Method for realizing visual space capability evaluation based on non-immersive virtual reality

Abstract

The invention provides a method for evaluating visual space capability based on non-immersive virtual reality. The method is used for a computer device and comprises the steps that a path learning interface is displayed through a display screen so that a subject can conduct path learning; the path learning interface displays a two-dimensional plane map; a specified path marked with a starting point and an ending point is arranged on the map; a virtual three-dimensional space is displayed through the display screen, so that a subject can carry out a three-dimensional virtual space walking test; when the testee carries out a three-dimensional virtual space walking test, the testee starts from the starting point, advances to the ending point along the street or returns to the starting point from the ending point according to the memorized specified path; calculating an evaluation index of the subject by using the eye movement track and the mouse action of the subject; and thus, the visual space ability of the subject is evaluated. According to the detection normal form, the visual space ability of people of different age groups or subjects with different cognitive function levels can be evaluated, and visual space testing close to a real scene is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cognitive function assessment, and in particular to a method for implementing visual-spatial ability assessment based on non-immersive virtual reality. Background Art

[0002] Visuospatial function refers to an individual's ability to walk from one location to another in familiar and unfamiliar environments. This function includes the process of encoding, storing, solidifying and retrieving spatial information. Impairment of visuospatial function is associated with difficulties in position perception, spatial orientation, distance determination and cue recognition. These impairments significantly limit the daily activities of people with impaired cognitive function and those with dementia. The assessment of visuospatial ability can be used to diagnose the disease state of patients with dementia and to assess the degree of cognitive impairment in subjects, so as to achieve early diagnosis of patients with Alzheimer's disease (AD), especially large-scale screening and diagnosis of patients with cognitive impairment before obvious symptoms appear.

[0003] At present, the most commonly used method for assessing visual-spatial ability in clinical scenarios is the neuropsychological scale questionnaire test, including the Mini Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Alzheimer's Disease Assessment Scale Cognitive subscale (ADAS-Cog), the Frontal Assessment Battery (FAB), etc. These scales have been widely used in the screening of mild cognitive impairment (MCI) and Alzheimer's disease in clinical settings. These scales assess the cognitive function of subjects from multiple dimensions (memory ability, executive ability, language ability, executive ability, visual-spatial ability, information processing ability, etc.). When using MMSE and MoCA to assess visual-spatial ability, the subject is required to redraw two overlapping pentagons (MMSE test) or a cube figure (MoCA test) on paper with a pen according to the figures given in the scale questionnaire. However, the MMSE test and the MoCA test are prone to "ceiling effect" (for groups with higher education) or "floor effect" (for groups with lower education), resulting in false negatives or false positives. The diagnostic results based on scale questionnaires are also easily interfered by many external factors and cannot truly reflect the condition of the subjects, making it difficult to detect MCI people with symptoms of premature memory loss.

[0004] Furthermore, drawing can also be used clinically to evaluate visual-spatial ability. Currently, the commonly used tests are the Clock Drawing Test (CDT) and the Rey-Osterrieth Complex Figure (RCF). The former requires the subject to draw a complete clock, including a circular dial, three hands (hour, minute and second) and 12 numbers correctly arranged at the hour position on the dial, while the latter requires the subject to draw a complex geometric figure based on memory.

[0005] The third method for assessing visual-spatial ability is the maze method. In the MATRICS consensus cognitive battery (MCCB) test, there is a set of planar maze patterns with different levels of difficulty. The subject is required to enter the maze from the entrance, and after a series of twists and turns, walk out of the maze from the exit. Start with the easiest maze and gradually upgrade to the most difficult. Based on the complexity of the maze and the subject's completion time, the subject's visual-spatial ability can be assessed.

[0006] In summary, although the above-mentioned visual-spatial ability evaluation methods in the prior art can give some results, the effectiveness and usability of these visual-spatial ability evaluation methods are not satisfactory. These evaluation methods are all based on the detection of two-dimensional plane graphics, which cannot reflect the real experience of the subjects in three-dimensional space, thus leading to contradictory conclusions.

[0007] Therefore, we urgently need to develop a new visual-spatial ability assessment method to address the defects of the above-mentioned visual-spatial ability assessment methods in the prior art. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0009] To this end, the purpose of the present invention is to propose a method for evaluating visual-spatial ability based on non-immersive virtual reality.

[0010] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a method for implementing visual-spatial ability assessment based on non-immersive virtual reality, which is used for a computer device, and the computer device includes: a mouse, a display screen, an eye tracker, a jaw rest, a memory, a processor, and a computer program stored in the memory and executable on the processor; wherein the mouse is used to control the movement of a cursor on the display screen, the display screen is used to display the test content corresponding to the method for visual-spatial ability assessment, the eye tracker is used to record the eye movement trajectory of the subject when responding to the corresponding test content, the jaw rest is used to stabilize the subject's head, and the processor is used to implement the method for visual-spatial ability assessment when executing the computer program; the method for visual-spatial ability assessment includes: step S1: after receiving an instruction to enter path learning, displaying the interface of the path learning through the display screen so that the subject can perform path learning; wherein a two-dimensional plane map is displayed on the interface of the path learning; the two-dimensional plane map is distributed with crisscrossing streets, and buildings are distributed in the blocks surrounded by the streets; a prescribed path is marked along the streets on the two-dimensional plane map, and one end of the prescribed path The first end of the prescribed path is marked as the starting point, and the other end of the prescribed path is marked as the end point, and there are several crossroads on the prescribed path; the prescribed path is the walking path that the subject needs to follow when he / she is subsequently tested for walking in a three-dimensional virtual space; when the subject is learning the path, the subject starts to memorize the prescribed path until receiving an instruction to end the path learning; wherein the crossroad is a decision point; step S2: after receiving an instruction to enter the space for walking, a virtual three-dimensional space is displayed through the display screen for the subject to perform a three-dimensional virtual space walking test; wherein the virtual three-dimensional space is a three-dimensional stereoscopic version of the two-dimensional plane map; when the subject is testing the three-dimensional virtual space walking, the subject uses the mouse to make a decision to start from the starting point and move along the street to the end point according to the memorized prescribed path, and makes a decision to move forward, turn left, turn right, or turn around at each crossroad along the way until the mouse makes a decision to reach the end point; step S3: using the subject's eye movement trajectory recorded by the eye tracker and the movement of the mouse, record and calculate the subject's evaluation index; step S4: according to the subject's evaluation index, obtain the evaluation result of the subject's visual-spatial ability.

