Space Perception and Binocular Vision, Lecture notes of Psychology

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Space Perception and

Binocular Vision

Chapter 6 Space Perception and Binocular Vision

Monocular Cues to Three-Dimensional Space

Binocular Vision and Stereopsis

Combining Depth Cues

Development of Binocular Vision and Stereopsis

Introduction

Euclidian geometry: Parallel lines remain parallel as they are extended in space.

• Objects maintain the same size and shape as they move around in space.
• Internal angles of a triangle always add up to 180 degrees, etc.

Introduction

Notice that images projected onto the retina are non-Euclidean!

• Therefore, our brains work with non- Euclidean geometry all the time, even though we are not aware of it.

Introduction

Probability summation: The increased probability of detecting a stimulus from having two or more samples.

• One of the advantages of having two eyes that face forward.

Introduction

Binocular summation: The combination (or “summation”) of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone.

The two retinal images of a three- dimensional world are not the same!

Introduction

Binocular disparity: The differences between the two retinal images of the same scene.

• Disparity is the basis for stereopsis, a vivid perception of the three- dimensionality of the world that is not available with monocular vision.

Introduction

Depth cue: Information about the third dimension (depth) of visual space.

Monocular depth cue: A depth cue that is available even when the world is viewed with one eye alone.

Binocular depth cue: A depth cue that relies on information from both eyes.

Figure 6.3 Comparing rabbit and human visual fields (Part 2)

• Figure 6.4 M. C. Escher, Relativity ,

Figure 6.5 Occlusion makes it easy to infer relative position in depth

Figure 6.6 Figure 6.5 could be an “accidental” view of the pieces shown here in (a). It is much more likely, however, that it is a generic view of circle, square, and triangle, as shown in ( b )

Monocular Cues to Three-Dimensional Space

Relative size: A comparison of size between items without knowing the absolute size of either one.

• All things being equal, we assume that smaller objects are farther away from us than larger objects.

Figure 6.7 This is a photograph of a collection of Plasticine balls that are resting on the same surface at the same distance from the camera