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“Ecological foundations of human motion model

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Wangdo Kim
Wangdo Kim

Human movement control is assumed localized in internal structures. In this vein, nerve system controls individual muscle, which is basis of conventional approach. The new approach is rather a process is distributed over the performer and environment system; the interaction from individual and the environment regulates movements through muscle synergy or co-activated muscles.

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Faculty of Human Kinetics Technical University of Lisbon Neuromechanics Research Group Wangdo Kim1,*, Antonio Veloso1, Duarte Araújo3, Maria Machado1, Veronica Vleck2, Liliana Aguiar1, Silvia Cabral1 and Filomena Vieira1 1 Biomechanics Laboratory 2 CIPER (Center for the Interdisciplinary Study of Human Performance) 3Sports Expertise Laboratory Faculty of Human Kinetics Technical University of Lisbon Ecological foundations of human motion model
Movements and postures are controlled and coordinated to realize functionally specific acts based on the perception of affordances (that is, possibilities for action (Gibson 1979) James Jerome Gibson (January 27, 1904– December 11, 1979), was an American psychologist Edward S. Reed (November 20, 1954 - February 14, 1997) was a philosopher of science and an ecological psychologist in the vein of James J. Gibson. Eleanor J. Gibson (December 7, 1910 – December 30, 2002) was an American psychologist
Don Norman: Designing For People PERCEIVED AFFORDANCE " The designer cares more about what actions the user perceives to be possible than what is true " "The Psychology of Everyday Things" (POET: Norman, 1988)
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Aims  To present experimental evidence to support the idea that invariants are, in fact, used by the golfer’s perceptual system.  Golfer’s pickup of invariants can explain the totality of golf swing.  The performer and its environment are co- participants.
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The Niches of the environment  Animals: their movements are animate.  They are not governed by the law of mechanics  A niche referes to how an animal lives  The niche implies a kind of animal  The animal implies a kind of niche  Note the complementarity of the two
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY J.J. Gibson’s Perception  Invariants  Constraint manifolds  Direct Perception  Affordances  Experimental Evidence
As shown in Figure 6, a thin rectangular plate is supported on a frictionless horizontal plane (z = 0) with four circular shaped pegs arranged in configuration (a), (b) and (c). The contact between the plate and the peg is assumed frictionless point contact.Determine the wrench (force/torque) exerted on the plate by the four pegs respectively and write the four wrenches in a 6 x 4 matrix for configuration (a), (b) and (c) respectively. (6 marks) The plate is allowed to move only on the horizontal plane. Based on the configurations of the pegs, determine the directions of the unconstrained instantaneous motion (the directions of the twist motion) of the plate for configuration (a), (b), and (c) respectively, if there is any. x y o 1 2 3 4 x y o a a b b 1 2 3 4 (a)
For case (a), 4 wrenches can only constrain the plate in X- and Y- direction. It cannot constrain the rotation in Z-direction, i.e., the reciprocal twist motion is in [0,0,0,0,0,1]. For case (b), the 4 wrenches can partially constrain the plate in all 3 directions. However, as the peg are arranged in such a way that a twist motion in the CW Z-direction rotation cannot be constrained. This can be reflected in the linear combination of the 4 wrenches that the torque in Z-direction is always positive. For case (c ), the 4 wrenches can fully constrain the plate in 3 directions. Hence, there is no unconstrained twist motion.
"You think too much."
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORYDOF Analysis Example  Individual feature screw representation  Algorithms  Resultant Twistmatrix and Wrenchmatrix  Interpretation 2 2 4 X Y Z x x x y yy zz f2 f1 Taken From [Adams and Whitney 2001]
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORYExample (Cont.) 2 2 4 X Y Z x x x y yy zz f2 f1  Assembly DOF and Constraint Solution F1 1 0 0 2 0 1 0 2 0 0 1 0 0 0 0 1              F2 0 1 0 2 1 0 0 6 0 0 1 0 0 0 0 1                TResultant  0 0 1 2 2 0 WResultant              0 1 0 0 0 2 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0Taken From [Adams and Whitney 2001]
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Singular configuration for the 2D parallel manipulator a linear variety of the set of lines Jean-Pierre Merlet. Singular Configurations of Parallel Manipulators and Grassmann Geometry. The International Journal of Robotics Research 1989; 8; 45 a pair of skew lines : a flat pencil of lines
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY
“Ecological foundations of human motion model
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The generalized problem of degrees of freedom “How can a neuromuscular system with an exorbitant number of degrees of freedom be made to act if it had but one degree of freedom?” Bernstein (1935) (Turvey, 1990) Perception controls behavior by detecting informational constraints specific to goal-paths (Gibson, 1979)−in the nature of laws at the ecological sense.