[0011] Preferably, after step S2 and before step S3, it also includes: after receiving the instruction to enter the space and return, the subject uses the mouse to start from the end point and move along the street to the starting point according to the specified path in memory, and makes a decision to move forward, turn left, turn right, or turn around at each intersection along the way, until the mouse makes a decision to reach the starting point.

[0012] Preferably, the evaluation index of the subject includes one of the following or a combination thereof: the time to complete path learning, the number of focus points of looking at plane buildings during path learning, the total time of looking at plane buildings during path learning, the total time of completing three-dimensional virtual space walking, the segmented time of completing three-dimensional virtual space walking, the number of focus points of looking at spatial buildings during three-dimensional virtual space walking, the total time of looking at spatial buildings during three-dimensional virtual space walking, the number of decision-making errors during three-dimensional virtual space walking, the path deviation ρ of three-dimensional virtual space walking, the total time of completing three-dimensional virtual space return, the segmented time of completing three-dimensional virtual space return, the focus points of looking at spatial buildings during three-dimensional virtual space return The number of focus points, the total time of looking at spatial buildings during the three-dimensional virtual space return process, the number of decision errors during the three-dimensional virtual space return process, and the path deviation ε of the three-dimensional virtual space return; wherein, the time to complete path learning is: the time length between receiving the instruction to enter path learning and receiving the instruction to end path learning; the number of focus points on plane buildings during the path learning process is: the number of focus points on which the subject's gaze stays on the buildings on the two-dimensional plane map for more than 150 milliseconds during path learning; the total time of looking at plane buildings during path learning is: the number of focus points on which the subject's gaze stays on the buildings on the two-dimensional plane map during path learning The total duration of completing the three-dimensional virtual space walking is: the time length used by the mouse to walk from the starting point to the end point during the test of the three-dimensional virtual space walking; the segmented duration of completing the three-dimensional virtual space walking is: the time length used by the mouse to reach the N+1th decision point during the test of the three-dimensional virtual space walking; N is a positive integer greater than or equal to 1; the number of focus points of the spatial buildings looked at during the three-dimensional virtual space walking is: the number of focus points of the buildings in the three-dimensional virtual space where the subject's eyes stayed for more than 150 milliseconds during the test of the three-dimensional virtual space walking; the number of focus points of the buildings looked at during the three-dimensional virtual space walking is: the number of focus points of the buildings in the three-dimensional virtual space where the subject's eyes stayed for more than 150 milliseconds during the test of the three-dimensional virtual space walking The total time of the spatial building is: the total time that the subject's eyes stay on the focus point on the building in the three-dimensional virtual space during the test of the subject's three-dimensional virtual space walking; the number of wrong decisions during the three-dimensional virtual space walking process is: the number of wrong decisions made by the subject during the test of the subject's three-dimensional virtual space walking; the path deviation ρ of the three-dimensional virtual space walking is: the degree of deviation between the subject's real walking path in the three-dimensional virtual space and the prescribed path during the test of the subject's three-dimensional virtual space walking; the total time to complete the three-dimensional virtual space return is: the length of time it takes for the mouse to return from the end point to the starting point during the test of the subject's three-dimensional virtual space return;The segmented duration of completing the three-dimensional virtual space return is: the length of time taken by the mouse to reach the M-1 decision point from the Mth decision point in the test of the three-dimensional virtual space return; M is a positive integer greater than or equal to 2; the number of focus points of the three-dimensional virtual space return process is: the number of focus points of the three-dimensional virtual space buildings that the subject's eyes stay on for more than 150 milliseconds in the test of the three-dimensional virtual space return; the total time of the three-dimensional virtual space return process is: the total time of the focus points of the three-dimensional virtual space buildings that the subject's eyes stay on in the three-dimensional virtual space in the test of the three-dimensional virtual space return; the number of decision errors in the three-dimensional virtual space return process is: the number of wrong decisions made by the subject in the test of the three-dimensional virtual space return; the path deviation ε of the three-dimensional virtual space return is: the degree of deviation between the subject's real return path in the three-dimensional virtual space and the reverse path of the prescribed path in the test of the three-dimensional virtual space return. ;

[0013] Preferably, the calculation process of the path deviation ρ of the three-dimensional virtual space walking specifically includes: marking the decision point sequence of the specified path as X = [x1, x2, ..., x n ]; where x i is the i-th decision point on the prescribed path; wherein n is the total number of decision points on the prescribed path; the decision point sequence of the subject's real walking path in the three-dimensional virtual space is marked as Y = [y1, y2, ..., y m ]; where y j is the jth decision point on the actual walking path; wherein m is the total number of decision points on the actual walking path; according to the decision point sequence of the specified path and the decision point sequence of the actual walking path, an n×m dimension distance matrix D is constructed; wherein the element d(i,j) of the distance matrix D is the decision point x of the specified path i To the decision point y of the actual walking path j The absolute value of the distance between them; a cumulative distance matrix C is constructed from the distance matrix D; wherein the element c(i,j) of the cumulative distance matrix C is the element d(i,j) of the distance matrix D plus the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C; the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y jThe minimum cumulative distance between two points; the value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the subject's actual walking path in the three-dimensional virtual space and the prescribed path; when the subject's actual walking path is completely consistent with the prescribed path, the path deviation ρ of the three-dimensional virtual space walking is zero.

