Psych 114 Research Proposal:



Psych 114 Research Proposal:

Is there a difference between psychopaths and normal adults in their fear response and level of arousal?

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Is there a difference between psychopaths and normal adults in their fear response and level of arousal?

According to Dr. Robert Hare,

Psychopathy is a socially devastating disorder defined by a constellation of affective, interpersonal, and behavioral characteristics including egocentricity, impulsivity, irresponsibility, shallow emotions, lack of empathy, guilt, or remorse, pathological lying, manipulativeness, and the persistent violation of social norms and expectations (Maier).

This disorder not only affects the inflicted person but also puts the rest of society at risk. For many years researchers have wondered why these individuals are so different from the rest of society. Is it how nature and their environment have shaped them? Or is it more biologically based?

Research has shown that psychopaths do display a different startle response than normal adults (Bradley, Levenston, Patrick & Lang, 2000). For instance, in one study consisting of 36 participants, half of which were considered psychopathic, results were found that psychopaths have greater eyeblink inhibition to both positive and negative stimuli and a lower skin conductance rate to thrilling stimuli than normal adults do (Bradley, Levenston, Patrick & Lang, 2000). These researchers listed many explanations other scientists have come up with as to why this may be including one that proposes that these individuals have a hard time empathizing with other and may indeed enjoy seeing other people in distress. Another explanation proposes that psychopaths are “predatory individuals” and therefore respond only when threat is present (Bradley, Levenston, Patrick & Lang, 2000). In addition, other research has suggested that there is a “dissociation between emotional and cognitive processing” in psychopaths that may explain their lack of guilt, fear as well as other emotions most individuals feel (Birbaumer et al, 2005). In the study conducted by Birbaumer et al., 10 psychopaths and 10 healthy controls were used to compare conditioned responses to fear. The researchers found that the two groups differed significantly in multiple brain regions involved with the limbic system including the anterior cingulate and the left amygdala. This study found that psychopaths had a hard time being conditioned to fearful stimuli and proposed that the issue may lie in the malfunctioning of the limbic system, which is the system involved with emotional processing. They reasoned that these individuals do not develop a fear response because they cannot attribute emotions to stimuli properly (Birbaumer et al, 2005).

These studies taken together suggest significant biological differences between those with psychopathic traits and those without. However, they do not rule out the possibility that environment plays a critical role in the development of psychopaths.

The purpose of this research is to see how psychopaths respond to fear and how that response is different from normal adults. By conducting this study I hope to help expand the knowledge that scientists have about psychopaths. Scientists hopefully can then eventually use this knowledge to help these individuals through the creation of effective medications or conditioning techniques that allow for a more normal startle and fear response. My hypothesis is that psychopaths will need more threatening and fearful stimulation than most adults need to illicit a startle response. In addition, I predict that abnormalities in the functioning of the amygdala will contribute to the need for more stimulation. Facial EMG will be used to assess startle response because it allows for simultaneous recordings of the following measures seen in a startle response: orbicularis oculi (eye blink), corrugator (frowning), and the zygomaticus (smiling). The hypothesis will be supported if significantly lowered EMG responses in the orbicularis oculi and the corrugator of psychopaths result. Functional magnetic resonance imaging will be used to measure brain differences in the amygdala because this technique allows for better temporal and spatial resolution as well as more “fine-grained distinctions between subregions” (Johnstone, Kim & Whalen, pg 315). In this second procedure the hypothesis will be considered supported if BOLD images display significant brain activity differences between the two groups, specifically showing that the amygdala is less activated in psychopathic individuals.

Method

Participants

This study will consist of a total of thirty consenting adults (aged 18-45) broken up into two groups of fifteen each. The first group will be the control group. To fit the criteria for the control group, each individual must have never been diagnosed or at risk for any mental condition, including any psychopathic traits, nor any anxiety disorder. This group will be recruited through flyers and ads. Ideally, the subjects will be from all backgrounds and not just include those who have attained high levels of education nor just those with little education. This range of subjects would allow us to have better comparisons of psychopaths to the normal population. The second group will be made up of the psychopathic adults. These subjects will be recruited through clinicians and may include some individuals who are currently in prison or a mental health facility. Working with this particular group may prove difficult and in some cases violence may ensue so extra caution and care must be taken into account.

Procedure

This study has two parts. First, startle response will be measured in each group using facial electromyography then an fMRI study of the amygdala will be taken. It is important that participants do not talk with one another and communicate the details of the experiment, so appointments will be scheduled so that they do not come in contact with one another.

In the first procedure, participants will be individually placed in a room with a computer while facial EMG is being recorded. After a baseline has been determined, the experimenter will start the slideshow that the participants will be watching. The show will be randomly ordered and consist of thirty positive images, such as smiling faces or sunshine, thirty neutral images, such as blank faces or pieces of furniture, and thirty negative images, such as sad faces or bloody knives. Although the images will be in random order, the same show will be shown to all participants to insure consistency. At the fifteenth negative image a loud sound will play in the room. EMG response will still be recorded throughout the whole show and will not be stopped once the sound has been played.

In the second procedure, participants will be placed in an fMRI and shown three-five minute movies. The first movie will be the neutral condition and be about how to make spaghetti. The second movie will be the fearful condition and will be about a man who is being surrounded by sharks in the middle of the ocean. Finally, the third movie will be the happy condition and be about little children opening presents on Christmas day.

