatic brain injury (Condition 2). Psychologist testified to defendant’s diagnosis and damage to prefrontal cortex, predisposing him to impulsivity (Condition 3). Psychologist Diagnosis: Schizophrenia vs. psychopathy N/A No: No change in verdict No: No change in sentence
Allen et al., 2019 330 Sentence Sexual assault Psychologists diagnosed defendant with an impulse control disorder Neurologists had located a large tumor in the “impulse control” region of the defendant’s brain Neurologists Treatment/dangerousness: treated and low risk of future dangerousness vs. untreatable and high risk of future dangerousness Responsibility, self-control, importance of expert testimony N/A Yes: Reduced length of prison sentences
LaDuke et al., 2018 896 Sentence Burglary + aggravated assault Facts of case (mock police report of the crime, defendant statement, defendant plea); allusion to family and friend statement in support of defendant. [VIDEO] Psychologist described the defendant’s neurological abnormalities, based on MRI/fMRI scans, and concluded that the defendant posed a high risk for future violence. Psychologist Structural vs. functional neuroimaging Culpability, dangerousness, influence of expert testimony N/A No: No change in sentence
Marshall et al., 2017 - Experiment 2 400 Sentence Murder Psychiatrist discussed psychological interview methods for psychopaths, testified that the defendant exhibited a lack of impulse control and feelings of guiltlessness, explained characteristics of psychopaths. Neuroscientist discussed fMRI research and psychopathy measurement techniques for psychopaths, testified that the defendant exhibited underactivation in amygdala and orbitofrontal cortex, explained characteristics of psychopaths. Neuroscientist N/A Self-control, dangerousness, influence of expert testimony N/A No: No change in sentence
No expert neuroscientific testimony vs. Expert neuroscientific testimony with neuroimages
Study Number of Participants Legal Judgment Crime Condition: No expert neuroscientific testimony Condition: Expert neuroscientific testimony with neuroimages (Expert+Neuroimage) Expert Type Additional Independent Variables Additional Dependent Variables Effect on Verdict Effect on Sentence
Saks et al., 2014 - Experiment 1 825 Death/Life sentence First-degree murder No diagnosis or neuroscientific evidence Expert + fMRI Neuroscientists Diagnosis: Schizophrenia vs. psychopathy vs. healthy Responsibility, dangerousness N/A No: No change in death sentences
Greene & Cahill, 2012 208 Death/Life sentence First-degree murder Neuropsychologist testified to defendant’s psychosis diagnosis Expert + MRI and PET with descriptions of behavioral implications. Neuropsychologist Defendant dangerousness: low vs. high risk Responsibility, self-control, dangerousness, influence of expert testimony N/A Yes: Reduced death sentences, only for high risk defendants
Appelbaum et al., 2015 - Experiment 3 763 Death/Life sentence First-degree murder Defense attorney claimed that the defendant’s act was impulsive Psychiatrist testified that neuroimage showed a brain abnormality which led the defendant to act impulsively. Presented MRI. Psychiatrist Crime heinousness: low vs. high Dangerousness, self-control N/A Yes: Reduced death sentences
Schweitzer et al., 2011 - Experiment 1 237 Verdict (first-degree/second-degree/manslaughter/not guilty) + Sentence Armed robbery + homicide Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Expert + fMRI Neuroscientist N/A N/A No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 2 294 Verdict (guilty/not guilty) + Sentence Robbery + assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Expert + fMRI Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 3 512 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Expert + MRI and fMRI Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 4 433 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Defense attorney claimed defendant suffered from a neurological defect preventing him from forming the requisite intent. Expert + MRI Neuroscientist N/A Responsibility, self-control Yes: Reduced verdict severity No: No change in sentence
Schweitzer et al., 2011 - Meta-analysis 1374 Meta-analysis Meta-analysis Meta-analysis Meta-analysis Meta-analysis N/A Responsibility, self-control Yes: Reduced guilty verdicts No: No change in sentence
Mowle et al., 2016 419 Guilty/Not guilty + Sentence Robbery + assault Psychologist testified to defendant’s mental disorder and traumatic brain injury (Condition 2). Expert + Brain scan Psychologist Diagnosis: Schizophrenia vs. psychopathy N/A No: No change in verdict No: No change in sentence
LaDuke et al., 2018 896 Sentence Burglary + aggravated assault Facts of case (mock police report of the crime, defendant statement, defendant plea); allusion to family and friend statement in support of defendant. Expert + MRI/fMRI (two neuroimage conditions) Psychologist Structural vs. functional neuroimaging Culpability, dangerousness, influence of expert testimony N/A No: No change in sentence
Appelbaum et al., 2015 - Experiment 1 960 Sentence Murder Defense attorney claimed that the defendant’s act was impulsive Psychiatrist testified that neuroimage showed a brain abnormality which predisposed the defendant to impulsivity and violence. Presented MRI. Psychiatrist Crime heinousness: low vs. high Dangerousness, self-control N/A No: No change in sentence