[0014] Preferably, the calculation process of the path deviation ε returned by the three-dimensional virtual space specifically includes: the reverse path of the prescribed path is opposite to the prescribed path of space walking, that is, the decision point sequence of the reverse path of the prescribed path is recorded as X =[ x n , x n-1 ,…, x1 ];in, x i is the first i decision points; wherein n is the total number of decision points on the reverse path of the prescribed path; the decision point sequence of the real return path of the subject in the three-dimensional virtual space is marked as Y =[y m ,y m-1 ,…,y 1 ]; where y j is the jth decision point on the actual return path; wherein m is the total number of decision points on the actual return path; according to the decision point sequence of the reverse path of the specified path and the decision point sequence of the actual return path, a distance matrix of dimension n×m is constructed D ; Wherein, the distance matrix D The element d(i,j) is the decision point x of the reverse path of the prescribed path. i To the decision point y of the true return path j The absolute value of the distance between D Construct a cumulative distance matrix C ; Wherein, the cumulative distance matrix C The element c(i,j) is the distance matrix D The element d(i,j) plus the cumulative distance matrix C The minimum value among the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y j The minimum cumulative distance between two points; the value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the subject's actual return path in the three-dimensional virtual space and the reverse path of the prescribed path; when the subject's actual return path in the three-dimensional virtual space is completely consistent with the reverse path of the prescribed path, the deviation ε of the path returned in the three-dimensional virtual space is zero.

[0015] Beneficial effects of the present invention:

[0016] The present invention provides a method for evaluating visual-spatial ability based on non-immersive virtual reality, and invents an evaluation method that integrates an eye-tracking system and non-immersive virtual reality technology. Non-immersive virtual reality can accurately monitor and analyze human behavior using a virtual environment, and can reflect the natural reaction of the subject to the stimulus conditions in the virtual space. In addition, the virtual environment of non-immersive virtual reality can be designed for a specific population or a specific task, and has a wide range of versatility. At the same time, this standardized virtual environment can make the test results at different locations and times comparable and referenceable, and has the potential to become a standardized tool for detecting cognitive function. In addition, studies have shown that non-immersive virtual reality technology has great advantages in evaluating the visual-spatial ability of patients with brain damage and chronic stroke patients.

[0017] Eye tracking is a new technology that can measure eye movements when subjects are objectively reading, scanning and saccade. In recent years, it has been used for cognitive function assessment, such as trajectory testing, saccades and antisaccades, emotion recognition and cognitive assessment. Eye tracking systems have unique technical advantages. First, eye movements are a spontaneous reflection of brain perceptual activities (visual and / or auditory), which are not controlled by human consciousness and can truly reflect the cognitive activities of subjects. Secondly, eye tracking systems can continuously monitor and record eye movements, providing dynamic information of cognitive performance in a real-time framework, rather than static results, such as positron emission tomography (PET), magnetic resonance imaging (MRI) or scale tests. Thirdly, the eye movement trajectory projected onto the monitor has a higher spatial resolution (pixel level) and temporal resolution (millisecond level), which can reflect the rapid activity of the brain. These digital test methods are more accurate, more convenient and more friendly to subjects than the results based on traditional "paper-pencil" questionnaire scales.

[0018] Therefore, the method for evaluating visual-spatial ability based on non-immersive virtual reality provided by the present invention provides visual stimulation to the subject while recording the non-subjective conscious response of the subject by using eye movement technology. Specifically, we designed the detection paradigms of [path learning], [spatial walking] and [spatial return] to evaluate the visual-spatial ability of people of different age groups or subjects with different cognitive function levels, realizing a visual-spatial test in the true sense. The importance of the present invention is incomparable to the currently used "paper-pencil" experimental paradigm.

[0019] In addition, compared with existing research and testing methods, our invention has the following unique features. First, in addition to the total memory duration of [path learning], we also obtained the number of focus points, focus point distribution, and focus point duration of the subjects during the [path learning] process. Secondly, we can obtain the total completion time of the subjects in [spatial walking] and [spatial return], the number of focus points of three-dimensional space landmarks, focus point distribution, focus point duration, and the number of decision errors. More importantly, for the first time, we used the path deviation index to measure the degree of deviation between the subject's actual path and the prescribed path when walking in three-dimensional space, as well as the degree of deviation between the actual path when returning and the reverse sequence of the prescribed path, which can accurately evaluate the subject's visual-spatial ability.

[0020] Additional aspects and advantages of the invention will become apparent from the following description, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic block diagram showing the working principle of a computer device according to an embodiment of the present invention;

[0022] Figure 2 A schematic flow chart showing a method for implementing visual-spatial ability assessment based on non-immersive virtual reality for a computer device according to an embodiment of the present invention;

[0023] Figure 3 A schematic diagram showing a two-dimensional map in a [path learning] test according to an embodiment of the present invention;

[0024] Figure 4 A schematic diagram showing a screenshot at the "starting point" in a [space walking] test according to an embodiment of the present invention;

[0025] Figure 5 A schematic diagram showing a screenshot of a certain intersection in a [space walking] test according to an embodiment of the present invention;

[0026] Figure 6 A schematic diagram showing a screenshot at the "end point" in a [space walking] test according to an embodiment of the present invention;

[0027] Figure 7 A schematic diagram showing the total time taken by young subjects and elderly subjects to complete path learning respectively according to an embodiment of the present invention;

[0028] Figure 8 A schematic diagram showing the number of focus points of a young subject and an elderly subject in path learning according to an embodiment of the present invention;

[0029] Figure 9a A schematic diagram showing the distribution of focus points of a young subject on a two-dimensional plane map according to an embodiment of the present invention;

[0030] Figure 9b A schematic diagram showing the distribution of focus points of an elderly subject on a two-dimensional plane map according to an embodiment of the present invention;

[0031] Fig.10 A schematic diagram showing the duration of focus points of young subjects and elderly subjects in path learning, respectively, according to an embodiment of the present invention;

[0032] Fig.11 A schematic diagram showing the total time taken by young subjects and elderly subjects to complete spatial walking respectively according to an embodiment of the present invention;

[0033] Fig.12 A schematic diagram showing the total number of focus points of a young subject and an elderly subject respectively during spatial walking according to an embodiment of the present invention;

[0034] Fig.13 A schematic diagram showing the total attention duration of a young subject and an elderly subject during spatial walking according to an embodiment of the present invention;

[0035] Fig.14 A schematic diagram showing the path deviations of a young subject and an elderly subject respectively during spatial walking according to an embodiment of the present invention;

[0036] Fig.15 A schematic diagram showing the distribution of path deviations of young subjects and elderly subjects respectively during spatial walking according to an embodiment of the present invention;

[0037] Fig.16 A schematic diagram showing a distribution diagram of a space walk first error according to an embodiment of the present invention;

