Sensation Seeking And N100 Psychology Essay

Sensation Seeking And N100 Psychology Essay This research seeks to examine the relationship between event-related potentials, specifically the N100 component, and the personality construct of sensation seeking. Nine students enrolled in a university level introductory psychology course received credit for participating in this study. With the use of an electroencephalogram, voltage information in the brain was recorded while the participant listened to auditory stimuli including a target, standard, and random tone. After separating participants based on high and low sensation seeking scores and comparing that with an event-related potential developed from the EEG information it was shown that those high in sensation seeking had higher amplitude and a longer latency at N100 than low sensation seekers. This shows that one of the components of sensation seeking, boredom susceptibility, may have had an effect due to the repetitive presentation of stimuli which resulted in lower amplitude at the N100. Sensation seeking and N100 This study seeks to examine the relationship between levels of sensation seeking and event-related potentials (ERP), specifically the N100 component. Using ERPs to compare with personality constructs is effective because the stimulus can be time-locked to the brain activity that is being recorded and analyzed to see how the person is reacting whether on a conscious or unconscious level. Sensation seeking, as described by Marvin Zuckerman (2007), is a trait defined by the seeking of varied, novel, complex, and intense sensations and experiences, and the willingness to take physical, social, legal, and financial risks for the sake of such experience. Sensation seekers are attracted to high risk sports such as sky diving and mountain climbing, they experiment with a variety of drugs, and are sexually promiscuous in that they have a varied range of sexual partners. High sensation seekers will assess situations as low risk vs. low that will see a higher risk; even still highs will anticipate more positive arousal whereas lows anticipate fear and anxiety. Sensation seeking correlates with dominance and adventurousness, but not with neuroticism or anxiety. High sensation seekers tend to be associated with non-conformist groups and are attracted to abstract stimuli. There are four dimensions of sensation seeking that are used in Zuckermans sensation seeking scale that help determine if a person is a high or low sensation seeker. The first component is thrill and adventure seeking (TAS). If someone is high in TAS they will exert a need to be involved in activities that give them unusual sensations and experiences such as moderately risky sports. This is where activities like mountain climbing and sky diving come into play. The second aspect is experience seeking (ES) which describes the attraction to non-conformist groups. A person scoring high in experience seeking will seek out sensations and new experiences through the mind and the senses and through a nonconforming lifestyle. Activities include things like enjoying abstract art and traveling to new and different places. Disinhibition (DIS) reflects the involvement in wild parties, susceptibility to drugs, and promiscuity. Disinhibition alone can be normal, but when paired with aggression it can be a sign of psychopathy. The last subscale is boredom susceptibility (BS) defines the aversion sensation seekers have to monotonous tasks and people they find to be boring. For example, Zuckermans stimulus deprivation task found that high sensations seekers, when in a room for any length of time with no visual or auditory stimuli got restless and bored (Zuckerman, 2007). Zuckermans theory for the biological basis of sensation seeking started with his monoamine oxidase (MAO) theory. He hypothesized that high sensation seekers have low MAO compared with low sensation seekers having high levels of MAO. Monoamine oxidase is a neurotransmitter regulator. MAO regulates the level of monoamines which include norepinephrine, dopamine, and serotonin. High levels of MAO result in reduced sensitivity to a stimulus and conversely low levels increase sensitivity. This is because if there are high levels of MAO there are lower levels of monoamines and vice versa. In summary, high sensation seekers have low levels of MAO which result in an increase of sensitivity to stimulus. The negative correlation between MAO levels and sensation seeking is also indicative of a relationship between sensation seeking and the levels of catecholamine. High levels of MAO are found in the limbic system. The limbic system is involved in pleasure and sensitivity to reward. Zuckerman wor ked under the assumption that this sensitivity in high sensation seekers produces alertness and interest in novel stimuli associated with strong orienting responses. He then merged his theory of MAO with another theory that connects the limbic system activity with levels of catecholamine and sensation seeking. It explains that dopamine controls the readiness to explore and approach novel stimuli in the environment and norepinephrine regulates the sensitivity to, or expectation of positive reinforcement (i.e.) norepinephrine and dopamine together are two components of the reward system. The nucleus accumbens (NA) is part of the limbic (reward) system and