Method and system for determining an individual's state of attention

A method for determining an individual's state of attention, which comprises the following operational steps:

• a) providing a respiratory signal capture apparatus,
• b) obtaining an individual's respiratory signal with the respiratory signal capture apparatus,
• c) segmenting said respiratory signal into a plurality of segments,
• d) extracting at least one parameter from each segment of the respiratory signal,
• e) characterising a normal state of attention for the individual by selecting a respiratory signal fragment that is considered to be normal according to a pre-established criterion and, in the event that no respiratory signal fragment is found that meets said pre-established criterion, characterising the normal state of attention for the individual on the basis of certain data stored in a memory device, and
• f) determining the individual's state of attention from the at least one parameter extracted from each segment on the basis of pre-defined rules and the normal state of attention for the individual, characterised in that:
• step f) comprises:
• determining the time between successive crossings with the same slope sign of the respiratory signal with a threshold Th obtained from the individual's respiratory signal in a normal state of attention, normalising said time between successive crossings by a time Tresp corresponding to the average respiratory period of the individual's respiratory signal in a normal state of attention, filtering to obtain a signal Ks, and filtering the absolute value of the derivative of signal Ks, normalised by the value corresponding to the average absolute value of the derivative of signal Ks in the stable respiratory interval, where threshold Th and the average respiratory period of the individual's respiratory signal in a normal state of attention are obtained from the respiratory signal fragment selected to characterise the individual's normal state of attention, or from the data stored in the memory device, in the event that no respiratory signal fragment is found that meets said pre-established criterion.

A system for determining an individual's state of attention, the system comprising:

• a respiratory signal capture apparatus;
• and
• a processor for performing the following:
• a) receiving an individual's respiratory signal from the respiratory signal capture apparatus,
• b) segmenting said respiratory signal into a plurality of segments,
• c) extracting at least one parameter from each segment of the respiratory signal,
• d) characterising a normal state of attention for the individual by selecting a respiratory signal fragment that is considered to be normal according to a pre-established criterion and, in the event that no respiratory signal fragment is found that meets said pre-established criterion, characterising the normal state of attention for the individual on the basis of certain data stored in a memory device, and
• e) determining the individual's state of attention from the at least one parameter extracted from each segment on the basis of pre-defined rules and the normal state of attention for the individual,
• wherein step c) comprises obtaining at least one fuzzy parameter from the at least one parameter extracted from each segment, and step e) comprises:
• evaluating the degree of similarity of each segment with respect to each one of a plurality of pre-determined phases, by comparing the at least one fuzzy parameter of each segment to characteristic parameters for said pre-determined phases, and determining the individual's state of attention from the degree of similarity of the segments of the signal with respect to said pre-determined phases on the basis of certain pre-defined rules.

A computer readable medium having program code means embodied therein for determining an individual's state of attention, the program code means comprising:

• a) obtaining an individual's respiratory signal from a respiratory signal capture apparatus,
• b) segmenting said respiratory signal into a plurality of segments,
• c) extracting at least one parameter from each segment of the respiratory signal,
• d) characterising a normal state of attention for the individual by selecting a respiratory signal fragment that is considered to be normal according to a pre-established criterion and, in the event that no respiratory signal fragment is found that meets said pre-established criterion, characterising the normal state of attention for the individual on the basis of certain data stored in a memory device, and
• e) determining the individual's state of attention from the at least one parameter extracted from each segment on the basis of pre-defined rules and the normal state of attention for the individual, wherein step c) comprises obtaining at least one fuzzy parameter from the at least one parameter extracted from each segment, and step e) comprises:
• evaluating a degree of similarity of each segment with respect to each one of a plurality of pre-determined phases, by comparing the at least one fuzzy parameter of each segment to characteristic parameters for said pre-determined phases, and determining the individual's state of attention from the degree of similarity of the segments of the signal with respect to said pre-determined phases on the basis of certain pre-defined rules.