[0038] Fig.17 A schematic diagram showing a spatial walking example 1 according to an embodiment of the present invention;

[0039] Fig.18 A schematic diagram showing a spatial walking example 2 of an embodiment of the present invention;

[0040] Fig.19 A schematic diagram showing a spatial walking example 3 of an embodiment of the present invention;

[0041] Fig. 20 A schematic diagram showing a spatial walking example 4 of an embodiment of the present invention;

[0042] Fig.21 A schematic diagram showing a spatial walking example 5 of an embodiment of the present invention;

[0043] Fig. 22 A schematic diagram showing a spatial walking example 6 of an embodiment of the present invention;

[0044] Fig.23 A schematic diagram showing a spatial walking example 7 of an embodiment of the present invention;

[0045] Fig.24 A schematic diagram showing a spatial walking example 8 of an embodiment of the present invention;

[0046] Fig.25 A schematic diagram of a spatial walking example 9 according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0047] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, Figures 1 to 25 As shown, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementations. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0048] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0049] Figure 1 A schematic block diagram showing the structure of a computer device according to an embodiment of the present invention. Figure 2 FIG. 1 is a schematic flow chart of a method for implementing visual-spatial ability assessment based on non-immersive virtual reality for a computer device according to an embodiment of the present invention. Figure 1 and Figure 2As shown, the method for implementing visual-spatial ability assessment based on non-immersive virtual reality is used in a computer device, and the computer device includes: a mouse, a display screen, an eye tracker, a jaw rest, a memory, a processor, and a computer program stored in the memory and executable on the processor; wherein the mouse is used to control the movement of the cursor on the display screen, the display screen is used to display the test content corresponding to the method for implementing visual-spatial ability assessment, the eye tracker is used to record the eye movement trajectory of the subject when responding to the corresponding test content, and the jaw rest is used to stabilize the subject's head to ensure that the subject's head does not swing significantly during the assessment process, so as to achieve the purpose of obtaining high-quality eye movement data. The processor is used to implement the method for implementing visual-spatial ability assessment when executing the computer program; the method for implementing visual-spatial ability assessment includes:

[0050] Step S10: after receiving the instruction to enter the path learning, the path learning interface is displayed through the display screen, so that the subject can perform the path learning; wherein, a two-dimensional plane map is displayed on the path learning interface; the two-dimensional plane map is distributed with crisscrossing streets, and the blocks surrounded by the streets are distributed with buildings; the two-dimensional plane map is marked with a prescribed path along the streets, one end of the prescribed path is marked as the starting point, and the other end of the prescribed path is marked as the end point, and there are several crossroads distributed on the prescribed path; the prescribed path is the walking path that the subject needs to follow when accepting the test of walking in the three-dimensional virtual space later; when the subject performs the path learning, the subject starts to memorize the prescribed path until receiving the instruction to end the path learning; wherein, the crossroad is a decision point;

[0051] Step S20: after receiving the instruction to enter the space to walk, a virtual three-dimensional space is displayed on the display screen for the subject to perform the three-dimensional virtual space walking test; wherein the virtual three-dimensional space is the three-dimensional stereoscopic version of the two-dimensional plane map; when the subject performs the three-dimensional virtual space walking test, the subject uses the mouse to make a decision to start from the starting point and walk along the street to the end point according to the specified path remembered, and makes a decision to move forward, turn left, turn right, or turn around at each intersection along the way, until the mouse makes a decision to reach the end point;

[0052] Step S30: After receiving the instruction to return from the space, the subject uses the mouse to start from the end point and move along the street to the starting point according to the specified path in memory, and makes decisions to move forward, turn left, turn right, and turn around at each intersection along the way, until the mouse makes a decision to reach the starting point;

[0053] Step S40: using the eye movement trajectory and mouse movements of the subject recorded by the eye tracker to record and calculate the subject's evaluation index;

[0054] Step S50: Obtaining an evaluation result of the subject's visual-spatial ability according to the subject's evaluation index.

[0055] In this embodiment, non-immersive virtual reality technology is an emerging technology, and its virtual scene is provided to users by creating an ideal window-like virtual environment with the help of computer peripherals such as mouse, keyboard, microphone, etc., through the screen or actual scene data obtained by photography technology plus part of the computer-generated environment. The advantage of non-immersive virtual reality technology is that users are relatively free, and many users can enter the system at the same time.

[0056] In this embodiment, the method for evaluating visual-spatial ability based on non-immersive virtual reality mainly includes three steps: path learning, spatial walking, and spatial return. The method for evaluating visual-spatial ability based on non-immersive virtual reality provided by the present invention provides visual stimulation to the subject while recording the non-subjective conscious response of the subject by using eye movement technology. Specifically, we designed the detection paradigms of [path learning], [spatial walking] and [spatial return] to evaluate the visual-spatial ability of people of different age groups or subjects with different cognitive function levels, realizing a visual-spatial test in the true sense. The importance of the present invention is incomparable to the currently used "paper-pencil" experimental paradigm.

[0057] In a specific embodiment, the first item of the visual-spatial ability assessment method is path learning. Enter the [Path Learning] interface. The interface displays a two-dimensional plane map. There are crisscrossing streets on the map, and the blocks composed of streets have residential areas, schools, hospitals, supermarkets and other buildings. There is a red line along the street on the map. One end of the red line is marked as the "starting point" and the other end is marked as the "end point". This red line is a prescribed path, which is the walking path that the subject needs to follow when performing the second item [Spatial Walking]. The subject needs to memorize this prescribed path. There is no time limit for the learning process. After the subject believes that he is familiar with and remembers the prescribed path, he can perform the second item [Spatial Walking] test. Further, the second item of the visual-spatial ability assessment method is walking in a three-dimensional virtual space. After entering the [Spatial Walking] interface, a virtual three-dimensional space is displayed on the display screen. It is a three-dimensional stereoscopic of the two-dimensional plane map in the [Path Learning] interface. The subject needs to start from the "starting point" and walk along the street to the "end point" according to the prescribed path remembered. The subject can use the mouse to make decisions on moving forward, turning left, turning right, or turning around (backward) at each intersection until reaching the "end point". Among them, each intersection is a decision point where the subject needs to make decisions on moving forward, turning left, turning right, or turning around by using the mouse. Furthermore, the third item of the visual-spatial ability assessment method is the return in the three-dimensional virtual space. After the subject reaches the "end point" from the "starting point" in the [spatial walking] test, the [spatial return] test can be started. The subject needs to follow the specified path in the two-dimensional plane map, starting from the "end point" and returning to the "starting point". Furthermore, the step of obtaining an evaluation result of the subject's visual-spatial ability based on the subject's evaluation index specifically includes: judging whether the subject's evaluation index falls within a preset evaluation index range; the preset evaluation index range is: the evaluation index range of elderly subjects (over 60 years old) or the evaluation index range of young subjects (under 30 years old); when it is determined that the subject's evaluation index falls within the evaluation index range of elderly subjects, it is concluded that the subject's visual-spatial ability is equivalent to that of the elderly; when it is determined that the subject's evaluation index falls within the evaluation index range of young subjects, it is concluded that the subject's visual-spatial ability is equivalent to that of the young.

