Advanced Principles of Psychology - Lecture 9

Flashcards on the Story of 3D Object and Space Perception

Physicalist Approach

Examining a physical image and determining the “features” in a physical image that might be associated with 3D perception.

Cue-based approach

An approach to 3D perception.

Linear Weighted Averaging

A method of combining different cues to estimate depth.

Depth Cues (Artists)

Contour, Shading, Interposition, Relative Size, Height in the Field, Texture, Perspective, Blur.

Depth Cues (Scientists)

Binocular Disparity and Motion Parallax.

Perceptual Judgments

Depth, Distance, Size, Shape, Orientation.

Linear Weighted Averaging (Mixing Model)

Combines depth & distance cues (physical description of the retinal image and extra-retinal information).

Binocular Disparity (Picture)

With pictures, disparities are negligible, but binocular disparities are present due to the picture itself; disparity cue says everything is flat (depth = 0).

LWA Prediction (Binocular Viewing)

3D space and object shape in the picture should appear flattened or distorted compared to what the pictorial cues are specifying.

LWA Prediction (Monocular Viewing)

Increase in perceived magnitude of depth under monocular viewing of a picture compared to binocular viewing.

Monocular-Aperture Viewing

Viewing an image through an aperture with one eye.

Problems with LWA

Predictions for perceived magnitude of depth comparing binocular and monocular (or monocular aperture) viewing do not match results from psychophysics.

Visual Duality

Seeing a 3D space in the picture at the same time as perceiving the picture itself as a flat surface.

Monocular Stereopsis

The perception of depth and 3-dimensionality is enhanced when viewing images with one eye, especially through an aperture.

Phenomenology

Sense of “real” separation in depth between things, sense of things “coming out of the picture,” feeling you can reach out and touch things giving rise to an overall feeling of “visual realness”.

LWA Limitations

LWA does not explain differences in phenomenology that occur even when the magnitude of perceived depth remains unchanged.

Egocentric Distance

Impression of how far away things are in terms of being able to walk to them or reaching out to them.

Relative Depth (Unscaled Depth)

Perceiving 3D shape and layout without perceiving the actual distances or sizes.

Exocentric Distances (Scaled Structure)

Observer sees objects at specific distances, apprehends the actual size of objects and the configuration (i.e., apprehends the scale).

Loomis et al., 1992 Study

Demonstrated a dissociation between perceived ambulatory distance (accurate) and judged distance between two points (inaccurate).

Ambulatory Distances

encode distance perception separately.

Theoretical proposal

3D space and object perception entails three distinct forms of spatial phenomenology including egocentric distance, relative depth structure, and exocentric distances.

Relative (unscaled) depth

3D shape and layout. The distance to the objects is unknown, i.e. X is unknown.

Exocentric Distances (Scaled Structure)

requires implicit knowledge of the egocentric distance to the object or configuration.

Depth cues

Contour, Shading, Interposition, Relative Size, Height in the Field, Texture, Perspective, Blur, Binocular disparity, Motion Parallax.

Distance Cues (near space)

Accommodation, Convergence, Depth of Focus Blur.

Distance Cues (far space)

Declination from eye level, Ground Plane information.

Distance cues (extra-retinal cues)

Lens accommodation (0.5m), Ocular convergence angle (2m), Declination from eye level (5m-20m).