Post 298 –by Gautam Shah
We perceive movements in many different conditions and context. By perception of movements we understand the direction and speed of elements in a situation. Perception of movement is basically a visual process but other sensory faculties aid it. We use our eyes to perceive things aided by movement of eyeballs, eyes, facial and body movement and shift. We also use flickering -fast closing-opening of eyelids to perceive the movement. We use mental process of recollection to judge, if there was any change in comparison to a past event. Movements are perceived in reference to something, a context.
We perceive movements of physical objects, metaphysical entities or effects, and of our own body. Perception of movement is also accompanied by other responses, such as facial and body realignment or orientation, heightened perception of the same happening by other sensorial faculties, and movement of the self towards or away from the object in motion.
The perceptions of movement modalities are different in various beings. The eyes of lower animals respond selectively to what is of important for survival. The retina does not carry out much processing. The condition with higher animals is more complex, the brain responds with sets of movement-detector cells for each direction across the field of view. Human visual experience is constructed by movement detectors that exist in the brain. Each of the retinas has a central zone for perceiving colour and pattern, and a peripheral zone for catching general characteristics of the adjunct visual field. The outer section, on sensing a motion activates (by slight shifting) the core part to take cognizance of it.
There are many different conditions where we observe motion. Simplest perception is of moving object within nominal field of view against static field. A slightly more composite scene is where several objects are moving, each at different speed and direction, and one is able to deduce a general flow and its speed.
When a person in a stationary train observes, through a window (a field that cuts off surroundings) another train, start moving, one feels own train in motion. The observer and the object both moving in same direction (e.g. two trains) may seem to be a non or very slow moving, whereas when moving in opposite directions the apparent speed is enhanced.
People often report that an isolated point of light in a dark room is moving, when it is not. Similar situations arise when we observe movement without a static frame reference, such as watching a star through a telescope, where a star seems to be moving. When a rotating electric fan is illuminated by a flashing light source (called a stroboscope) At certain speed the fan blades seem to be non-moving. An illuminated size reducing object in a dark background seems receding.
A movement effect is created by serially blinking lights (of decoration) that give manifestation of movement. When we watch a movie, we are perceiving motion instead of static images due to blinking of eye or image refreshing rates.
While walking up a curved street in spite of very keen observation, one may not find it familiar, when walking down the same street, because the convex and concave curvilinear natures give different sense of direction and apparent sense of speed.
Camera capturing a street view at faster speed, creates a visual abhorrence or anomaly. Similarly motion can be captured by moving a camera closer to the object, moving the object closer to the camera, and by varying the focus of the lens. In each case the perception as projected is different.