[0058] In one embodiment of the present invention, the evaluation index of the subject includes one of the following or a combination thereof: the time to complete path learning, the number of focus points on plane buildings during path learning, the total time of looking at plane buildings during path learning, the total time of completing three-dimensional virtual space walking, the segmented time of completing three-dimensional virtual space walking, the number of focus points on spatial buildings during three-dimensional virtual space walking, the total time of looking at spatial buildings during three-dimensional virtual space walking, the number of decision errors during three-dimensional virtual space walking, the path deviation ρ of three-dimensional virtual space walking, the total time of completing three-dimensional virtual space return, the segmented time of completing three-dimensional virtual space return, the number of focus points on spatial buildings during three-dimensional virtual space return, the total time of looking at spatial buildings during three-dimensional virtual space return The number of focus points on the two-dimensional buildings, the total time of looking at the spatial buildings during the three-dimensional virtual space return process, the number of decision errors during the three-dimensional virtual space return process, and the path deviation ε of the three-dimensional virtual space return; wherein, the time to complete the path learning is: the time length between receiving the instruction to enter the path learning and receiving the instruction to end the path learning; the number of focus points on the plane buildings during the path learning process is: the number of focus points on the buildings on the two-dimensional plane map where the subject's gaze stays for more than 150 milliseconds during the path learning; the total time of looking at the plane buildings during the path learning process is: the number of focus points on the buildings on the two-dimensional plane map where the subject's gaze stays for more than 150 milliseconds during the path learning The total time of completing the three-dimensional virtual space walking is: the time length of the mouse walking from the starting point to the end point during the test of the subject's three-dimensional virtual space walking; the segmented time length of completing the three-dimensional virtual space walking is: the time length of the mouse reaching the N+1th decision point from the Nth decision point during the test of the subject's three-dimensional virtual space walking; N is a positive integer greater than or equal to 1; the number of focus points of the spatial buildings during the three-dimensional virtual space walking is: the number of focus points of the buildings in the three-dimensional virtual space where the subject's gaze stays for more than 150 milliseconds during the test of the subject's three-dimensional virtual space walking; the number of focus points of the buildings in the three-dimensional virtual space where the subject's gaze stays for more than 150 milliseconds during the three-dimensional virtual space walking The total time of looking at the spatial building is: the total time that the subject's gaze stays on the focus point on the building in the three-dimensional virtual space during the test of the subject's three-dimensional virtual space walking; the number of wrong decisions during the three-dimensional virtual space walking process is: the number of wrong decisions made by the subject during the test of the subject's three-dimensional virtual space walking; the path deviation ρ of the three-dimensional virtual space walking is: the degree of deviation between the subject's real walking path in the three-dimensional virtual space and the prescribed path during the test of the subject's three-dimensional virtual space walking; the total time to complete the three-dimensional virtual space return is: the length of time it takes for the mouse to return from the end point to the starting point during the test of the subject's three-dimensional virtual space return;The segmented duration of completing the three-dimensional virtual space return is: the length of time taken by the mouse to reach the M-1 decision point from the Mth decision point in the test of the three-dimensional virtual space return; M is a positive integer greater than or equal to 2; the number of focus points of the three-dimensional virtual space return process is: the number of focus points of the three-dimensional virtual space buildings that the subject's eyes stay on for more than 150 milliseconds in the test of the three-dimensional virtual space return; the total time of the three-dimensional virtual space return process is: the total time of the focus points of the three-dimensional virtual space buildings that the subject's eyes stay on in the three-dimensional virtual space in the test of the three-dimensional virtual space return; the number of decision errors in the three-dimensional virtual space return process is: the number of wrong decisions made by the subject in the test of the three-dimensional virtual space return; the path deviation ε of the three-dimensional virtual space return is: the degree of deviation between the subject's real return path in the three-dimensional virtual space and the reverse path of the prescribed path in the test of the three-dimensional virtual space return. ;

[0059] In this embodiment, the real walking path of the subject in the three-dimensional virtual space is: the walking path that the subject walks in the three-dimensional virtual space using a mouse.

[0060] In one embodiment of the present invention, the calculation process of the path deviation ρ of the three-dimensional virtual space walking specifically includes: marking the decision point sequence of the specified path as X = [x1, x2, ..., x n ]; where x i is the i-th decision point on the prescribed path; wherein n is the total number of decision points on the prescribed path; the decision point sequence of the subject's real walking path in the three-dimensional virtual space is marked as Y = [y1, y2, ..., y m ]; where y j is the jth decision point on the actual walking path; wherein m is the total number of decision points on the actual walking path; according to the decision point sequence of the specified path and the decision point sequence of the actual walking path, an n×m dimension distance matrix D is constructed; wherein the element d(i,j) of the distance matrix D is the decision point x of the specified path i To the decision point y of the actual walking path jThe absolute value of the distance between them; a cumulative distance matrix C is constructed from the distance matrix D; wherein the element c(i,j) of the cumulative distance matrix C is the element d(i,j) of the distance matrix D plus the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C; the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y j The minimum cumulative distance between two points; the value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the subject's actual walking path in the three-dimensional virtual space and the prescribed path; when the subject's actual walking path is completely consistent with the prescribed path, the path deviation ρ of the three-dimensional virtual space walking is zero.