Measures

Facial electromyography recordings from the first procedure will be used to measure startle response differences, including eye blink, between the two groups. Activity in the orbicularis oculi, corrugator, and the zygomaticus during the startling noise will be compared to each individual’s baseline. Each group will then be standardized and compared against one another.

Blood-oxygenated-level-dependent (BOLD) contrast from the second procedure will be used to assess differences in brain functioning between the two groups during the same task. BOLD contrast can be shown by subtracting activity of the individual’s baseline from the experimental condition.

Anticipated Results

Using results obtained from a study conducted by Bradley et al., on the startle response of psychopathic individuals it was found that they do indeed require more threatening stimuli in order to produce a startle response. These individuals have a higher blink inhibition to both positive and negative stimuli as compared to normal individuals. This was shown through a lower EMG response to the stimuli.

The data obtained from the fMRI study conducted by Birbaumer et al., also confirms the hypothesis that amygdala functioning, specifically left amygdala functioning, in psychopaths is different from normal individuals. This study also suggested that other structures differed from the controls including the anterior cingulate, the orbitofrontal cortex, as well as other limbic structures. This was shown using the fMRI images. The researchers compared images between the two groups and found significantly lower activity in the limbic system structures in psychopaths.

Discussion

If the experiment were conducted and the data obtained was consistent with the hypothesis, it would suggest that there is a biological difference between psychopaths and normal individuals reflected by abnormalities with amygdala functioning as well as response to fearful and threatening stimuli. This abnormal response to normally fearful stimuli may have a correlation with why some psychopaths are able to commit horrific acts without feeling any remorse or fear afterwards. This data would also suggest that psychopaths have a decreased defensive reactivity to threat and therefore need to be in the presence of critical danger and threat in order to illicit an appropriate startle response (Bradley, Levenston, Patrick and Lang, 2000). The fMRI data would suggest that there is a limbic system malfunction in the psychopathic individuals (Birbaumer et al, 2005). This malfunction may also help explain why emotional significance is not attached to stimuli as quickly as it is for normal adults.

Unfortunately, there are some limitations to the startle response portion of the experiment. First, this sample did not pick psychopaths according to the severity of their disorder. If this experiment were conducted to compare extreme psychopathic individuals to non-extreme individuals it may yield a result of one having a higher need of threatening stimuli than the other in order to illicit a response. Another limitation of the proposed procedure is that it only draws assumptions about negative stimuli rather than to positive stimuli. Bradley et al, found that psychopaths do have a higher blink inhibition to positive stimuli as well when compared to normal controls. The small sample size is another limitation of the proposed study. It is not responsible to draw conclusions from such a small sample of individuals. In order to make any new, substantial assumptions from this type of study more trials should be done. It would be interesting if these trials also tested the influence of race, gender, age in addition to the severity of the disorder as mentioned above.

The second proposed procedure contains some of the same limitations as the first. For example, sample size is a huge limitation, however, it is hard to conduct multiple fMRI studies because of the cost of using an fMRI. To really learn more about the psychopathic population more studies need to be conducted despite the cost. What would be interesting to test would be to see if there is still lowered brain activation in these limbic areas when participants are being active (i.e. such as performing a feedback task to stimuli) versus passive (i.e. such as the condition proposed in this procedure).

It is interesting to look at these studies combined and look at the areas where they relate. For instance, the fMRI data of previous experiments showed that psychopaths have a disconnect between their emotional processing and their cognitive processing (Birbaumer et al, 2005). This helps explain why psychopaths lack feelings for many images and situations that normal people attach feelings to, for instance fear when seeing a man attack another man. This biological dysfunction might then be reflected in the psychopathic individual’s behavior, for example the startle reflex. More studies need to be conducted before causation can be scientifically determined, however the research suggests that there is a definite link between the two.

What the research does not suggest though, is whether the effects shown are purely biological. For instance, it is not known whether these individuals have had a hard time conditioning to fearful stimuli their whole lives and therefore the brain abnormalities would have more of an influence. In contrast, it could be that the environments in which these individuals grew up in made it so that they were desensitized to what is normally considered fearful and threatening. In this case their biological need for more threatening images as well as their brain abnormalities may have resulted from a lifetime of only responding to pertinent threatening images rather than responding to all types of fearful and threatening images. A longitudinal study that followed many psychopaths throughout their life would be the best way to get answers for these questions. This type of study though would be difficult and costly to administer so unfortunately it is unlikely to be conducted.

In conclusion, researchers have found critical differences in the physiology of psychopathic individuals. This knowledge hopefully will allow scientists as well as therapists to come up with ways that help these individuals function better in society. More research is needed until that help comes but science is making leaps and bounds every decade so treatment is not impossible.

References

Birbaumer, N., Veit, R., Lotze, M., Erb, M., Hermann, C., Grodd, W., & Flor, H. (2005). Deficient Fear

Conditioning in Psychopathy. Archives of General Psychiatry, Vol 62, 799-805. Retrieved from

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Bradley, M., Lang, P., Levenston, G., & Patrick, C. (2000). The Psychopath as Observer: Emotion and

Attention in Picture Processing. Journal of Abnormal Psychology, Vol 109, 373-385.

doi:10.1037/0021-843x.109.3.373.

Johnstone, T., Kim, M. & Whalen, P. (2009). Functional Magnetic Resonance Imaging in the Affective

and Social Neuroscience. In Harmon-Jones & Beer (Ed.), Methods in Social Neuroscience (pp. 313-

336). New York: The Guilford Press.

Maier, Gary J. M.D. (2000). Psychopathy: Antisocial, Criminal, and Violent Behavior . Retrieved from

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