Week 6: PSYC 236: Object Perception, Recognition, and Visual Brain Pathways

Flashcards based on PSYC 236 lecture notes covering object perception, Gestalt rules, Marr and Biederman's theories, visual brain pathways, specialized regions, and neurological agnosias.

Inverse Projection Problem

The challenge where a given two-dimensional image cast onto the retina can be created by an infinite number of different three-dimensional objects.

Translation Invariance

The capacity of the visual system to recognize an object regardless of its location or position within the field of view.

Accidental View

A specific viewpoint that produces a visual image containing a feature or alignment that does not regularly exist in the three-dimensional object itself.

Figure-Ground Segregation

The perceptual process of separating a visual scene into a primary object of focus (the figure) and the background behind it (the ground).

Border Ownership

The perceptual principle stating that a shared boundary between a figure and background belongs exclusively to the figure, defining its shape and making it appear in front.

Gestalt Rules

A set of visual perception principles describing how the brain naturally organizes isolated elements into structured wholes based on rules like proximity, similarity, common fate, good continuation, closure, common region, and connectedness.

Raw Primal Sketch

The initial stage in David Marr's model of vision that organizes 2D light intensities to identify basic visual features like edges, bars, terminators, and blobs.

2.5D Sketch

A viewer-centered stage in David Marr's model of visual processing that represents the orientation and depth layout of visible object surfaces relative to the observer.

3D Model Representation

An object-centered, viewer-independent stage in David Marr's vision model that describes the solid 3D shape of an object, maintaining shape constancy across different viewpoints.

Geons

Geometric ions proposed by Irving Biederman as fundamental 3D volumetric building blocks (such as cylinders, blocks, wedges, and cones) used to recognize complex objects.

Ventral Stream

The visual processing pathway extending from primary visual cortex (V1) to the temporal lobe, specialized for object identification and recognition ("What" pathway).

Dorsal Stream

The visual processing pathway extending from primary visual cortex (V1) to the parietal lobe, specialized for spatial location, motion perception, and visually guided action ("Where" pathway).

Lateral Occipital Complex (LOC)

A region in the visual cortex that responds strongly to perceived object shapes and forms compared to random or unstructured textures.

Inferotemporal (IT) Cortex

An area in the ventral visual pathway containing neurons with large receptive fields that respond selectively to complex object categories and shapes.

Grandmother Cell Concept

A theoretical hypothesis proposing that a single highly specific neuron fires exclusively in response to a specific, highly familiar stimulus such as a particular face.

Fusiform Face Area (FFA)

A specialized region located in the fusiform gyrus of the temporal lobe that selectively responds to human faces.

Extrastriate Body Area (EBA)

A specialized area in the visual cortex that responds selectively to images of human bodies and body parts other than faces.

Parahippocampal Place Area (PPA)

A functional region of the visual cortex that responds selectively to visual scenes, landscapes, and spatial environments.

Visual Word Form Area (VWFA)

A functional brain area located predominantly in the left hemisphere near the FFA that responds selectively to written words and letters.

Agnosia

A neurological deficit characterized by the inability to perceive or recognize specific sensory features or objects, unrelated to primary sensory loss or general dementia.

Apperceptive Agnosia

A form of visual agnosia where a patient cannot perceive, organize, or copy basic visual structures and shapes, despite being able to draw objects from memory.

Associative Agnosia

A form of visual agnosia where a patient can accurately perceive and copy visual structures, but cannot assign meaning or recognize what the object is.

Prosopagnosia

A neurological impairment characterized by the inability to recognize familiar human faces, which can be acquired through brain damage (such as lesions to the FFA) or present congenitally.

Hemispatial Neglect

A neurological attention deficit usually caused by damage to the right temporo-parietal junction, causing a patient to ignore or neglect the left side of space.

Akinetopsia

A rare condition known as motion blindness, typically resulting from parietal or MT/V5 damage, where a patient loses the conscious ability to perceive continuous visual motion.

Optic Ataxia

A neurological disorder resulting from dorsal stream damage where a patient cannot accurately reach for, point to, or grasp objects under visual guidance despite intact visual object perception.

Perception-Action Model Double Dissociation

The neuropsychological double dissociation demonstrated by Goodale and Milner showing that ventral stream damage (Patient DF) impairs perception while sparing action, whereas dorsal stream damage (Patient RV) spares perception while impairing action.