[0061] In one embodiment of the present invention, the calculation process of the path deviation ε returned by the three-dimensional virtual space specifically includes: the reverse path of the prescribed path is opposite to the prescribed path of space walking, that is, the decision point sequence of the reverse path of the prescribed path is recorded as X =[ x n , x n-1 ,…, x1 ];in, x i is the first i decision points; wherein n is the total number of decision points on the reverse path of the prescribed path; the decision point sequence of the real return path of the subject in the three-dimensional virtual space is marked as Y =[y m ,y m-1 ,…,y 1 ]; where y j is the jth decision point on the actual return path; wherein m is the total number of decision points on the actual return path; according to the decision point sequence of the reverse path of the specified path and the decision point sequence of the actual return path, a distance matrix of dimension n×m is constructed D ; Wherein, the distance matrix D The element d(i,j) is the decision point x of the reverse path of the prescribed path. i To the decision point y of the true return path j The absolute value of the distance between D Construct a cumulative distance matrix C ; Wherein, the cumulative distance matrix C The element c(i,j) is the distance matrix D The element d(i,j) plus the cumulative distance matrix CThe minimum value among the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y j The minimum cumulative distance between two points; the value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the subject's actual return path in the three-dimensional virtual space and the reverse path of the prescribed path; when the subject's actual return path in the three-dimensional virtual space is completely consistent with the reverse path of the prescribed path, the deviation ε of the path returned in the three-dimensional virtual space is zero.

[0062] In this embodiment, the path deviation ε of the three-dimensional virtual space return is: the degree of deviation between the subject's real return path in the three-dimensional virtual space and the reverse path of the prescribed path when the subject is testing the three-dimensional virtual space return. The calculation process of the path deviation ε of the three-dimensional virtual space return is similar to the calculation process of the path deviation ρ of the three-dimensional virtual space walking. The difference is that the reverse path of the prescribed path is opposite to the prescribed path of space walking. When the subject's real return path in the three-dimensional virtual space is completely consistent with the reverse path of the prescribed path, the path deviation ε of the three-dimensional virtual space return is zero.

[0063] The technical solution of the present invention will be demonstrated below with a specific embodiment 1.

[0064] Example 1

[0065] Subjects:

[0066] In order to verify the evaluation effect of the present invention, 60 subjects were recruited to participate in the experiment. The subjects of the youth group under 30 years old were from schools; the subjects of the elderly group over 60 years old were from ordinary community residents and grassroots workers, etc. The information of each age group is shown in Table 1.

[0067] The inclusion criteria for the subjects participating in this experiment are as follows: (1) normal daily life and social interaction skills; (2) education level of junior high school or above; (3) no major physical illness and eye disease that affects vision (including color blindness); (4) the subjects should have sufficient cognitive and language abilities to complete the neuropsychological assessment; (5) can correctly understand the experimental significance of this study and have good compliance; (6) voluntarily join this study. The exclusion criteria for volunteers participating in this experiment are as follows: (1) with a history of mental illness; (2) brain trauma; (3) suffering from eye disease that affects vision.

[0068] Table 1 Subject information

[0069]

[0070] Ethical Statement:

[0071] This study adhered to the principles of the Declaration of Helsinki and was evaluated and approved by the Research Ethics Committee of China Medical University (No. 202373). All study participants read the research notice and signed the informed consent form before participating in the study. All participants were verbally informed of the overall purpose of this experiment and agreed to participate.

[0072] Experimental design and experimental steps:

[0073] The subjects sat steadily in front of the cognitive function testing instrument, placed their chin on the chin rest of the instrument, and tried to keep their heads still during the test.

[0074] Click [Video Demo] to learn how to take the test. Use the [Practice] mode to learn the content of the test and to get familiar with the use of the mouse. The 2D map in the [Practice] mode is different from the content in the subsequent formal test. The subject can practice three times.

[0075] In this test, if Figure 3 As shown in the figure, the red line is the route that the subject must follow in the subsequent [Space Walk] test. The two-dimensional map of [Path Learning] designs a path with six intersections: three intersections require left turns, two intersections require right turns, and one intersection requires straight driving. There is no time limit for the [Path Learning] process. After the subject believes that he has memorized the path, he can apply to the staff to enter the [Space Walk] test.

[0076] In the [Spatial Walking] part of this test, the subjects were required to follow the prescribed path memorized in [Path Learning] from the “starting point” (such as Figure 4 ) reaches the "end point" (as shown) Figure 6 As shown in Figure 5 As shown, at each intersection, the subject needs to use the mouse to make a decision of "turn left", "turn right" or "go straight".

[0077] Statistical analysis:

[0078] The results of this experiment are expressed as mean ± standard deviation. The homogeneity of variance and normality of the data were tested using the Shapiro-Wilk and Levene methods. If the samples obeyed the normality test and the variance was homogeneous, the comparison between multiple groups was performed using ANOVA and Buffonni test. If the data did not obey the normal distribution and the variance homogeneity test, the Kruskal-Wallis one-way ANOVA test and the Mann-Whitney test with Buffonni correction were used for comparison between multiple groups. Statistical analysis was performed using Origin 2022 software, and the difference was considered statistically significant when P < 0.05.

[0079] Experimental results:

[0080] In the traditional Mini-Mental State Examination, the methods for testing visual-spatial function include time and space orientation test, imitation drawing, immediate memory and recall. Table 2 shows the test results of the MMSE scale. As shown in Table 2, the specificity and sensitivity of the MMSE scale for distinguishing the visual-spatial ability of subjects in two different age groups are very low.

[0081] Table 2 MMSE scale test results

[0082]

[0083] The test results of the present invention on the subjects of these two different age groups are shown in Table 3.

[0084] Table 3 Test results of the present invention

[0085]

[0086]

[0087] Furthermore, if Figure 7 As shown, the total time to complete path learning for young subjects was significantly shorter than that for elderly subjects.

