Mammals can throw and catch {Throwing and Catching}.
Animal Motions
Animals can move in direction, change direction, turn around, and wiggle. Animals can move faster or slower. Animals move over horizontal ground, climb up and down, jump up and down, swim, dive, and fly.
Predators and Prey
Predators typically intercept moving prey, trying to minimize separation. In reptiles, optic tectum controls visual-orientation movements used in prey-catching behaviors. Prey typically runs away from predators, trying to maximize separation. Animals must account for accelerations and decelerations.
Gravity and Motions
Animals must account for gravity as they move and catch. Some hawks free-fall straight down to surprise prey. Seals can catch thrown balls and can throw balls to targets. Dogs can catch thrown balls and floating frisbees. Cats raise themselves on hind legs to trap or bat thrown-or-bouncing balls with front paws.
Mammal Brain
Reticular formation, hippocampus, and neocortex are only in mammals. Mammal superior colliculus can integrate multisensory information at same spatial location [O'Regan and Noë, 2001]. In mammals, dorsal vision pathway indicates object locations, tracks unconscious motor activity, and guides conscious actions [Bridgeman et al., 1979] [Rossetti and Pisella, 2002] [Ungerleider and Mishkin, 1982] [Yabuta et al., 2001] [Yamagishi et al., 2001].
Allocentric Space
Mammal dorsal visual system converts spatial properties from retinotopic coordinates to spatiotopic coordinates. Using stationary three-dimensional space as fixed reference frame simplifies trajectories perceptual variables. Most motions are two-dimensional rather than three-dimensional. Fixed reference frame separates gravity effects from internally generated motions. Internally generated motion effects are straight-line motions, rather than curved motions.
Human Throwing and Shooting
Only primates can throw, because they can stand upright and have suitable arms and hands. From 45,000 to 35,000 years ago, Homo sapiens and Neanderthal Middle-Paleolithic hunter-gatherers cut and used wooden spears. From 15,000 years ago, Homo sapiens Upper Paleolithic hunter-gatherers cut and used wooden arrows, bows, and spear-throwers. Human hunter-gatherers threw and shot over long trajectories.
Human Catching
Geometric Invariants: Humans can catch objects traveling over long trajectories. Dogs and humans use invariant geometric properties to intercept moving objects.
Trajectory Prediction: To catch baseballs, eyes follow ball while people move toward position where hand can reach ball. In the trajectory prediction strategy [Saxberg, 1987], fielder perceives ball initial direction, velocity, and perhaps acceleration, then computes trajectory and moves straight to where hand can reach ball.
Acceleration Cancellation: When catching ball coming towards him or her, fielder must run under ball so ball appears to move upward at constant speed. In the optical-acceleration-cancellation hypothesis [Chapman, 1968], fielder motion toward or away from ball cancels ball perceived vertical acceleration, making constant upward speed. If ball appears to vertically accelerate, it lands farther than fielder. If it appears to vertically decelerate, it lands shorter. Ball rises until caught, because baseball is always above horizon, far objects are near horizon, and near objects are high above horizon.
Transverse Motion: Fielder controls transverse motion independently of radial motion. When catching ball toward right or left, fielder moves transversely to ball path, holding ball-direction and fielder-direction angle constant.
Linear Trajectory: In linear optical trajectory [McBeath et al., 1995], when catching ball to left or right, fielder runs in a curve toward ball, so ball rises in optical height, not to right or left. Catchable balls appear to go straight. Short balls appear to curve downward. Long balls appear to curve upward. Ratio between ball elevation and azimuth angles stays constant. Fielder coordinates transverse and radial motions. Linear optical trajectory is similar to simple predator-tracking perceptions. Dogs use the linear optical trajectory method to catch frisbees [Shaffer et al., 2004].
Optical Acceleration: Plotting optical-angle tangent changes over time, fielders appear to use optical-acceleration information to catch balls [McLeod et al., 2001]. However, optical trajectories mix fielder motions and ball motions.
Perceptual Invariants: Optical-trajectory features can be invariant with respect to fielder motions. Fielders catch fly balls by controlling ball-trajectory perceptions, such as lateral displacement, rather than by choosing how to move [Marken, 2005].
1-Consciousness-Sense-Vision-Physiology-Motion
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Date Modified: 2022.0225