CHAPTER 3:PERCEPTION3.1 Introduction•Illusion of clarity – an example:oA grid placed over a blocky image makes the image appear clearer than the same image without the grid. But a grid placed on a high-resolution image decreases clarity.•Visual Agnosia: The eyes are fine but unable to recognize what is seen.oBut visual recognition is not always completely impaired.oImpaired recognition only applies to vision. Patients can identify objects through other sense like touch.•Associative Agnosia: A form of visual agnosia. Patients can’t recognize objects even though they can reproduce the objects by drawing them.•Time Spaces:The perceptual experience of time units such as days of the week or months of the year as occupying spatial locations outside of the body.oThis experience is automatic, goes with them wherever they go, and cannot be consciously inhibited.•Perception: Processing sensory information such that it produces a meaningful understanding of the information.•Stimulus: An entity in the external environment that can be perceived by an observer.3.2 Perception as a Function of the Environment•Theory of Ecological Optics – Gibson:oPerception involves directly absorbing the visual information present in the environment.•Ambient Optical Array (AOA) (Gibson):oAll the visual information that is present at a particular point of view.oGibson said that every different viewing point has a unique pattern of light that enters the eyes.oGibson thought that perception was accomplished mostly by the sensory organs.•Texture Gradients: Gradual changes in the pattern of a surface that is normally assumed to be uniform, which provides information about the surface characteristics such as whether the surface is receding or curved.•Topological Breakage:The discontinuity created by the intersection of two texture gradients.oA useful indicator for the edges of objects.•Scatter-reflection: The degree to which light scatters when reflected from a surface.oHow light scatters from objects tells us a lot about the nature of the object’s surface.•Gibson thinks that the problem with classical theories of perception is that they relied on assumptions of a fixed, monocular perspective. But, with illusions as an example, the moment you allow an observer to move about, the illusion vanishes.•Transformation: The change of optical information hitting the eye when the observer moves.•Optic Flow Field:The movement of objects or of the observer through the environment produces changes in what is seen.
oWhen you look out the front windshield while driving, the objects straight in front of you appear stationary but those at the edge move faster.3.3 Pattern Recognition•Differs from Gibson’s theories in 2 ways:oTheories of pattern recognition do not consider the complex array of light information reflecting from all surfaces and objects.