[0088] Furthermore, if Figure 8 As shown in Figure 2, the number of focus points of young subjects in path learning on the two-dimensional map is significantly less than that of elderly subjects. These focus points have the following characteristics: young subjects are mostly concentrated on the prescribed path and intersections (such as Figure 9a ), while the elderly subjects' attention was more scattered (as shown in Figure 9b shown).

[0089] Furthermore, if Fig.10 As shown, young subjects focused on points on the two-dimensional map for significantly shorter periods of time than older subjects.

[0090] Furthermore, if Fig.11 As shown, the time taken by young subjects to complete “spatial walking” in three-dimensional space is shorter than that of elderly subjects.

[0091] Furthermore, if Fig.12 As shown, young subjects paid less attention to spatial scene landmarks during "spatial walking" than older subjects.

[0092] Furthermore, if Fig.13 As shown, young subjects paid less attention to spatial scene landmarks during "spatial walking" than older subjects.

[0093] Furthermore, if Fig.14 As shown, during the "spatial walking" process, the deviation between the actual path and the prescribed path of the young subjects was significantly smaller than that of the elderly subjects.

[0094] Furthermore, if Fig.15 As shown in the figure, subgroup 1: can complete the spatial walking completely according to the prescribed route (ρ = 0.0); subgroup 2: can complete the spatial walking completely according to the prescribed route, but there are slight errors in the intermediate process; subgroup 3: cannot complete the walking completely according to the prescribed route. It can be seen that the actual path of the vast majority of young subjects did not deviate from the prescribed path (subgroup 1), while the actual walking path of the vast majority of elderly subjects deviated significantly from the prescribed path (subgroups 2 and 3).

[0095] Furthermore, if Fig.16 As shown, the distribution of the first errors made by young and elderly subjects during the "spatial walking" process shows that the intersection where elderly subjects are most likely to make errors is the third intersection.

[0096] Furthermore, in the [Space Walking] test, the inconsistency between the actual path and the prescribed path of the subjects can be clearly represented by the quantitative path deviation.

[0097] a) If Fig.17 As shown, Example 1 (ρ = 0.00);

[0098] b) If Fig.18 As shown, Example 2 (ρ = 1.00);

[0099] c) If Fig.19 As shown, Example 3 (ρ = 3.41);

[0100] d) If Fig. 20 As shown, Example 4 (ρ = 4.24);

[0101] e) If Fig.21 As shown, Example 5 (ρ = 3.41);

[0102] f) Fig. 22 As shown, Example 6 (ρ = 12.48);

[0103] g) If Fig.23 As shown, Example 7 (ρ = 2.00);

[0104] h) If Fig.24 As shown, Example 8 (ρ = 4.00);

[0105] i) Such as Fig.25 As shown, Example 9 (ρ=2.00).

[0106] in conclusion:

[0107] The method for evaluating visual-spatial ability based on non-immersive virtual reality of the present invention can effectively identify the differences in visual-spatial ability (path learning, spatial walking) of the subjects, and the results are far better than the evaluation methods of existing scales. Therefore, the method for evaluating visual-spatial ability based on non-immersive virtual reality of the present invention can be used to accurately and comprehensively evaluate visual-spatial ability, one of the dimensions of cognitive function.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for evaluating visual-spatial ability based on non-immersive virtual reality, for use in a computer device, the computer device comprising: A mouse, a display screen, an eye tracker, a jaw rest, a memory, a processor, and a computer program stored in the memory and executable on the processor; wherein the mouse is used to control the movement of a cursor on the display screen, the display screen is used to display the test content corresponding to the method for assessing visual-spatial ability, the eye tracker is used to record the eye movement trajectory of the subject when responding to the corresponding test content, the jaw rest is used to stabilize the subject's head, and the processor is used to implement the method for assessing visual-spatial ability when executing the computer program; characterized in that the method for assessing visual-spatial ability comprises: Step S1: after receiving the instruction to enter the path learning, the path learning interface is displayed through the display screen, so that the subject can perform the path learning; wherein, a two-dimensional plane map is displayed on the path learning interface; the two-dimensional plane map is distributed with crisscrossing streets, and the blocks surrounded by the streets are distributed with buildings; the two-dimensional plane map is marked with a prescribed path along the streets, one end of the prescribed path is marked as the starting point, and the other end of the prescribed path is marked as the end point, and there are several crossroads distributed on the prescribed path; the prescribed path is the walking path that the subject needs to follow when accepting the test of walking in the three-dimensional virtual space later; when the subject performs the path learning, the subject starts to memorize the prescribed path until receiving the instruction to end the path learning; wherein, the crossroad is a decision point; Step S2: after receiving the instruction to enter the space to walk, a virtual three-dimensional space is displayed through the display screen, so that the subject can perform the three-dimensional virtual space walking test; wherein the virtual three-dimensional space is the three-dimensional stereoscopic version of the two-dimensional plane map; when the subject performs the three-dimensional virtual space walking test, the subject uses the mouse to make a decision to start from the starting point and walk along the street to the end point according to the specified path remembered, and makes a decision to move forward, turn left, turn right, or turn around at each intersection along the way, until the mouse makes a decision to reach the end point; Step S3: using the eye movement trajectory of the subject and the movement of the mouse recorded by the eye tracker to record and calculate the evaluation index of the subject; Step S4: Obtaining an evaluation result of the visual-spatial ability of the subject according to the evaluation index of the subject.

2. The method for evaluating visual-spatial ability based on non-immersive virtual reality according to claim 1, characterized in that: After step S2 and before step S3, the method further includes: After receiving the instruction to enter the space and return, the subject uses the mouse to start from the end point and move along the street to the starting point according to the specified path in memory, and makes decisions to move forward, turn left, turn right, and make a U-turn at each intersection along the way until the mouse decides to reach the starting point.

