Supplemental Materials
Effects of Behavioral Genetic Evidence on Perceptions of Criminal Responsibility and
Appropriate Punishment by P. S. Appelbaum et al., 2015, Psychology, Public Policy, and Law http://dx.doi.org/10.1037/law0000039
Note that the order in which the cases were presented was randomized.
Case 1:
Each condition contains either version a or b
Each condition contains version 1, 2, 3, or 4
Each condition contains version A, B, or C
Total: 2 x 4 x 3 = 24 conditions
In this section of the study, you will read about a legal case involving John Stalley. John has been convicted of murder and is awaiting sentencing.
You will be asked to determine John’s sentence after learning the facts of the case.
Please refrain from making a judgment until you are asked to do so.
The summary you are about to read accurately describes all the facts of the case.
The Facts
John Stalley is a 25-year-old man. He works as a carpenter, and has a girlfriend, Cindy, whom he has dated since high school.
On a Saturday night last March, John and Cindy went to a bar down the street from their house.
When John came out of the restroom, he noticed an unfamiliar man talking to Cindy and brushing against her. John confronted this person—Frank—and asked him to “step outside.”
Frank angrily said, “Let’s do this,” and the two walked outside.
A physical struggle ensued. At some point during the fight, John pulled out his utility knife and stabbed Frank. Responding to a bystander’s loud scream, the bouncers ran out of the bar and tackled John. They held him until the police arrived. Meanwhile, Frank was lying unconscious on the sidewalk in a pool of blood. He was pronounced dead at the scene by the paramedics who arrived 8 minutes later.
John was arrested and charged with murder.
[Version a:

During the trial it was revealed that Frank was stabbed once in the chest. A county coroner testified that Frank died almost instantly from the stab wound, which entered his heart.
Version b:
During the trial it was revealed that Frank was stabbed 17 times all over the body and face, including once in the eye. A county coroner testified that Frank died almost instantly from the first stab wound, which entered his heart.
]
John testified that he stabbed Frank in self-defense. He said that he took out the knife to “scare”
Frank. However, “Frank wasn’t scared by the knife. After I pulled it out, he kept beating on me, so I stabbed him because I thought my life was in danger.”
The jury did not believe the self-defense claim and John was convicted of murder.
[Version 1:
During the sentencing hearing, John’s attorney argued that John was sorry for what he did to
Frank, didn’t mean to hurt him, and just acted impulsively.
Version 2:
During the sentencing hearing, John’s attorney argued that John was sorry for what he did to
Frank, didn’t mean to hurt him, and just acted impulsively.
The attorney called a psychiatrist who testified that John is biologically inclined to impulsive behavior. The psychiatrist described the results of a genetic test showing that John has a rare form of a gene called IMP7. The results are shown in the image.
The psychiatrist explained that the green bar corresponds to that gene. According to research, people with John’s form of the gene are more likely to display impulsive behavior, including shoplifting and even violence.
Version 3:

During the sentencing hearing, John’s attorney argued that John was sorry for what he did to
Frank, didn’t mean to hurt him, and just acted impulsively.
The attorney called a psychiatrist who testified that John is biologically inclined to impulsive behavior. The psychiatrist described the results of a brain scan showing that John has a specific pattern of abnormal brain activity that, according to research, makes it more likely that a person will display impulsive behavior, including shoplifting and even violence.
Pointing to the image, he noted that John has less activity in the front of the brain compared with a normal person, which is the area of the brain that helps to control behavior. He explained that individuals with decreased activation in this area are more likely to act impulsively.
Version 4:
During the sentencing hearing, John’s attorney argued that John was sorry for what he did to
Frank, didn’t mean to hurt him, and just acted impulsively.
The attorney called a psychiatrist who testified that John is biologically inclined to impulsive behavior. The psychiatrist described the results of a genetic test and a brain scan showing that
John has a form of a gene and a specific pattern of abnormal brain activity both of which, according to research, make it more likely that a person will display impulsive behavior, including shoplifting and even violence.
Pointing to the first image, he noted that John has less activity in the front of the brain compared with a normal person, which is the area of the brain that helps to control behavior. He explained that individuals with decreased activation in this area are more likely to act impulsively.