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY A reciprocal connection LCL 6$ A reciprocal connection scenario compatible with a single DOF of the right knee joint about $. Here the vectors associated with the five constraints $i´ intersect the axis of $. The five intersections are indicated by the markers. In this model, for simplicity, the LCL as indicated is not included. (Kim and Kohles, 2011) The Plenitute hypothesis: Biology makes extra degrees of freedom that may be used to modulate external force by internal forces. (Shaw 1999) are cast in terms of efference be cast in terms of afference
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The knee joint provides the instantaneous screw which is reciprocal to the impulsive ground reaction force . No combination of angular velocity at the will cause instantaneous translational movement, and any force at the ground contact will cause no rotation at . The reaction forces (and torques) of the GRF will then be taken by the structures of the limbs (i.e. the femur is the largest bone) than they would have been taken by joint constraints.   Under the law of mutability, structures are slow function.
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY -10 -8 -6 -4 -2 0 2 4 6 8 10 -60 -40 -20 0 20 40 60 -40 -20 0 20 40 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60 -100 0 100 ISA screws are shown to regularly intersect the GRF wrenches as indicated with the colored lines progressing in time and space (X-direction). Progression of Gait -100 -50 0 50 100 150 200 250 300 350 180 200 220 240 260 280 300 320 340 -500 -400 -300 -200 -100 0 100 200 300 400 X -Y (mm) Z $ $´ X -Y Z Wangdo Kim et al., Measuring Knee Constraints Through Mechanical Reciprocity, Submitted to Medical Engineering & Physics Shank Thigh Relative
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Some Affordances of the terrestrial environment  Locomotion, movement through the environment, is the behavior that most dictates the morphology and physiology of animals  The perception of the ground that is literally the basis of the behavior of land animals
a simple spring-mass system Claire T. Farley Leg stiffness is not directly related to hopping mechanics, but, rather, to the hopping environment.
“Ecological foundations of human motion model
• In a verification purpose for positioning IAK tracking in time-sequence of motion data, the knee ISA screws are shown to nearly coincide with a reciprocal screw of the GRF as indicated in the zoom up pan. This representative analysis indicates a reciprocal connection (close to a special configuration that can exert a wrench of substantial intensity on the corresponding reciprocal screw in the GRF without overloading the knee joint torque).
The one-degree-of-freedom inverted pendulum model K C y m L K = spring constant of the foot/ground interface C = damping coefficient of the foot/ground interface The “extended Kalman filter (EKF)” approach used here for the first time to directly apply measured ground forces Kim, W., Tan, J., Veloso, A., Vleck, V., & Voloshin, A. S. (2011). The natural frequency of the foot-surface cushion during the stance phase of running. Journal of Biomechanics, 44(4), 774-779
55 identification process of combined estimation of both unknown physiological state and mechanical characteristics of the environment in an inverse dynamic model
“Ecological foundations of human motion model
“Ecological foundations of human motion model
“Ecological foundations of human motion model
“Ecological foundations of human motion model
Y Z O MC A Y Z O MC A A pure force A pure translation at A A pure rotation in a principal direction of inertia A pure couple in a principal direction of inertia
“Ecological foundations of human motion model
“Ecological foundations of human motion model
“Ecological foundations of human motion model
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Y X Z X Y Z O MC C f Cτ α aC A T m1 H H I        OM 0.788 0 0 0 29.241 1.001 0 0.788 0 29.241 0 1.108 0 0 0.788 1.001 1.108 0 0 29.241 1.001 2855.908 5.206 123.719 29.241 0 1.108 5.206 2859.116 111.823 1.001 1.108 0 123.719 111.823 20.966                        Due to its special 6×6 form, the screw inertial tensor at ‘O’ =
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The eigenvalue problem provides a unique decomposition of as m1 H 0 0 0 0H J T f T O f m f M m                            
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Detached club (Physical physics)
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY An astonishing behavior to animals with hands Invariants , taken with reference to the golfers (exteroception)
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY X Y Z
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY  : A special line complex is the linear line complex defined by a single twist . Every marker point of the segment has its velocity vector tangential to the helix that passes through it. The pattern of this velocity vector is a helicoidal velocity field. Each marker point that does not coincide with the twist axis of is referred to as a pole. Associated with each pole is its corresponding polar plane. Shown are a polar plane and its corresponding pole as defined by the instantaneous screw axis .  The ISA used to transform the marker set to must be determined form cylindroids . and are two twists of zero pitch on the cylindroid . $ISA pole (marker) polar plane
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Perception and Action as Functional Relationsas :dispositional properties  ‘Perceiving is an achievement of the individual, not an appearance in the theatre of his consciousness. It is a keeping-in-touch with the world, an experiencing of things rather than a having of experiences’ (Gibson, 1979, p. 239).  And we aimed to share in the social world this information as a “genuine” tool for performance variables.  A functional system can manifest itself in different ways, through different assemblages of anatomical substrates.