hypothesized to be the major center for sensation seeking. This may be because there are higher levels of dopamine found in the NA. Therefore, this theory relates the attributes of sensations seeking to low levels of MAO, resulting in high levels of catecholamine (dopamine and norepinephrine) in the limbic system (reward center), whi ch ultimately increases readiness to explore and approach novel stimuli in the environment and sensitivity to stimulus and positive reinforcement (Zuckerman, 1983). An event-related potential (ERP) is a wave form developed by averaging epochs from data collected using an electroencephalogram (EEG) that is a time-locked representation of the voltage activity in the brain reacting to the stimulus presented (Rugg Coles, 1995). ERPs allow analysis of stimulus on a neurological level. Like this study, it can be used with personality constructs or psychological disorders to study their effects on the reaction to stimulus in the environment. The amplitude of different components in the waveform are indicative of the strength of the reaction and the latency represents the time it takes for the reaction to occur. The EEG itself is useful, but almost impossible to use its data because its such a general collection of information. ERPs act as a funnel for important information that fine tunes the data collected with the EEG that result in data that can pin point neurological reaction whether conscious or unconscious. This is another reason ERPs are useful , they allow researchers to collect data that the participant may not even be aware of (Rugg Coles, 1995). N100 (N1) is a negative spike at approximately 100 ms after a stimulus has been presented. N1 amplitude seems to be associated with detection of a stimulus. The onset and offset of a stimulus will elicit a N1 where as the repetition of a stimulus will show a reduction in N1 amplitude. N1 does not explain any content information about the stimulus presented, it will only express when a stimulus is in the environment. Within the confines of this study using the oddball paradigm with auditory stimuli, the N1 could have been increased in amplitude by creating a larger time gap between the presentations of stimulus. Since the N1 is elicited at the onset of stimulus, by increasing the time between auditory tones the recognition of a new stimulus is larger. Another way to manipulate the amplitude of the N1 is to repeat the stimulus in random time intervals for silence length (Atienza et al., 2001). N1 amplitude can also be increased by increasing the intensity or frequency of the continuous stimuli (Naatanen, 1990). Sensation seekers have a stronger curiosity or willingness to investigate novel stimuli which means they will have stronger orienting response (OR). Orienting response occurs when presented with a moderately intense or novel stimulus. Although this study is focusing on standard stimuli it can still be considered novel. Novel, in this regard, does not mean the complexity of the stimuli; it means novel to the participants environment. Sensation seeking has been positively correlated with orienting response to a novel stimulus. According to Naatanen (1990), N1 has high amplitude at the onset and offset of stimulus. It seems to represent the participants initial response to the onset of auditory stimulus which can also described as an orienting response. Research conducted by Atienza et al. (2001), found that components of the N1 were involved in the initiation of an orienting response. Operating on the assumption that N1 is indicative of an orienting response and that high sensation see kers have stronger OR it is hypothesized that those high in sensation seeking will have a shorter latency and higher amplitude at N1 than low sensation seekers. Method Participants Nine undergraduate university students were given course credit to be involved in the study. The male and female participants were recruited from introductory psychology courses. They were required to complete five personality questionnaires. The Eysenck personality questionnaire-revised, agency and affiliation questionnaire, BISBAS, ten item personality inventory, and the sensation seeking scale were used to assess the participants personality traits. From the total sensation seeking score participants were split into two categories: scoring high on sensation seeking (4) and low on sensation seeking (5). Materials The sensation seeking scale is based upon the four subscales of the personality construct: thrill and adventure seeking, experience seeking, disinhibition, and boredom susceptibility. The scores for these four subscales are added together to give the total sensation seeking score. An electroencephalogram (EEG) was used to record voltage activity in the brain while presenting the participant with auditory stimuli. It is hooked up to an amplifier that projects a variation in voltage over time. The electrodes were placed according to the 10/20 system. This system describes that electrodes are arranged based on their distance from the two main axis: anterior-posterior and the coronal (Rugg Coles, 1995). The electrodes Fz, Cz, Pz, linked mastoids, Fcz (ground), EOG, and Fp2 were used. The linked mastoids were used for references and the EOG and Fp2 were used together to get a bipolar recording. The auditory tones including: a standard high frequency tone, target low