Pointing to the second image, the psychiatrist explained that the green bar shows that John has a rare form of a gene called IMP7. According to research, people with John’s form of the gene are more likely to display impulsive behavior.
]
For these reasons, John’s attorney asks for leniency in sentencing.
[Version A:
In response, the prosecutor said that John’s actions demonstrate that he is a “bad actor”, even though he has never been convicted of a crime in the past.
Version B:
In response, the prosecutor said that John’s actions demonstrate that he is a “bad actor” who hasn’t learned his lesson about breaking the law since he was convicted two years ago for shoplifting a carton of cigarettes.
Version C:
In response, the prosecutor said that John’s actions demonstrate that he is a “bad actor” who hasn’t learned his lesson about breaking the law since he was convicted two years ago for punching his boss in the face over a dispute about cigarettes.
]
The prosecutor said that murder is a serious offense and should be punished severely.
The Decision
You have now heard all the facts in the case against John Stalley. Recall that a jury has already convicted John of murder for killing Frank. Your task is to determine the length of time John should spend in prison.
Please select the length of confinement that you feel is appropriate. Do not concern yourself with what you believe is legally appropriate. We are interested in your own opinion.
[slider scale with a range of 1 to 100 in 1-point increments; questions presented in random order]
To what extent do you believe that John is an immoral person?

How fearful of John are you?
How dangerous is John to the public?
How much control did John have over his actions?
How harshly should John be punished for his actions?
How likely is it that John suffers from an illness?
Does John deserve some form of treatment?
To what extent do you feel sympathy for John?

Case 2
Each condition contains either version a or b
Each condition contains either version 1, 2, or 3
Each condition contains either version A, B, C, or D
Total: 2 x 3 x 4 = 24 conditions
In this section of the study, you will read about a legal case involving Howard Smith. Howard has been charged with kidnapping and murder. He has pled not guilty by reason of insanity to the charges.
Your job is to determine whether Howard is guilty or not guilty by reason of insanity. Please refrain from making a judgment until you are asked to do so.
The summary you are about to read accurately describes all the facts of the case.
The Facts
Howard is a 32-year-old truck driver. He worked for a local company delivering lumber for the past four years. The company had 19 employees, including Stacy, the 28-year-old receptionist.
Howard liked Stacy. He asked her out on dates several times but Stacy always declined. “You’re a nice man,” she typically said, “but I don’t date co-workers.”
After Howard asked her out yet again, Stacy was noticeably bothered, and told Howard, “I will never go out with you. Can’t you understand that?” Howard became extremely anxious, upset, and unable to sit still. For the next few weeks, he could not sleep more than a few hours per night, and became more and more irritable and preoccupied with getting Stacy to go out with him. Howard became convinced that she would like him if she would just get to know him better. He felt his thoughts running so quickly in his head that he could not keep up with them.
Other people had trouble following his logic when he spoke. He spent most days and nights pacing back and forth in his house.
He also began to frequent strip clubs, something he had never done before, and spent his savings within a week on personal lap dances. Howard thought he was so good looking that the dancers were particularly attracted to him and he gave them lavish tips. To continue to pay for the clubs,
Howard sold his most cherished possession, a gold watch that his grandfather gave him before he died.
One week later, Howard was at a gas station when Stacy drove up. She did not see him. Howard at first did not know what to do, but he then realized that “fate” must have brought them together and he felt compelled to walk toward her. Approaching Stacy while she was fueling her car, he tried to hug her, but she pushed him away. He suddenly grabbed her by her hair, dragging her about 12 feet over to his truck. Stacy was screaming and flailing about as he pushed her into the cab of his truck and drove off.