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY : -100 0 100 200 300 0 50 100 150 -100 -50 0 50 100 150 200 250 300 350 1 Ant Pos Z (cm) Y (cm) X (cm) C Y (cm) X (cm)
1 Ant Pos Y (cm) Z (cm) X (cm) D Y (cm) X (cm) the goal-directedness of behavior is captured
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Equally a fact of environment and a fact of behavior Attached club (Ecological physics) D Y (cm) X (cm) Radius of gyration Club initial position
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Environment (neighborhood) in swing? Niches not yet occupied C Y (cm) X (cm)
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Conclusion  This perception-action coupling manifold, which utilizes correlating alignments of both the generating lines of ISA and e3, can be directly applied to investigate how the novices can perceive the affordances about an effective swing, without an excessive amount of learning (Gibson 1979). "You think too much."
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY
BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The difficulties are of a different kind  James J. Gibson (1979 The ecological approach to visual perception. Boston: Houghton Mifflin) asks us mainly to do is to unlearn.  Our entire education has been geared to making us distrust our sense and slightly to look down on those who confuse their subjective experiences with objective facts.
Thank you! The world is a meaningful environment of an animal.

More Related Content

“Ecological foundations of human motion model

  • 1. Faculty of Human Kinetics Technical University of Lisbon Neuromechanics Research Group Wangdo Kim1,*, Antonio Veloso1, Duarte Araújo3, Maria Machado1, Veronica Vleck2, Liliana Aguiar1, Silvia Cabral1 and Filomena Vieira1 1 Biomechanics Laboratory 2 CIPER (Center for the Interdisciplinary Study of Human Performance) 3Sports Expertise Laboratory Faculty of Human Kinetics Technical University of Lisbon Ecological foundations of human motion model
  • 2. Movements and postures are controlled and coordinated to realize functionally specific acts based on the perception of affordances (that is, possibilities for action (Gibson 1979) James Jerome Gibson (January 27, 1904– December 11, 1979), was an American psychologist Edward S. Reed (November 20, 1954 - February 14, 1997) was a philosopher of science and an ecological psychologist in the vein of James J. Gibson. Eleanor J. Gibson (December 7, 1910 – December 30, 2002) was an American psychologist
  • 3. Don Norman: Designing For People PERCEIVED AFFORDANCE " The designer cares more about what actions the user perceives to be possible than what is true " "The Psychology of Everyday Things" (POET: Norman, 1988)
  • 4. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Aims  To present experimental evidence to support the idea that invariants are, in fact, used by the golfer’s perceptual system.  Golfer’s pickup of invariants can explain the totality of golf swing.  The performer and its environment are co- participants.
