Week 7B – Theories of Visual Perception: Gibson's Ecological Approach and the Constructivist Approach

Flashcards covering vocabulary and core concepts from the lecture on visual perception theories, including Gibson's Ecological Approach and the Constructivist Approach.

Perception (Roth, 1986 definition)

The means by which information acquired from the environment via the sense organs is transformed into experiences of objects, events, sounds, tastes, etc.

Distal stimulus

The actual object or event in the environment that emits or reflects energy.

Proximal stimulus

The energy from the distal stimulus that falls upon the sense organs.

Transduction

The process by which sense organs convert real-world energy (light, sound, etc.) into electrical signals.

Qualia

The internal and subjective component of sense perceptions, such as the perceptual experience of color or pain.

Explanatory gap

The conceptual difficulty in explaining how physical processes in the brain give rise to subjective experiences, such as whether one person's 'Red' is the same as another's.

Gibson’s ecological theory of perception

A bottom-up approach claiming that perception is 'direct' and that the rich information in the environment is sufficient for interaction without complex cognitive processes.

Ambient Optic Array

The structure of light reflected by textured surfaces in the environment, which changes as the observer moves.

Invariants

Unambiguous information about the environment that remains constant and can be directly perceived from the retinal array.

Horizon ratio relation

An invariant where the proportion of an object above and below the horizon line remains constant for objects of the same size on the same ground, regardless of distance.

Texture gradients

An invariant where changes in texture in the optic array provide information about the distance, orientation, and curvature of surfaces.

Gibson & Bridgeman (1987) study

An empirical study where subjects correctly identified properties from black and white photos of surfaces with an average identification accuracy of approximately $67.0\%$.

Motion parallax

A monocular depth cue where nearby objects appear to move rapidly and far objects appear to move slowly as an observer moves relative to a $3$-D scene.

Optic flow

A combination of parallax and retinal size resulting from observer movement that provides information about the environment.

Affordance

Actionable possibilities offered by the environment relative to the organism, such as an object being 'sit-on-able' or 'graspable'.

Action Specific Perception

The concept that what people perceive is dependent upon their current action capabilities.

Warren (1984) Doorway Study

Research showing that doorway passability is judged based on the ratio of aperture width to shoulder width with a threshold of $\sim 1.3\times$.

Warren (1984) Step Study

Research showing that people judge a step as climbable based on a body-scaled ratio of riser height divided by leg length, with a critical ratio of $0.88$.

Proffitt et al. (2003)

A study demonstrating that hills appear steeper to observers when they are tired or encumbered.

Mirror neurons

Neurological evidence for affordances consisting of neurons that fire when an individual is observing actions.

Canonical Neurons

Neurons that respond to objects in terms of potential actions, such as orientation, size, and grasping.

Constructivist approach to perception

The theory that the retinal image is insufficient and perception depends upon stored knowledge, memory, and experience.

Unconscious inference

Hermann von Helmholtz's concept of an involuntary, pre-rational, and reflex-like mechanism that forms visual impressions.

Likelihood principle

A constructivist principle suggesting the brain chooses the most likely interpretation of a retinal image based on stored knowledge.

Perceptual hypotheses

Richard Gregory’s term for the interpretations generated by the brain, which can lead to illusions if inaccurate.

Hollow mask illusion

An illusion explained by the constructivist approach as a result of stored knowledge that faces are convex.

Bottom-up processing

Data-driven processing where perception is built from the sensory information received from the environment.

Top-down processing

Conceptually-driven processing where perception is influenced by higher-level cognitive processes, such as task goals, context, and experience.

Titchner Illusion

An illusion where the brain over-emphasizes size differences when grouping and separating objects.

Marr's information processing theory

A computational approach to perception that views the reconstruction of the environment as an information processing problem.