The entire scene was captured on a closed-circuit camera at the gas station, and 3 witnesses saw the entire event. One was standing right behind Howard’s truck. All 3 witnesses positively identified Howard as the perpetrator.
[Version a:
Two days later, Stacy’s body was found dumped on the side of a road. She had several abrasions and bruises on her face, and one gunshot wound to her head. A coroner determined that she died not long after Howard drove off with her.
Version b:
Two days later, Stacy’s body was found dumped on the side of a road. She had several abrasions and bruises on her face, and several gunshot wounds, including one to the head and one to the genital area. A coroner determined that she died not long after Howard drove off with her.
]
Howard was arrested the following day without incident. He seemed agitated and could not sit in one spot. When the police told him he was under arrest for kidnapping and murder, Howard blurted out, “I did it.”
Howard told his cellmate that he hadn’t known what he was going to do when he approached
Stacy. “I was just going to talk to her but I ended up grabbing her instead,” Howard explained. “I ended up shooting her. I felt I had to do it. I don’t know why I did that.”
The Trial
Howard entered a plea of not guilty by reason of insanity to the charge of kidnapping and murder.
According to state law, a defendant must be found not guilty by reason of insanity if because of a mental disorder at the time of the incident, he lacked substantial capacity to:
1. Appreciate the wrongfulness of his conduct (i.e., recognize that he was doing something that was wrong)
Or
2. Conform his conduct to the requirements of the law (i.e., behave as the law requires)
Howard’s attorney called a psychiatrist to testify.
The psychiatrist had spent several days interviewing Howard and administering several tests. He noted that Howard had been very cooperative, and stated that Howard was being “100% truthful with me.”
The psychiatrist testified that Howard had bipolar disorder (sometimes called manic-depressive illness). “This disorder is marked by periods of depression alternating with periods of mania. A person can be his normal self for months or years and then suddenly develop depression or mania. When manic, the person’s thoughts and actions are speeded up, and the person often acts impulsively, engaging in self-destructive behavior. Frivolously spending money and engaging in casual sex are hallmarks of manic impulsivity.

The psychiatrist concluded that Howard was manic when the crime occurred. “In my opinion, his mania made it impossible for him to control his behavior.”
[Version 1:
The psychiatrist noted that Howard had never had a manic episode before.
Version 2:
The psychiatrist noted that Howard had a similar but less severe episode of mania 2 years before.
At that time too, Howard did not sleep for days on end, felt his thoughts were running very fast, and had trouble concentrating and thinking straight.
Version 3:
The psychiatrist noted that Howard had a similar episode of mania 2 years before. At that time too, Howard did not sleep for days on end, felt his thoughts were running very fast, and had trouble concentrating and thinking straight.
]
[Version A:
The psychiatrist also described the results of a cutting-edge medical test for genetic abnormalities. The process involved taking a small blood sample, which allows a direct examination of Howard’s genes. The psychiatrist showed the results in the image.
The test indicated that Howard has a type of a gene, called B2Pl, that inclines people to impulsive, violent behavior.
Version B:
The psychiatrist also described the results of a cutting-edge medical test for genetic abnormalities. The process involved taking a small blood sample, which allows a direct examination of Howard’s genes. The psychiatrist showed the results in the image.

The test indicated that Howard has a type of a gene, called B2Pl, that is a marker of increased risk for bipolar disorder.
Version C:
The psychiatrist also described the results of an analysis of Howard’s family tree. The process involved examining whether Howard’s blood relatives had any history of mental illness or violence, which would suggest a genetic cause. The family tree is presented in the image below.
The psychiatrist explained that circles represent women, squares represent men, and the dark filled-in shapes represent those who demonstrated impulsive violent behavior. The analysis indicated that Howard has a family history of impulsive violent behavior, which appears to be passed down from generation to generation.
Version D:
The psychiatrist also described the results of an analysis of Howard’s family tree. The process involved examining whether Howard’s blood relatives had any history of mental illness or violence, which would suggest a genetic cause. The family tree is presented in the image below.

The psychiatrist explained that circles represent women, squares represent men, and the dark filled-in shapes represent those who had or have bipolar disorder. The analysis indicated that
Howard has a family history of bipolar disorder, which appears to be passed down from generation to generation.
]
In closing arguments to the jury, Howard’s attorney argued that Howard should be found not guilty by reason of insanity because, based on the psychiatrist’s testimony, Howard was unable to control himself. He noted that Howard committed the crime in broad daylight, in front of witnesses, admitted it to the police, and was very sorry for what he did. He said that Howard simply couldn’t control his behavior, and that the psychiatrist’s testimony supported this.
The prosecutor responded in his closing argument by stating that Stacy was dead and Howard admitted to killing her. “He may have acted impulsively, but so do a lot of criminals. Society rightfully expects everyone, even people with poor impulse control, to obey the law. End of story,” he said.
Judicial Instructions
You have now heard all of the evidence. Imagine that you are a member of the jury that must make a decision about this case. The judge reminds you that, according to state law, a defendant must be found not guilty by reason of insanity if, because of a mental disorder at the time of the incident, he lacked substantial capacity to:
1. Appreciate the wrongfulness of his conduct (i.e., recognize that he was doing something that was wrong)
Or
2. Conform his conduct to the requirements of the law (i.e., behave as the law requires).
The judge stated that bipolar disorder is considered a mental disorder.

