Chapter 2 - Basic processes in visual perception Flashcards
Retinal ganglion cells
Retinal cells provide the output signals from the retina
Retinopy
The notion that there is mapping between the receptor cells in the retina and points on the surface of the visual cortex.
Receptive field
The region of the retina in which light influences the activity of a particular neuron.
Lateral inhibition
Reduction of activity in one neuron caused by activity in a neighbouring neuron.
Achromatopsia
A condition caused by brain damage in which there is very limited colour perception but form and motion perception are relatively intact.
Akinetopsia
A brain-damaged condition in which motion perception is severely impaired even though stationary objects are perceived reasonable well.
Binding problem
The issue of integrating different types of information to produce coherent visual perception.
Ventral stream
The part of the visual processing system involved in object perception and recognition and the formation of perceptual representations.
Dorsal stream
The part of the visual processing system most involved in visually guided action.
Allocentric coding
Visual or spatial coding of objects relative to each other.
Egocentric coding
Visual or spatial coding dependent on the position of the observer’s body.
Optic ataxia
A condition in which there are problems making visually guided movements in spite of reasonable intact visual perception.
Visual form agnosia
A condition in which there are severe problems in shape perception (what an object is) but apparently reasonable ability to produce accurate visually guided actions.
Hollow-face illusion
A concave face mask is misperceived as a normal face when viewed from several feet away.
Proprioception
An individual’s awareness of the position and orientation of parts of their body.
Dichromacy
A deficiency in colour vision in which one of three cone classes is missing.
Negative afterimages
The illusory perception of the complementary colour to the one that has just been fixated; green is the complementary colour to red and blue is complementary to yellow.
Colour constancy
The tendency for an object to be perceived as having the same colour under widely varying viewing conditions.
Illuminant
A source of light illuminating a surface or object.
Mutual illumination
The light reflected from the surface of an object impinges on the surface of a second object.
Chromatic adaptation
Changes in visual sensitivity to colour stimuli when the illumination alters.
Monocular cues
Cues to depth that can be used by one eye but can also be used by both eyes together.
Binocular cues
Cues to depth that requires both eyes to be used together.
Oculomotor cues
Cues to depth produced by muscular contractions of the muscles around the eye; use of such cues involves kinaesthesia (also known as the muscle sense).
Texture gradient
The rate of change of texture density from the front to the back of a slanting object.
Motion parallax
A depth cue based on movement in one part of the retinal image relative to another.
Binocular disparity
A depth cue based on the slight disparity in the two retinal images when an observer views a scene; it is the basis for Stereopsis.
Stereopsis
Depth perception based on the small discrepancy in the two retinal images when a visual scene is observed.
Autostereogram
A complex two-dimensional image perceived as three-dimensional when not focused for a period of time.
Amblyopia
A condition in which one eye sends an inadequate input to the visual cortex; informally known as lazy eye.
Vergence
A cue to depth based on the inward focus of the eyes with close objects.
Accommodation
A depth cue based on change in optical power produced by thickening of the eye’s lens when an observer focuses on close objects.
Haptic
Relating to the sense of touch.
Size constancy
Objects are perceived to have a given size regardless of the size of the retinal image.
Ames room
A very distorted room that nevertheless looks normal under certain viewing conditions.
Honi phenomenon
The typical apparent size changes when an individual walks along the rear wall of the Ames room are reduced when female observers view a man to whom they are very close emotionally.
Open-object illusion
The misperception that objects with missing boundaries are larger than objects the same size with boundaries.
Body size effect
An illusion in which misperception of one’s own bodily size causes the perceived size of objects to be misjudged.
Subliminal perception
Perceptual processing occurring below the level of conscious awareness that can nevertheless influence behaviour.
Blindsight
The ability to respond appropriately to visual stimuli in the absence of conscious visual experience in patients with damage to the primary visual cortex.
