agnosia is an inability to recognize visual objects that is a function neither of general intellectual loss nor of loss of basic sensory abilities. 
agnosia is a severe deficit in the ability to perceive sensory information, usually related to the visual sensory modality; agnosics have normal sensations but lack the ability to interpret and recognize what they sense, usually as a result of lesions in the brain
binocular depth cues are one of the two chief means of judging the distances of visible objects 
bottom-up processing is Information from the physical stimulus is used to help recognize a stimulus. Contrast with top-down processing. 
bottom-up theories are theoretical explanations of perception, which focus on the physical stimulus being perceived and then proceed upward to consider higher order cognitive processes
constructive perception is one of the two key views of perception (also termed intelligent perception; cf. direct perception); asserts that the perceiver builds the stimulus that is perceived, using senso~ information as the foundation for the structure, but also considering the existing knowledge and thought processes of the individual
depth is as applied to perception, the perceived distance of something from the body of the perceiver
direct perception is one of two key views of perception which asserts that the array of information in the sensory receptors is all that is needed for an individual to perceive anything and that prior knowledge or thought processes are not necessary for perception
figure-ground is a Gestalt principle of form perception: the tendency to perceive that an object in or an aspect of a perceptual field seems prominent, whereas other objects or aspects recede into the background
Gestalt approaches to form perception is a way of studying the perception of objects and other forms, based on the notion that the whole of a form differs from the sum of its individual parts
gestalt principles of organization are the principles that determine how a scene is organized into components. 
Gestalt psychology is school of psychological thought, which asserts that many psychological phenomena must be understood as integral wholes and that analysis into fragmentary elements often destroys the integrity of these phenomena
law of Pragnanz is a Gestalt principle asserting the perceptual tendency to perceive visual arrays in ways that most simply organize disparate elements into a stable and coherent form
monocular depth cues are one of the two chief means of judging the distances of visible objects, based on sensed information that can be represented in just two dimensions and observed with just one eye
percept is mental representation of a stimulus that is perceived
perception is the set of psychological processes by which people recognize, organize, synthesi:e, and give meaning (in the brain) to the sensations received from environmental stimuli (in the sense organs)
perceptual constancy is the perception that a given object remains the same even when the immediate sensation of the object changes
prototype is a model that best represents a given concept (and various instances of the concept); the model for a given concept comprises a set of characteristic features that tend to be typical of most examples of the concept, although no single characteristic feature is necessary for a given example to be considered an instance of the concept
receptor is one of two types of neurons; receives information about sensations throughout the body as a first step toward transmission of that information to the brain, usually through the spinal cord
recognition-by-components theory is Biederman's proposal that we recognize objects by first identifying the geons that correspond to their subobjects. 
template is exact model of a distinctive pattern or form, used as the basis for perception of patterns or form
template matching is a theory of pattern recognition which claims that an object is recognized as a function of its overlap with various pattern templates. 
top-down processing is Information from the general context is used to help recognize a stimulus. Contrast with bottom-up processing. 
top-down theories are theoretical explanations of perception that focus on the high-level cognitive processes, existing knowledge, and prior expectations that influence perception, and then work their way down to considering the sensory data, such as the perceptual stimulus