  • 5. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The Niches of the environment  Animals: their movements are animate.  They are not governed by the law of mechanics  A niche referes to how an animal lives  The niche implies a kind of animal  The animal implies a kind of niche  Note the complementarity of the two
  • 6. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY J.J. Gibson’s Perception  Invariants  Constraint manifolds  Direct Perception  Affordances  Experimental Evidence
  • 7. As shown in Figure 6, a thin rectangular plate is supported on a frictionless horizontal plane (z = 0) with four circular shaped pegs arranged in configuration (a), (b) and (c). The contact between the plate and the peg is assumed frictionless point contact.Determine the wrench (force/torque) exerted on the plate by the four pegs respectively and write the four wrenches in a 6 x 4 matrix for configuration (a), (b) and (c) respectively. (6 marks) The plate is allowed to move only on the horizontal plane. Based on the configurations of the pegs, determine the directions of the unconstrained instantaneous motion (the directions of the twist motion) of the plate for configuration (a), (b), and (c) respectively, if there is any. x y o 1 2 3 4 x y o a a b b 1 2 3 4 (a)
  • 8. For case (a), 4 wrenches can only constrain the plate in X- and Y- direction. It cannot constrain the rotation in Z-direction, i.e., the reciprocal twist motion is in [0,0,0,0,0,1]. For case (b), the 4 wrenches can partially constrain the plate in all 3 directions. However, as the peg are arranged in such a way that a twist motion in the CW Z-direction rotation cannot be constrained. This can be reflected in the linear combination of the 4 wrenches that the torque in Z-direction is always positive. For case (c ), the 4 wrenches can fully constrain the plate in 3 directions. Hence, there is no unconstrained twist motion.
  • 9. "You think too much."
  • 10. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORYDOF Analysis Example  Individual feature screw representation  Algorithms  Resultant Twistmatrix and Wrenchmatrix  Interpretation 2 2 4 X Y Z x x x y yy zz f2 f1 Taken From [Adams and Whitney 2001]
  • 11. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORYExample (Cont.) 2 2 4 X Y Z x x x y yy zz f2 f1  Assembly DOF and Constraint Solution F1 1 0 0 2 0 1 0 2 0 0 1 0 0 0 0 1              F2 0 1 0 2 1 0 0 6 0 0 1 0 0 0 0 1                TResultant  0 0 1 2 2 0 WResultant              0 1 0 0 0 2 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0Taken From [Adams and Whitney 2001]
  • 12. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Singular configuration for the 2D parallel manipulator a linear variety of the set of lines Jean-Pierre Merlet. Singular Configurations of Parallel Manipulators and Grassmann Geometry. The International Journal of Robotics Research 1989; 8; 45 a pair of skew lines : a flat pencil of lines
  • 15. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The generalized problem of degrees of freedom “How can a neuromuscular system with an exorbitant number of degrees of freedom be made to act if it had but one degree of freedom?” Bernstein (1935) (Turvey, 1990) Perception controls behavior by detecting informational constraints specific to goal-paths (Gibson, 1979)−in the nature of laws at the ecological sense.
  • 17. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY A reciprocal connection LCL 6$ A reciprocal connection scenario compatible with a single DOF of the right knee joint about $. Here the vectors associated with the five constraints $i´ intersect the axis of $. The five intersections are indicated by the markers. In this model, for simplicity, the LCL as indicated is not included. (Kim and Kohles, 2011) The Plenitute hypothesis: Biology makes extra degrees of freedom that may be used to modulate external force by internal forces. (Shaw 1999) are cast in terms of efference be cast in terms of afference
  • 18. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The knee joint provides the instantaneous screw which is reciprocal to the impulsive ground reaction force . No combination of angular velocity at the will cause instantaneous translational movement, and any force at the ground contact will cause no rotation at . The reaction forces (and torques) of the GRF will then be taken by the structures of the limbs (i.e. the femur is the largest bone) than they would have been taken by joint constraints.   Under the law of mutability, structures are slow function.
  • 19. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY -10 -8 -6 -4 -2 0 2 4 6 8 10 -60 -40 -20 0 20 40 60 -40 -20 0 20 40 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60 -100 0 100 ISA screws are shown to regularly intersect the GRF wrenches as indicated with the colored lines progressing in time and space (X-direction). Progression of Gait -100 -50 0 50 100 150 200 250 300 350 180 200 220 240 260 280 300 320 340 -500 -400 -300 -200 -100 0 100 200 300 400 X -Y (mm) Z $ $´ X -Y Z Wangdo Kim et al., Measuring Knee Constraints Through Mechanical Reciprocity, Submitted to Medical Engineering & Physics Shank Thigh Relative
  • 20. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Some Affordances of the terrestrial environment  Locomotion, movement through the environment, is the behavior that most dictates the morphology and physiology of animals  The perception of the ground that is literally the basis of the behavior of land animals
  • 21. a simple spring-mass system Claire T. Farley Leg stiffness is not directly related to hopping mechanics, but, rather, to the hopping environment.