You must decide whether Howard lacked substantial capacity to appreciate the wrongfulness of his conduct or conform his conduct to the requirements of the law. If found not guilty by reason of insanity, Howard will be sent to a maximum security psychiatric hospital.
Please indicate whether you would find Howard guilty or not guilty by reason of insanity.
____ Howard is guilty
How long do you think Howard should remain in prison?
[Insert a slider scale with a range of 1 to 100 in 1-point increments]
____ Howard is not guilty by reason of insanity
How long do you think Howard should remain in a psychiatric hospital?
[slider scale with a range of 1 to 100 in 1-point increments]
[Respondents were also asked the 8 reaction questions shown at the end of case 1.]

Case 3:
Each condition contains either version a or b
Each condition contains version 1, 2, or 3
Each condition contains version A, B, C, or D
Total: 2 x 3 x 4 = 24 conditions
In this section of the study, you will read about a legal case involving Michael Burnett. Michael was convicted of first-degree murder.
You will be asked to determine whether Michael should receive the death sentence or life in prison without the possibility of parole. Please refrain from making a judgment until you are asked to do so.
Do you have a conviction against the death penalty so strong that you could not take an oath to fairly try a death penalty case and follow the law?
No___ Yes___
The summary you are about to read accurately describes all the facts of the case.
The Facts
On February 21, 2013, Michael Burnett, age 23, and two older accomplices entered a bank with masks on. Michael pulled out a semi-automatic pistol and demanded that everyone “get on the ground.” Everyone complied with his orders, and the two accomplices, who also had guns, climbed over the front counter to start collecting money from the bank tellers. Michael stood guard at the front door.
Responding to a silent alarm, Joe Harris—a 9-year veteran police officer—entered the bank from a side door. He yelled, “Police. Drop your weapons.” Michael immediately whirled and shot at
Joe, whose back was facing him.
[Version a:
Joe was hit once and fell to the ground. He died on the spot shortly thereafter.
Version b:
Joe was hit once and fell to the ground. Michael went and stood over Joe and repeatedly fired until his gun was empty. Joe was shot a total of 8 times and died on the spot.
]
Michael’s accomplices dropped the money they had collected, vaulted the counter, and ran out the front door. Michael followed them. Two police officers pulling up at that moment ran after them and apprehended the trio.

Michael was convicted of first-degree murder. He is now in the sentencing phase of the proceedings. At this point, you must decide the appropriate punishment for Michael.
The prosecution is seeking a death sentence, since killing a police officer in the line of duty is a capital offense.
[Version 1:
The presentence report noted that Michael had no prior convictions.
Version 2:
The presentence report noted that Michael had several prior convictions for disorderly conduct and spraying graffiti on a neighbor’s house.
Version 3:
The presentence report noted that Michael had several prior convictions for felony assault and rape.
]
[Version A:
State law requires that you consider whether there are any mitigating circumstances (i.e., reasons not to impose the death penalty), and whether “the total of the mitigation is sufficiently substantial to call for leniency.” Michael’s attorney claims that he is not deserving of the death penalty for what was a horrible but impulsive act.
Version B:
State law requires that you consider whether there are any mitigating circumstances (i.e., reasons not to impose the death penalty), and whether “the total of the mitigation is sufficiently substantial to call for leniency.” Michael’s attorney claims that he is not deserving of the death penalty for what was a horrible but impulsive act.
Michael’s attorney called a psychiatrist to testify about Michael’s predisposition to impulsive behavior. The expert evaluated Michael by conducting a genetic test for the CXT2 gene.
Pointing to the diagram below, the expert explained that the CXT-2 gene is located in a small region one of the human chromosomes. It comes in two varieties – a normal one and a short one.
The genetic test indicated that Michael tested positive for the short version of the CXT2 gene.

