چكيده به لاتين
In this study, hypnosis and hypnotic suggestions based on not understanding auditory stimuli with the help of EEG signal has been considered. Hypnosis is a powerful tool for influencing the processing and perception of stimuli and is a state of the brain system that produced by giving specific inputs. 48 healthy participants used and EEG recording was done in 96 channels. An oddball paradigm used with three types of stimuli, which include target stimuli, standard stimuli and distractor stimuli. The expriment was performed in four conditions (CON, DIS, HYP and SIM). In hypnosis condition (HYP), participants were suggested to not understand the auditory stimulus. In simulation of hypnosis condition (SIM), participants were asked to simulate the hypnosis condition and suggest a lack of understanding of the auditory stimulus. In distraction condition (DIS), when the oddball task was performed, a movie was played simultaneously. Participants were asked to pay attention to the details of the film and to answer questions about what happened after the film ended and receive an award.In control condition (CON), no suggestions were given to participants and only the oddball task was performed. In each of these conditions, participants were asked to press a button on a chair when the target stimulus was played. In this study, event-related oscillations (EROs) were analyzed. The amplitude of the P3b component in the delta band, the amplitude P2 component in the theta band, and the amplitude N2 component in the alpha frequency band were used for sensory analysis and feature extraction for data mining and machine learning. The linear discriminant analysis (LDA) classifier was used for classification. The results of sensory analysis showed that the amplitude of the P3b component for the target stimulus was larger than other stimuli in all experimental conditions. In addition, the amplitude of this component in HYP and SIM conditions was significantly reduced compared to CON and DIS conditions. The amplitude of the P2 component was larger for the standard stimulus, and the amplitude of the P2 in the DIS condition was larger than the other conditions in each of the three stimulus types. The amplitude of the N2 component for the target stimulus was larger than the other two types of stimuli (except for SIM condition). In addition, the amplitude of the P3b component for the detected target stimuli was much larger than the missing target stimuli in each of the experimental conditions. In the classification section, the 4-class model was able to separate four condtions (CON, DIS, HYP and SIM) in the best case with 77.63% accuracy. In an other resort, a 3-class classifier was modeled to distinguish three types of target stimuli, standard, and distractor in each of the conditions. In the best case, the model was able to distinguish three types of stimuli in each of the four conditions, with an average accuracy of 76.85%. As a last resort, a 2-class classifier was modeled to distinguish participants with high and low hypnotizbility, which at best, with 90.4% accuracy, separated the two groups of individuals in each of the four conditions separately. Finally, as a conclusion, we can claim that hypnotic suggestions about not understanding the auditory stimulus significantly reduce the amplitude of the P3b component, which is a perceptual and cognitive component. On the other hand, we found that the amplitude of the P2 component, which is a primary and sensory component, did not show a significant decrease. It can be concluded that hypnotic suggestions can block the perception of sensory inputs.
