WE CLAIM: .
1. A method for detecting the point of attention of a subject who is attending to a stimulus, comprising the steps of:
establishing a calibrated response template unique 5 to the subject representing the correspondence between a stimulus and an evoked response;
providing a stimulus for evoking an EEG response in a subject;
detecting the EEG response evoked from the subject "10 by the stimulus;
mathematically correlating the EEG response with the template to derive the template response that corresponds to the EEG response; and
determining the point of attention of said subject 15 from said mathematical correlation.
2. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein the stimulus comprises a plurality of elements, and wherein the EEG response is a composite
5 response comprising responses evoked individually from each element.
3. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 2, wherein the EEG responses evoked from the stimulus elements have relative, phase differences.
A . A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 2, wherein at least two individual responses from two elements have relative frequency 5 differences.
5. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein the EEG response has a characteristic that varies depending upon the stimulus provided.
6. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein the stimulus comprises at least one element having a sensible characteristic, and wherein the stimulus evokes the EEG response by altering the sensible characteristic of the element.
7. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 6, wherein the characteristic is a visual characteristic.
8. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 7, wherein the characteristic is color.
9. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 7, wherein the characteristic is the external shape of the element.
10. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein the stimulus comprises a plurality of elements each having a visible characteristic, said elements forming a visible pattern, and wherein the stimulus evokes the EEG response by altering the pattern.
11. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein the stimulus is a visual stimulus.
12. A method for detecting the point of attention of a subject who is attending to a stimulus as claimed in claim 1, wherein said EEG response is detected simultaneously from both hemispheres of the brain.
13. A method for detecting the point of attention of a subject responding to a stimulus, comprising the steps of:
providing sensors for sensing the EEG response of a subject to a stimulus, said sensors providing a sensor response signal comprising at least two trial electrical signals representing said EEG response; conditioning the sensor response signal, including amplifying, filtering and digitizing to produce a conditioned output signal;
processing the conditioned signal to reduce noise and suppress artifacts, thereby producing a processed evoked-response potential signal representing the EEG response;
deriving a response template for comparison with the processed evoked-response potential;
mathematically correlating the processed evoked-response potential signal with the response template to determine the similarity in at least one aspect between the processed evoked-response potential signal and the response template, and providing a correlated output signal representing the degree " of similarity between the two signals; and
deriving the point of attention indicated by the correlated output signal.
14. A system for determining the point of attention of a subject responding to a stimulus, comprising:
sensor means for sensing an EEG response evoked by a stimulus and for producing an electrical signal unique to that stimulus;
amplifier means for receiving and filtering the amplified sensor signals;
filter means for receiving and filtering the amplified sensor signals;
digitizing means for receiving and digitizing the filtered signal;
means for reducing noise and suppressing artifacts in the digitized filtered signal and to output an evoked-response potential signal;
template means for providing a response template for comparison with the evoked-response potential signal;
correlator means for eliciting signal differences between the evoked-response potential signal and the response template and to output a correlator output signal; and
means for deriving the point of attention indicated by the correlation output signal.