Brain-computer interface
A system and method relating to a brain-computer interface in which a visual stimulus overlaying one or more objects is provided, at least a portion of the visual stimulus having a characteristic modulation. The brain computer interface measures neural response to objects viewed by a user. The neural response to the visual stimulus is correlated to the modulation, the correlation being stronger when attention is concentrated upon the visual stimulus. The visual stimulus includes a feedback element that varies according to a measure of attention on the or each overlaid object.
1. A brain computer interface system, comprising:
a display unit for displaying image data, the image data including an object, the display unit further outputting a first respective visual stimulus to correspond to the object;
a stimulus generator for generating the first visual stimulus with a corresponding characteristic modulation;
a neural signal capture device configured to capture neural signals associated with a user; and
an interfacing device operatively coupled to the neural signal capture device and the stimulus generator, the interfacing device being configured to:
receive the neural signals from the neural signal capture device;
determine a strength of components of the neural signals having a property associated with the respective characteristic modulation of the first visual stimulus;
determine the object as an object of focus of the user based on the neural signals, the object of focus being inferred from a presence of the components of the neural signals having a property associated with the characteristic modulation of the visual stimulus; and
in response to determining the object as the object of focus, cause the stimulus generator to generate a second respective visual stimulus for the object of focus, the second respective visual stimulus including a background element having a low spatial frequency (LSF) that does not exceed 3 cycles per degree and a visual feedback element having a high spatial frequency (HSF) exceeding a threshold of 7 cycles per degree, the visual feedback element being displayed to the user with a visual effect selectively applied to the visual feedback element and not applied to the background element, the visual effect varying in accordance with the strength of the components having a property associated with the characteristic modulations of the first visual stimulus for the object of focus while the background component is not modulated.
2. The brain computer interface system of claim 1 , wherein the displayed visual effect of the visual feedback element varies as a linear function of the strength of response.
3. The brain computer interface system of claim 1 , wherein the displayed visual effect of the visual feedback element varies as a non-linear function of the strength of response.
4. The brain computer interface system of claim 3 , wherein the non-linear function is selected from a sigmoid function, a Rectified Linear Unit (RELU) function or a hyperbolic tangent function.
5. The brain computer interface system of claim 1 , wherein the displayed visual effect includes a step-wise or continuous change from an initial visual state to a final visual state.
6. The brain computer interface system of any one of claim 1 , wherein the second visual stimulus is the visual feedback element.
7. The brain computer interface system of claim 1 , wherein the visual feedback element has the characteristic modulation of the first visual stimulus, while the background element is not modulated.
8. A method of operation of a brain computer interface system, the brain computer interface system including a display unit, a stimulus generator and a neural signal capture device, the method comprising:
displaying, by the display unit, to a user, image data including an object and outputting a first visual stimulus corresponding to the object, the first visual stimulus having a characteristic modulation;
performing, by a hardware interfacing device operatively coupled to the neural signal capture device and the stimulus generator, operations comprising:
receiving neural signals from the neural signal capture device;
determining a strength of components of the neural signals having a property associated with the respective characteristic modulation of the first visual stimulus;
determining the object as an object of focus of the user based on the neural signals, the object of focus being inferred from a presence of the components of the neural signals having a property associated with the characteristic modulation of the visual stimulus; and
in response to determining the object as the object of focus, causing the stimulus generator to generate a second respective visual stimulus for the object of focus, the second respective visual stimulus including a background element having a low spatial frequency (LSF) that does not exceed 3 cycles per degree and a visual feedback element and a visual feedback element having a high spatial frequency (HSF) exceeding a threshold of 7 cycles per degree, the visual feedback element being displayed to the user with a visual effect selectively applied to the visual feedback element and not applied to the background element, the visual effect varying in accordance with the strength of the components having a property associated with the characteristic modulations of the first visual stimulus for the object of focus while the background element is not modulated.
9. The method of claim 8 , wherein the displayed visual effect of the visual feedback element varies as a linear function of the strength of response.
10. The method of claim 8 , wherein the displayed visual effect of the visual feedback element varies as a non-linear function of the strength of response.
11. A computer-readable storage medium, the computer-readable storage medium storing instructions that, when executed by a computer, cause the computer to perform operations comprising:
displaying to a user, image data including an object and a first visual stimulus corresponding to the object, the first visual stimulus having a characteristic modulation;
receiving neural signals of the user from a neural signal capture device;
determining a strength of components of the neural signals having a property associated with characteristic modulation of the first visual stimulus;
determining the object as an object of focus of the user based on the neural signals, the object of focus being inferred from a presence of the components of the neural signals having a property associated with the characteristic modulation of the visual stimulus; and
in response to determining the object as the object of focus, generating a second respective visual stimulus for the object of focus, the second respective visual stimulus including a background element having a low spatial frequency (LSF) that does not exceed 3 cycles per degree and a visual feedback element and a visual feedback element having a high spatial frequency (HSF) exceeding a threshold of 7 cycles per degree, the visual feedback element being displayed to the user with a visual effect selectively applied to the visual feedback element and not applied to the background element, the visual effect varying in accordance with the strength of the component having a property associated with the characteristic modulations of the first visual stimulus for the object of focus while the background component is not modulated.
12. The computer-readable storage medium of claim 11 , wherein the displayed visual effect of the feedback element varies as a linear function of the strength of response.
13. The computer-readable storage medium of claim 11 , wherein the displayed visual effect of the feedback element varies as a non-linear function of the strength of response.