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Method for determining positive and negative emotional states by electroencephalogram (EEG)

  • US 6,021,346 A
  • Filed: 07/23/1998
  • Issued: 02/01/2000
  • Est. Priority Date: 11/13/1997
  • Status: Expired due to Fees
First Claim
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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:

  • 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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