4.14 Ventral Stream and Perceptual Constancy

These flashcards cover key concepts related to the ventral stream and its role in perceptual constancy, particularly focused on size constancy and related illusions.

What is perceptual constancy?

Perceptual constancy is our ability to maintain a consistent perception of our environment and objects despite changes in viewing angle, perspective, or lighting conditions.

How do we perceive size constancy?

We perceive size constancy by understanding that objects, like trees, are roughly the same size, even when they appear different due to perspective.

What example illustrates size constancy involving trees?

When looking at trees in a picture, our brain adjusts to understand that they are of similar size despite their differing appearances due to depth cues.

What is the Ponzo illusion?

The Ponzo illusion is the phenomenon where we perceive an object further away, such as a beaver at the top of an image, as larger than a closer object, despite them being the same size.

What basic assumption contributes to the Ponzo illusion?

The assumption is that objects farther away must be larger if they occupy the same retinal space as closer objects.

Give an example of how context affects size perception.

In images where characters recede into the background, they appear larger, impacting our perception of their true size.

What is the Ames room illusion?

The Ames room illusion involves a distorted trapezoidal room that makes people appear to be different sizes based on their position within the room.

How does the Ames room exploit our brain's assumptions?

It exploits the assumption that people occupying a room should appear consistently in relation to the room's dimensions, leading to size misperceptions.

What role do depth cues play in our perception of size constancy?

Depth cues help our brain interpret the size of objects in relation to their distance, contributing to the subjective experience of size constancy.

What effect does removing contextual information have on perception?

Removing contextual information can reveal that objects perceived as different sizes are actually the same size when viewed without depth cues.