ANALYZING EFFECT OF A SECONDARY COGNITIVE LOAD TASK ON A PRIMARY EXECUTIVE TASK

• US 20200135325A1
• Filed: 10/24/2019
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: TATA Consultancy Services Limited (Tata Sons Pvt Ltd.)
• Original Assignee: TATA Consultancy Services Limited (Tata Sons Pvt Ltd.)
• Inventors: GAVAS, Rahul Dasharath, CHATTERJEE, Debatri, SINHA, Aniruddha, SAHA, Sanjoy Kumar
• Granted Patent: US 12,002,568 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 5/162 Testing reaction times
• CPC Class Codes: A61B 5/163 by tracking eye movement, gaze, or pupil change
• CPC Class Codes: A61B 5/168 Evaluating attention deficit, hyperactivity
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing
• CPC Class Codes: G06F 7/588 Random number generators, i.e. based on natural stochastic processes
• CPC Class Codes: G16H 20/70 relating to mental therapies, e.g. psychological therapy or autogenous training
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

This disclosure relates to analyzing effect of a secondary cognitive load task on a primary executive task. Human random sequence generation is a marker to study cognitive functions and inability to generate random sequences (RS) can reveal underlying impairments. Traditionally, ‘call out’ or ‘write down’ procedures are used to obtain human generated numbers, wherein short term memory and number of previously generated entities visible to a subject plays a major role. Also precise trial-wise or response-wise analysis may not be possible. In the present disclosure, the human generated random numbers are digitized into RS and a cognitive load (CL) inducing task is imposed on the executive task. The CL demanding task disrupts randomization performance. Deviation from randomness, load index based on gaze data and deviation from pupillometry data of healthy subjects are provided as indicators of an interference effect imposed by the CL and thereby indicative of underlying impairments.

Claims

1. A processor implemented method (200) comprising the steps of:

assigning, by one or more hardware processors, a primary executive task to a subject, wherein the primary executive task is random number generation by the subject to obtain human generated random numbers (202);

digitizing, by the one or more hardware processors, the human generated random numbers into a random sequence (RS) in baseline by concatenating the human generated random numbers until a predetermined number of random numbers is captured or random numbers in a predetermined time period is captured, wherein the RS in baseline is generated after a first predetermined baseline period (204);

generating a random sequence in low load (LL) and a random sequence in high load (HL), by imposing, by the one or more hardware processors, a secondary cognitive load task in the form of a low cognitive load inducing task and a high cognitive load inducing task respectively, on the subject, wherein the RS in LL and the RS in HL are preceded by a pause for a second predetermined baseline period and a third predetermined baseline period respectively, to allow the subject to relax (206);

receiving, by the one or more hardware processors, gaze data and pupillometry data associated with the subject, from an eye tracker, when the primary executive task and the secondary cognitive load task are being performed by the subject (208);

extracting gaze related fixation patterns, by the one or more hardware processors, from the gaze data using a velocity based method that separates fixation points and saccade points in the gaze data based on point-to-point velocities thereof, wherein points having velocity below a predetermined threshold are fixation points, else the points are saccade points (210); and

computing, by the one or more hardware processors, a load index (A) based on summation of length of each repeating fixation extracted from the gaze data, total length of the random sequence and the total number of fixations from the gaze data (212), wherein the load index is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the value of the load index, higher is the effect of the secondary cognitive load task.

2. The processor implemented method of claim 1, wherein the step of digitizing the human generated random numbers comprises:

positioning a fixational cross ‘

+’

at the center of a white screen for the first predetermined baseline period;

displaying digits (1-9) of a predetermined font size in a 3×

3 matrix on the white screen; and

concatenating the human generated random numbers generated based on randomly clicked digits on the white screen by the subject, till the predetermined number of random numbers is captured or random numbers in the predetermined time period is captured.

3. The processor implemented method of claim 1, wherein the secondary cognitive load task involves auditory addition.

4. The processor implemented method of claim 1, wherein the first predetermined baseline period, the second predetermined baseline period and the third predetermined baseline period are equal.

5. The processor implemented method of claim 1, wherein the

6. The processor implemented method of claim 1 further comprising one or more of:

computing a deviation from randomness of the RS in baseline, the RS in LL and the RS in HL using one or more metrics including Coupon (C_n) test, Gap (G_p) test, Poker (P_k) test, Repetitions (R_p), Series (S_r), Variance of digits (VD), Digram repetitions (DR), Cluster Ratio (CR), Random Number Generator (RNG), Turning Point index (TP) (214), wherein the deviation from randomness is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the deviation from randomness, higher is the effect of the secondary cognitive load task; and

comparing the received pupillometry data of the subject with the pupillometry data of healthy subjects to analyze the effect of the secondary cognitive load task on the primary executive task (216), wherein a deviation from the pupillometry data of healthy subjects is indicative of the effect of the secondary cognitive load task on the primary executive task.