  • 23. • In a verification purpose for positioning IAK tracking in time-sequence of motion data, the knee ISA screws are shown to nearly coincide with a reciprocal screw of the GRF as indicated in the zoom up pan. This representative analysis indicates a reciprocal connection (close to a special configuration that can exert a wrench of substantial intensity on the corresponding reciprocal screw in the GRF without overloading the knee joint torque).
  • 24. The one-degree-of-freedom inverted pendulum model K C y m L K = spring constant of the foot/ground interface C = damping coefficient of the foot/ground interface The “extended Kalman filter (EKF)” approach used here for the first time to directly apply measured ground forces Kim, W., Tan, J., Veloso, A., Vleck, V., & Voloshin, A. S. (2011). The natural frequency of the foot-surface cushion during the stance phase of running. Journal of Biomechanics, 44(4), 774-779
  • 25. 55 identification process of combined estimation of both unknown physiological state and mechanical characteristics of the environment in an inverse dynamic model
  • 30. Y Z O MC A Y Z O MC A A pure force A pure translation at A A pure rotation in a principal direction of inertia A pure couple in a principal direction of inertia
  • 34. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Y X Z X Y Z O MC C f Cτ α aC A T m1 H H I        OM 0.788 0 0 0 29.241 1.001 0 0.788 0 29.241 0 1.108 0 0 0.788 1.001 1.108 0 0 29.241 1.001 2855.908 5.206 123.719 29.241 0 1.108 5.206 2859.116 111.823 1.001 1.108 0 123.719 111.823 20.966                        Due to its special 6×6 form, the screw inertial tensor at ‘O’ =
  • 35. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The eigenvalue problem provides a unique decomposition of as m1 H 0 0 0 0H J T f T O f m f M m                            
  • 36. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Detached club (Physical physics)
  • 37. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY An astonishing behavior to animals with hands Invariants , taken with reference to the golfers (exteroception)
  • 39. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY  : A special line complex is the linear line complex defined by a single twist . Every marker point of the segment has its velocity vector tangential to the helix that passes through it. The pattern of this velocity vector is a helicoidal velocity field. Each marker point that does not coincide with the twist axis of is referred to as a pole. Associated with each pole is its corresponding polar plane. Shown are a polar plane and its corresponding pole as defined by the instantaneous screw axis .  The ISA used to transform the marker set to must be determined form cylindroids . and are two twists of zero pitch on the cylindroid . $ISA pole (marker) polar plane
  • 40. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Perception and Action as Functional Relationsas :dispositional properties  ‘Perceiving is an achievement of the individual, not an appearance in the theatre of his consciousness. It is a keeping-in-touch with the world, an experiencing of things rather than a having of experiences’ (Gibson, 1979, p. 239).  And we aimed to share in the social world this information as a “genuine” tool for performance variables.  A functional system can manifest itself in different ways, through different assemblages of anatomical substrates.
  • 41. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY : -100 0 100 200 300 0 50 100 150 -100 -50 0 50 100 150 200 250 300 350 1 Ant Pos Z (cm) Y (cm) X (cm) C Y (cm) X (cm)
  • 42. 1 Ant Pos Y (cm) Z (cm) X (cm) D Y (cm) X (cm) the goal-directedness of behavior is captured
  • 43. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Equally a fact of environment and a fact of behavior Attached club (Ecological physics) D Y (cm) X (cm) Radius of gyration Club initial position
  • 44. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Environment (neighborhood) in swing? Niches not yet occupied C Y (cm) X (cm)
  • 45. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY Conclusion  This perception-action coupling manifold, which utilizes correlating alignments of both the generating lines of ISA and e3, can be directly applied to investigate how the novices can perceive the affordances about an effective swing, without an excessive amount of learning (Gibson 1979). "You think too much."
  • 48. BIOMECHANICS AND FUNCTIONAL MORPHOLOGY LABORATORY The difficulties are of a different kind  James J. Gibson (1979 The ecological approach to visual perception. Boston: Houghton Mifflin) asks us mainly to do is to unlearn.  Our entire education has been geared to making us distrust our sense and slightly to look down on those who confuse their subjective experiences with objective facts.
  • 49. Thank you! The world is a meaningful environment of an animal.

Editor's Notes