Schweitzer & Saks, 2011 1170 Guilty/NGRI or GBMI Assault Defense attorney argued that the defendant suffered from a mental disorder causing him to act irrationally and uncontrollably. Family testified to neglect and abuse of defendant as a child. Neurologist testified to MRI showing physical damage to frontal lobe, which could cause defendant to lose control over actions. Presented MRI. Second expert emphasized important of frontal lobe. Neurologist N/A Self-control Yes: Reduced guilty verdicts N/A
Gurley & Marcus, 2008 394 Guilty/NGRI Murder Psychologist and psychiatrist testified to defendant’s diagnosis Psychologist and psychiatrist testified to diagnosis and presented 4 MRI scans showing prefrontal cortex damage, which likely contributed to difficulty with impulse control. Psychologist and psychiatrist Diagnosis: Psychosis (schizophrenia) vs. psychopathy Influence of expert testimony Yes: Reduced guilty verdicts N/A
Expert neuroscientific testimony without neuroimages vs. Expert neuroscientific testimony with neuroimages
Study Number of Participants Legal Judgment Crime Condition: Expert neuroscientific testimony without neuroimages (Expert) Condition: Expert neuroscientific testimony with neuroimages (Expert+Neuroimage) Expert Type Additional Independent Variables Additional Dependent Variables Effect on Verdict Effect on Sentence
Saks et al., 2014 - Experiment 1 825 Death/Life sentence First degree murder Two neuroscientists affirmed the mental disorder diagnosis based on fMRI scans of the defendant’s brain Expert + fMRI Neuroscientists Diagnosis: Schizophrenia vs. psychopathy vs. healthy Responsibility, dangerousness N/A No: No change in death sentences
Greene & Cahill, 2012 208 Death/Life sentence First-degree murder Neuropsychologist testified to psychosis diagnosis and reported cognitive deficits suggesting frontal brain damage Expert + MRI and PET with descriptions of behavioral implications. Neuropsychologist Defendant dangerousness: low vs. high risk Responsibility, self-control, dangerousness, influence of expert testimony N/A No: No change in death sentences
Schweitzer et al., 2011 - Experiment 1 237 Verdict (first-degree/second-degree/manslaughter/not guilty) + Sentence Armed robbery + homicide Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Expert + fMRI Neuroscientist N/A N/A No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 2 294 Verdict (guilty/not guilty) + Sentence Robbery + assault Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Expert + fMRI Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 3 512 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Neuroscientist claimed that the defendant suffered from structural or functional frontal lobe damage, preventing him from being able to premeditate, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Expert + MRI and fMRI Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Experiment 4 433 Verdict (simple assault/aggravated assault/not guilty) + Sentence Assault Neuroscientist claimed that the defendant suffered from structural frontal lobe damage, preventing him from being able to premeditate and deliberate about, or form the intent to be guilty of, first or second degree murder. He was also prone to losing control and becoming enraged. Expert + MRI Neuroscientist N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Schweitzer et al., 2011 - Meta-analysis 1374 Meta-analysis Meta-analysis Meta-analysis Meta-analysis Meta-analysis N/A Responsibility, self-control No: No change in verdict No: No change in sentence
Mowle et al., 2016 419 Guilty/Not guilty + Sentence Robbery + assault Psychologist testified to defendant’s diagnosis and damage to prefrontal cortex, predisposing him to impulsivity. Expert + Brain scan Psychologist N/A N/A No: No change in verdict No: No change in sentence
LaDuke et al., 2018 896 Sentence Burglary + aggravated assault [VIDEO] Psychologist described the defendant’s neurological abnormalities, based on MRI/fMRI scans, and concluded that the defendant posed a high risk for future violence. Expert + MRI/fMRI (two neuroimage conditions) Psychologist Structural vs. functional neuroimaging Culpability, dangerousness, influence of expert testimony N/A No: No change in sentence
Marshall et al., 2017 - Experiment 1 758 Sentence Murder Neuroscientist discussed fMRI research and psychopathy measurement techniques for psychopaths, testified that the defendant exhibited underactivation in amygdala and orbitofrontal cortex, explained characteristics of psychopaths. Expert + fMRI Neuroscientist N/A Self-control, dangerousness, influenced by expert testimony N/A No: No change in sentence
Schweitzer & Saks, 2011 1170 Guilty/NGRI or GBMI Assault Neurologist testified to MRI showing physical damage to frontal lobe, which could cause defendant to lose control over actions. Second expert emphasized important of frontal lobe. Expert + MRI Neurologist N/A Self-control No: No change in verdict N/A
Baker et al., 2013 73 Guilty/Not guilty Assault Neurologist testified that an MRI revealed frontal lobe damage and that such damage could impair impulse control. Presented bar graph comparing normal brain activity to defendant’s brain activity. Neurologist testified that an MRI revealed frontal lobe damage and that such damage could impair impulse control. Presented MRI scans of normal brain and defendant’s brain. Neurologist N/A Dangerousness No: No change in verdict No: No change in degree of punishment
  1. N/A Data were not available or the variable was not used, fMRI Functional magnetic resonance imaging, MRI Magnetic resonance imaging, NGRI Not guilty by reason of insanity, GBMI Guilty but mentally ill