frequency tone, and a random sound were presented using an oddball paradigm. The participant was also equipped with headphones and a remote button. Procedure The participant was required to sit in an isolated room with headphones on and listen to a sequence of auditory tones including target stimuli, standard stimuli, and a rare sound. During the presentation of the auditory stimuli the participant was asked to respond to the target tone by pressing the remote button and to essentially ignore the other sounds. The EEG picks up frequencies that are not considered usable data for this study. With the computer program Neuroscan blinks and muscle reactions were removed from the data collected. The EEG is then separated into segments or epochs to represent each time the auditory tone was presented. The base line is manipulated so all recordings were at approximately 0 amplitude. The last step was to average all of the waveforms to produce a graph representing the event-related potential at each electrode. Results On average, low sensation seekers had higher amplitude at N100 and shorter latency than high sensation seekers. Those scoring high on sensation seeking had a longer latency and lower amplitude than low sensation seekers. Table 1: Average amplitude and latency at each electrode for high and low sensation seekers ERP.png Fig. 1: Event-related potential for high and low sensation seekers in reaction to standard stimuli at the Cz electrode Discussion It was thought that those who score high on sensation seeking would have higher amplitude and a shorter latency at the N100. The results contradicted what was hypothesized in that high sensation seekers actually had lower amplitude and a longer latency at N100. From the results, it is speculated that the repetition of stimuli played on one of the components of sensation seeking: boredom susceptibility. To recap, the N100 is indicative of the onset of stimuli in the environment and has no content information. In the perspective of the N100 component and neglecting the differences in the auditory tones presented, the high sensation seeker was presented with stimuli repetitively for an extended period of time. Zuckerman (2007) stated that people high in sensation seeking dislike monotonous tasks which would explain why they would have lower amplitude at N100 than low sensation seekers. When looking at the N100 alone, Nataanen (1990) explained that with repetition of a stimulus there is a decline in N1 amplitude. The presentation of auditory tones to participants was repetitive and would have resulted in lower N100 amplitude for both high and low sensation seekers. It was also shown, in research conducted by Budd et al.(1998), that stimulus presented too closely together will result in a smaller N1 because there is not enough time for neuronal recovery. There also may be a chance, because of the lack of statistical analysis, that there is actually no significant difference between the amplitude at the N1 for high and low sensation seekers. From the research done by Carol et al. (1982) on the correlation between sensation seeking and drug selection based on the optimal level of arousal theory, it can also be speculated that there would be no significant difference between high and lows at the N100. The optimal level of arousal theory would postulate that high sensation seekers, because their optimal level of arousal is higher than low sensation seekers, would choose stimulants over depressive drugs to heighten their level of arousal. It would also be expected that low sensation seekers would be more attracted to depressants because of its dampening effect on arousal levels. Their results showed that high and low sensation seekers both enjoyed the stimulants more. Looking at these results it may be concluded that it is more realistic that there is no significant difference between high and low sensation seekers at N1 (Carol et al., 1982). The sample size was quite small with a total of 9 participants. With a larger sample the results would be more applicable to the general population. The study used male and female participants, but there was no analysis of whether females or males scored higher on sensation seeking or what that meant in terms of the results. This made it so the results and the scores could not be compared on the basis of gender. The age range of participants was limited to 17-19. Also, all of the participants were from introductory psychology courses from the same university. In future research it would be interesting, using ERP, to compare gender and the scores on the sensation seeking scale and how that would affect the results. From previous research it was thought that levels of testosterone correlated to levels of sensation seeking. That higher testosterone, more prevalently in males, had a positive relationship with high levels of sensation seeking (Zuckerman, 2007). In reference to the results in this study and its possible origin from boredom susceptibility, new research could look at the different components of sensation seeking instead of the total score and how that would affect ERP studies. In the research from Zuckermans publications, it was found that the demographic factors that most affected levels of sensation seeking were gender and age, which supports the idea of future research being done with those two aspects (Zuckerman, 2007).