Recent studies have found a strong link between the short version of the CXT2 gene and various types of impulsive behavior including violence, the psychiatrist explained. He stated that the gene biologically predisposed Michael to engage in this kind of behavior.
The psychiatrist said that Michael is not like a normal member of society, when it comes to controlling his actions. “Michael did horrible things in part because it is more difficult for him to avoid reacting impulsively,” he stated. “He is like a kid who acts on impulses without thinking them through, and this is certainly a result of his biological makeup.”
In the closing argument, the prosecutor said, “Michael chose to rob that bank and to kill Joe
Harris. He and his accomplices decided to kill anyone who got in their way. The genetic study doesn’t negate the fact that he chose to do those things. And if it shows you anything, it’s just how dangerous a person he is.”
Version C:
State law requires that you consider whether there are any mitigating circumstances (i.e., reasons not to impose the death penalty), and whether “the total of the mitigation is sufficiently substantial to call for leniency.” Michael’s attorney claims that he is not deserving of the death penalty for what was a horrible but impulsive act.
Michael’s attorney called a psychiatrist to testify about Michael’s predisposition to impulsive behavior. The expert evaluated Michael by conducting a functional magnetic resonance imaging
(fMRI) brain scan.
Pointing to the image, he noted that Michael has reduced activation in the pre-frontal cortex (at the arrow), which is the area of the brain responsible for regulating behavior. He explained that individuals with decreased activation are more likely to act impulsively, and stated that Michael was biologically predisposed to engage in this kind of behavior.
The psychiatrist said that Michael is not like a normal member of society, when it comes to controlling his actions. “Michael did horrible things in part because it is more difficult for him to avoid reacting impulsively,” he stated. “He is like a kid who acts on impulses without thinking them through, and this is certainly a result of his biological makeup.”

In the closing argument, the prosecutor said, “Michael chose to rob that bank and to kill Joe
Harris. He and his accomplices decided to kill anyone who got in their way. The fMRI study doesn’t negate the fact that he chose to do those things. And if it shows you anything, it’s just how dangerous a person he is.”
Version D:
State law requires that you consider whether there are any mitigating circumstances (i.e., reasons not to impose the death penalty), and whether “the total of the mitigation is sufficiently substantial to call for leniency.” Michael’s attorney claims that he is not deserving of the death penalty for what was a horrible but impulsive act.
Michael’s attorney called a psychiatrist to testify about Michael’s predisposition to impulsive behavior. The expert evaluated Michael by conducting a functional magnetic resonance imaging
(fMRI) brain scan and a genetic test for the CXT2 gene.
Pointing to the image, he noted that Michael has reduced activation in the pre-frontal cortex (at the arrow), which is the area of the brain responsible for regulating behavior. He explained that individuals with decreased activation are more likely to act impulsively, and stated that Michael was biologically predisposed to engage in this kind of behavior.
Pointing to the diagram below, the expert explained that the CXT-2 gene is located in a small region one of the human chromosomes. It comes in two varieties – a normal one and a short one.
The genetic test indicated that Michael tested positive for the short version of the CXT2 gene.

Recent studies have found a strong link between the short version of the CXT2 gene and various types of impulsive behavior including violence, the psychiatrist explained. He stated that the gene also biologically predisposed Michael to engage in this kind of behavior.
The psychiatrist said that Michael is not like a normal member of society, when it comes to controlling his actions. “Michael did horrible things in part because it is more difficult for him to avoid reacting impulsively,” he stated. “He is like a kid who acts on impulses without thinking them through, and this is certainly a result of his biological makeup.”
In the closing argument, the prosecutor said, “Michael chose to rob that bank and to kill Joe
Harris. He and his accomplices decided to kill anyone who got in their way. The fMRI and genetic studies don’t negate the fact that he chose to do those things. And if they show you anything, it’s just how dangerous a person he is.” ]
You have now heard all the evidence from the sentencing hearing. You must determine whether
Michael should receive the death penalty, or whether there are sufficient mitigating circumstances to warrant the sentence of life in prison without the possibility of parole.
Please indicate the sentence that you would select for Michael.
____ A sentence of life in prison without possibility of parole
____ A sentence of death
[Respondents were also asked the 8 reaction questions shown at the end of case 1.]