3. The method for evaluating visual-spatial ability based on non-immersive virtual reality according to claim 2, characterized in that: The evaluation index of the subject includes one of the following or a combination thereof: the time to complete path learning, the number of focus points of the plane building during the path learning process, the total time of looking at the plane building during the path learning process, the total time to complete the three-dimensional virtual space walking, the segmented time to complete the three-dimensional virtual space walking, the number of focus points of the space building during the three-dimensional virtual space walking, the total time of looking at the space building during the three-dimensional virtual space walking, the number of decision errors during the three-dimensional virtual space walking, the path deviation ρ of the three-dimensional virtual space walking, the total time to complete the three-dimensional virtual space return, the segmented time to complete the three-dimensional virtual space return, the number of focus points of the space building during the three-dimensional virtual space return, the total time of looking at the space building during the three-dimensional virtual space return, the number of decision errors during the three-dimensional virtual space return, and the path deviation ε of the three-dimensional virtual space return; The duration of completing the path learning is: the time length between receiving the instruction to enter the path learning and receiving the instruction to end the path learning; The number of focus points on the two-dimensional buildings during the path learning process is: the number of focus points on the buildings on the two-dimensional plane map where the subject's gaze stays for more than 150 milliseconds during the path learning process; The total duration of fixating on the planar building during the path learning process is: the total time that the subject's gaze stays on the focus point on the building on the two-dimensional plane map during the path learning process; The total duration of completing the three-dimensional virtual space walking is: the length of time taken by the mouse to walk from the starting point to the end point during the test of the subject performing the three-dimensional virtual space walking; The segment duration for completing the three-dimensional virtual space walking is: the length of time taken by the mouse to reach the N+1th decision point from the Nth decision point during the test of the three-dimensional virtual space walking of the subject; N is a positive integer greater than or equal to 1; The number of focus points of the spatial buildings during the three-dimensional virtual space walking process is: the number of focus points of the buildings in the three-dimensional virtual space where the subject's gaze stays for more than 150 milliseconds during the three-dimensional virtual space walking test; The total duration of fixation on the spatial building during the three-dimensional virtual space walking process is: the total time that the subject's gaze stays on the focus point on the building in the three-dimensional virtual space during the test of the three-dimensional virtual space walking; The number of wrong decisions during the three-dimensional virtual space walking process is: the number of wrong decisions made by the subject during the three-dimensional virtual space walking test; The path deviation ρ of the three-dimensional virtual space walking is: the degree of deviation between the actual walking path of the subject in the three-dimensional virtual space and the prescribed path during the test of the subject's three-dimensional virtual space walking; The total time to complete the three-dimensional virtual space return is: the length of time it takes for the mouse to return from the end point to the starting point during the test of the subject performing the three-dimensional virtual space return; The segment duration for completing the three-dimensional virtual space return is: the length of time taken by the mouse to reach the M-1 decision point from the Mth decision point during the test of the subject's three-dimensional virtual space return; M is a positive integer greater than or equal to 2; The number of focus points of the spatial buildings during the three-dimensional virtual space return process is: the number of focus points of the buildings in the three-dimensional virtual space where the subject's gaze stays for more than 150 milliseconds during the three-dimensional virtual space return test; The total duration of fixation on the spatial building during the three-dimensional virtual space return process is: the total time that the subject's gaze stays on the focus point on the building in the three-dimensional virtual space during the three-dimensional virtual space return test; The number of wrong decisions during the three-dimensional virtual space return process is: the number of wrong decisions made by the subject during the three-dimensional virtual space return test; The path deviation ε of the three-dimensional virtual space return is: the degree of deviation between the subject's actual return path in the three-dimensional virtual space and the reverse path of the prescribed path during the test of the subject's three-dimensional virtual space return.

4. The method for evaluating visual-spatial ability based on non-immersive virtual reality according to claim 3, characterized in that: The calculation process of the path deviation ρ of the three-dimensional virtual space walking specifically includes: The decision point sequence of the specified path is marked as X = [x1, x2, ..., x n ]; where x i is the i-th decision point on the prescribed path; wherein n is the total number of decision points on the prescribed path; The decision point sequence of the subject's real walking path in the three-dimensional virtual space is marked as Y = [y1, y2, ..., y m ]; where y j is the jth decision point on the actual walking path; where m is the total number of decision points on the actual walking path; According to the decision point sequence of the prescribed path and the decision point sequence of the actual walking path, a distance matrix D of dimension n×m is constructed; wherein the element d(i, j) of the distance matrix D is the decision point x of the prescribed path. i To the decision point y of the actual walking path j The absolute value of the distance between them; A cumulative distance matrix C is constructed from the distance matrix D; wherein the element c(i,j) of the cumulative distance matrix C is the element d(i,j) of the distance matrix D plus the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C; the minimum value of the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y j The minimum cumulative distance between two points; The value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the subject's actual walking path in the three-dimensional virtual space and the prescribed path; When the actual walking path of the subject is completely consistent with the prescribed path, the path deviation ρ of the three-dimensional virtual space walking is zero.

5. The method for evaluating visual-spatial ability based on non-immersive virtual reality according to claim 3, characterized in that: The calculation process of the path deviation ε returned by the three-dimensional virtual space specifically includes: The reverse path of the prescribed path is opposite to the prescribed path of space walking, that is, the decision point sequence of the reverse path of the prescribed path is recorded as X =[ x n , x n-1 ,…, x1 ];in, x i is the first i decision points; wherein n is the total number of decision points on the reverse path of the prescribed path; The decision point sequence of the subject's real return path in the three-dimensional virtual space is marked as yes Y =[y m ,y m-1 ,…,y 1 ]; where y j is the jth decision point on the true return path; wherein m is the total number of decision points on the true return path; According to the decision point sequence of the reverse path of the specified path and the decision point sequence of the real return path, a distance matrix of dimension n×m is constructed. D ; Wherein, the distance matrix D The element d(i,j) is the decision point x of the reverse path of the prescribed path. i To the decision point y of the true return path j The absolute value of the distance between them; By the distance matrix D Construct a cumulative distance matrix C ; Wherein, the cumulative distance matrix C The element c(i,j) is the distance matrix D The element d(i,j) plus the cumulative distance matrix C The minimum value among the elements {c(i-1,j),c(i,j-1),c(i-1,j-1)} in the cumulative distance matrix C is x i With y j The minimum cumulative distance between two points; The value of the element c(n,m) in the cumulative distance matrix C is the degree of deviation between the actual return path of the subject in the three-dimensional virtual space and the reverse path of the prescribed path; When the actual return path of the subject in the three-dimensional virtual space is completely consistent with the reverse path of the prescribed path, the deviation ε of the return path in the three-dimensional virtual space is zero.

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