7. A system comprising:

one or more data storage devices operatively coupled to one or more hardware processors and configured to store instructions configured for execution by the one or more hardware processors to;

assign a primary executive task to a subject, wherein the primary executive task is random number generation by the subject to obtain human generated random numbers;

digitize the human generated random numbers into a random sequence (RS) in baseline by concatenating the human generated random numbers until a predetermined number of random numbers is captured or random numbers in a predetermined time period is captured, wherein the RS in baseline is generated after a first predetermined baseline period;

generate a random sequence in low load (LL) and a random sequence in high load (HL), by imposing a secondary cognitive load task in the form of a low cognitive load inducing task and a high cognitive load inducing task respectively, on the subject, wherein the RS in LL and the RS in HL are preceded by a pause for a second predetermined baseline period and a third predetermined baseline period respectively, to allow the subject to relax;

receive gaze data and pupillometry data associated with the subject, from an eye tracker, when the primary executive task and the secondary cognitive load task are being performed by the subject;

extract gaze related fixation patterns from the gaze data using a velocity based method that separates fixation points and saccade points in the gaze data based on point-to-point velocities thereof, wherein points having velocity below a predetermined threshold are fixation points, else the points are saccade points; and

compute a load index (A) based on summation of length of each repeating fixation extracted from the gaze data, the predetermined number of random numbers captured and the total number of fixations from the gaze data, wherein the load index is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the value of the load index, higher is the effect of the secondary cognitive load task.

8. The system of claim 7, wherein the one or more processors are further configured to digitize the human generated random numbers by:

positioning a fixational cross ‘

+’

at the center of a white screen for the first predetermined baseline period;

displaying digits (1-9) of a predetermined font size in a 3×

3 matrix on the white screen; and

concatenating the human generated random numbers generated based on randomly clicked digits on the white screen by the subject, till the predetermined number of random numbers is captured or random numbers in the predetermined time period is captured.

9. The system of claim 7, wherein the secondary cognitive load task involves auditory addition.

10. The system of claim 7, wherein the first predetermined baseline period, the second predetermined baseline period and the third predetermined baseline period are equal.

11. The system of claim 7, wherein the

12. The system of claim 7, wherein the one or more processors are further configured to perform one or more of:

computing a deviation from randomness of the RS in baseline, the RS in LL and the RS in HL using one or more metrics including Coupon (C_n) test, Gap (G_p) test, Poker (P_k) test, Repetitions (R_p), Series (S_r), Variance of digits (VD), Digram repetitions (DR), Cluster Ratio (CR), Random Number Generator (RNG), Turning Point index (TP), wherein the deviation from randomness is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the deviation from randomness, higher is the effect of the secondary cognitive load task; and

comparing the received pupillometry data of the subject with the pupillometry data of healthy subjects to analyze the effect of the secondary cognitive load task on the primary executive task, wherein a deviation from the pupillometry data of healthy subjects is indicative of the effect of the secondary cognitive load task on the primary executive task.

13. A computer program product comprising a non-transitory computer readable medium having a computer readable program embodied therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:

assign a primary executive task to a subject, wherein the primary executive task is random number generation by the subject to obtain human generated random numbers;

digitize the human generated random numbers into a random sequence (RS) in baseline by concatenating the human generated random numbers until a predetermined number of random numbers is captured or random numbers in a predetermined time period is captured, wherein the RS in baseline is generated after a first predetermined baseline period;

generate a random sequence in low load (LL) and a random sequence in high load (HL), by imposing a secondary cognitive load task in the form of a low cognitive load inducing task and a high cognitive load inducing task respectively, on the subject, wherein the RS in LL and the RS in HL are preceded by a pause for a second predetermined baseline period and a third predetermined baseline period respectively, to allow the subject to relax;

receive gaze data and pupillometry data associated with the subject, from an eye tracker, when the primary executive task and the secondary cognitive load task are being performed by the subject;

extract gaze related fixation patterns from the gaze data using a velocity based method that separates fixation points and saccade points in the gaze data based on point-to-point velocities thereof, wherein points having velocity below a predetermined threshold are fixation points, else the points are saccade points; and

compute a load index (A) based on summation of length of each repeating fixation extracted from the gaze data, the predetermined number of random numbers captured and the total number of fixations from the gaze data, wherein the load index is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the value of the load index, higher is the effect of the secondary cognitive load task.

14. The computer program product of claim 13, wherein the computer readable program further causes the computing device to:

compute a deviation from randomness of the RS in baseline, the RS in LL and the RS in HL using one or more metrics including Coupon (C_n) test, Gap (G_p) test, Poker (P_k) test, Repetitions (R_p), Series (S_r), Variance of digits (VD), Digram repetitions (DR), Cluster Ratio (CR), Random Number Generator (RNG), Turning Point index (TP), wherein the deviation from randomness is indicative of the effect of the secondary cognitive load task on the primary executive task and wherein higher the deviation from randomness, higher is the effect of the secondary cognitive load task; and

compare the received pupillometry data of the subject with the pupillometry data of healthy subjects to analyze the effect of the secondary cognitive load task on the primary executive task, wherein a deviation from the pupillometry data of healthy subjects is indicative of the effect of the secondary cognitive load task on the primary executive task.