Method for determining positive and negative emotional states by electroencephalogram (EEG)
First Claim
1. A method for determining positive and negative emotional states of a subject with an electroencephalogram (EEG) which uses a Fourier transform, comprising the steps of:
- a. performing a fast Fourier transform on an EEG signal measured by an electrode attached to a scalp of the subject during a specific unit of time;
b. dividing a specific frequency band of the Fourier-transformed EEG signal from step a. into subbands and calculating a relative power;
c. repeating steps a. and b. and calculating the relative power relative to time in the subbands;
d. performing a smoothing operation for obtaining an average value of the relative power measured in step c. and neighboring data, thereby ignoring fluctuations within short periods of time;
e. calculating a slope as a function of time using a least square fit for the smoothed data of step d.;
f. introducing a threshold value into the slope calculated in step e. and determining an increase or decrease against time in response to the threshold value of the slope calculated in step e.;
g. determining an emotional state as a negative emotional state if a low frequency component having the slope in step e. decreases during step f. or if a high frequency component having the slope in step e. increases during step f.; and
h. determining an emotional state as a positive emotional state when the low frequency component increases in step f. or the high frequency component decreases in step f.
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Abstract
The present invention to provide a method for determining positive and negative emotional states by using a relative power in a subband of a specific frequency band increases or decreases in the course of time. In order to realize the above object, the present invention determines positive and negative emotional states by using a relative power in a subband of a specific frequency band increases or decreases with the lapse of time. The present invention performs a Fourier transform for a unit time not an entire response time regarding a stimulus, and can be used in real time by using a time-frequency analysis method continuously executed with the lapse of time.
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Citations
4 Claims
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1. A method for determining positive and negative emotional states of a subject with an electroencephalogram (EEG) which uses a Fourier transform, comprising the steps of:
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a. performing a fast Fourier transform on an EEG signal measured by an electrode attached to a scalp of the subject during a specific unit of time; b. dividing a specific frequency band of the Fourier-transformed EEG signal from step a. into subbands and calculating a relative power; c. repeating steps a. and b. and calculating the relative power relative to time in the subbands; d. performing a smoothing operation for obtaining an average value of the relative power measured in step c. and neighboring data, thereby ignoring fluctuations within short periods of time; e. calculating a slope as a function of time using a least square fit for the smoothed data of step d.; f. introducing a threshold value into the slope calculated in step e. and determining an increase or decrease against time in response to the threshold value of the slope calculated in step e.; g. determining an emotional state as a negative emotional state if a low frequency component having the slope in step e. decreases during step f. or if a high frequency component having the slope in step e. increases during step f.; and h. determining an emotional state as a positive emotional state when the low frequency component increases in step f. or the high frequency component decreases in step f. - View Dependent Claims (2, 3, 4)
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Specification