Visual Perception and Depth Perception – Lecture Flashcards

A comprehensive set of QUESTION_AND_ANSWER flashcards derived from the supplied lecture notes on visual perception, depth cues, Gestalt principles, processing streams, and perceptual disorders.

Where are electrochemical messages sent to initiate visual perception, and what is their role?

The occipital lobes; they are responsible for the initial processing of information into visual perception.

Describe the visual information pathway from the retina to the cortex.

Optic nerves from each retina project to the thalamus and then to the primary visual cortex in the occipital lobe.

Where do signals from the right visual field go after crossing at the optic chiasm?

They are transmitted to the left hemisphere (signals from the right visual field go to the left hemisphere and vice versa).

What are the three levels of visual processing and their functions?

Primary visual areas (lower-level tasks; cortical blindness if damaged); Secondary visual areas (seeing objects, color, movement); Tertiary visual areas (higher tasks like reading and arithmetic).

What are feature detectors in the visual system?

Neurons in the visual cortex that respond to specific visual features (e.g., horizontal lines, vertical lines, color, shape, motion); many fire together to form an image.

List the five properties of a cognitive module as proposed by Fodor.

Encapsulates information; domain-specific; mandatory operation; innate; operates an input or output process.

Who are Hubel and Wiesel and what did they discover about the visual cortex?

David Hubel and Torsten Wiesel; they discovered that cortical cells respond to lines and edges rather than just spots of light, revealing orientation-selective feature detectors.

How do cortical neurons respond to different line orientations (vertical, horizontal, diagonal)?

Vertical lines elicit rapid firing; horizontal lines often elicit little or no response; diagonal lines elicit moderate firing—orientation-selective responses.

Which brain lobes process the 'What?' and 'Where?' aspects of vision?

Temporal lobe processes 'What?' (object identity); Parietal lobe processes 'Where?' (location and spatial relations).

What does parsing mean in perceptual organization?

Working out which elements go together in a scene.

What is perceptual expectancy (perceptual set)?

A bias to perceive stimuli in a particular way based on prior knowledge or context; can influence interpretation of ambiguous images.

What is figure-ground organization?

Distinguishing the central figure from the background.

What is a reversible figure and how can perceptual set influence it?

An image that can be seen in two different ways; perceptual set can cause the interpretation to shift between the alternatives.

What is perceptual constancy and what are its main types?

The tendency to perceive objects as unchanging in colour, shape, and size despite changes in viewpoint; types include colour constancy, shape constancy, and size constancy.

What are depth cues and how are they categorized?

Depth cues help perceive 3D; categorized into binocular cues (require both eyes) and monocular cues (require one eye).

What are binocular depth cues and examples?

Retinal disparity and convergence.

What are monocular depth cues and examples?

Linear perspective, patterns of light and shadow, relative size, motion parallax (also overlap and texture gradient).

What is linear perspective in depth perception?

Parallel lines appear to converge as they recede into the distance.

What is relative height as a depth cue?

Objects lower in the visual field are perceived as nearer than those higher up, given the same size.

What is texture gradient as a depth cue?

Surfaces appear rougher up close; texture becomes denser with distance.

What is interposition (overlap) as a depth cue?

Nearer objects overlap or occlude those that are further away.

What is atmospheric (aerial) perspective?

Distant objects appear bluer and less distinct due to scattering of light in the atmosphere.

What is the Moon illusion and why does it occur?

The Moon appears larger on the horizon than overhead due to depth cues affecting perceived distance.

What is monocular movement parallax?

As the head moves, closer objects move faster in the opposite direction, while farther objects move slower or with the head’s movement.

What are the two broad processing routes in visual perception, and how do they differ?

Top-down processing uses context and expectations; bottom-up processing uses sensory data from the stimulus. Both are used in perception.

What is a perceptual hypothesis?

An initial guess about how a stimulus pattern should be organized; a part of top-down processing.

What is the Phi phenomenon?

The illusion of movement produced by presenting visual stimuli in rapid succession.

Name some Gestalt principles of perceptual organization.

Proximity, Similarity, Continuity, Closure, Common region, Contiguity; (Simplicity is also often cited).

What are visual illusions?

Perceptions that do not correspond to the actual properties of the physical stimulus due to misinterpretation of signals.

What is the Muller-Lyer illusion?

An optical illusion where lines of the same length appear different due to the addition of arrow-like fins.

What is the Horizontal-Vertical illusion?

A perceptual phenomenon where vertical lines are perceived as longer than horizontal lines of the same length.

What are perceptual illusions related to impossible figures?

Images that appear to depict a real object but cannot exist in three-dimensional space; they challenge normal perception.

What is a visual illusion test about eye movement and motion perception?

Certain images appear to move when viewed in specific patterns or afterfixation; movement is induced by processing dynamics of the visual system.

What are perceptual deficits called, and which major types are mentioned?

Agnosias; major types include visual object agnosia and prosopagnosia (face blindness).

What are the two systems for object recognition and their general hemispheric associations?

Two routes: a holistic/face-object route (often right hemisphere) and an analytic/parts route (often left hemisphere). The diagram also notes strong associations with faces (right FFA) and words (left angular gyrus).

What is alexia and where is the typical brain damage located?

Reading problems due to brain damage, typically involving the left angular gyrus.

What is prosopagnosia and where is the typical brain damage located?

Face recognition impairment, typically associated with the right fusiform face area (FFA).

What is apperceptive agnosia?

A failure in visual perception with intact visual sensation; difficulty segmenting complex pictures, recognizing objects from unusual angles, or copying.

What is associative agnosia?

The inability to name objects despite being able to describe or copy them after seeing them; often linked to posterior cerebral artery damage.