Perception Basics
What is perception?
Using our senses and previous knowledge to understand the world.
What part of the brain first processes visual information?
The primary visual cortex in the occipital lobe.
What is figure-ground perception?
Separating a distinct object (figure) from the background (ground).
Which theory says we recognize objects by matching them to stored patterns?
The template approach.
Which process starts with raw sensory input?
Bottom-up processing.
What is object (pattern) recognition?
Identifying a complex stimulus and seeing it as separate from the background.
What is iconic memory?
A brief visual sensory memory that holds an image after it disappears.
What is an ambiguous figure-ground relationship?
When the figure and ground can switch, creating two possible images.
Which theory says we recognize objects by their distinctive features?
Feature-analysis theory.
Which process uses memory and expectations?
Top-down processing.
What is the difference between distal and proximal stimuli?
Distal stimulus is the real object in the environment; proximal stimulus is the image on the retina.
Why can we recognize objects even when the proximal stimulus is incomplete?
Because the brain relies on shape and past knowledge to fill in missing information
What are illusory contours?
Edges we perceive even though they are not physically present.
What are geons in the recognition-by-components theory?
Simple 3-D shapes that combine to form objects.
Why can we read scrambled sentences?
Because top-down processing uses context to fill in missing letters and words.
What type of information does the proximal stimulus provide to the brain?
Sensory information registered by receptors, such as the image on the retina.
What pathway does visual information follow from the eye to the brain?
From the retina through neurons along the visual pathway to the visual cortex.
Why do we experience ambiguous figures?
Because neurons adapt and the brain alternates between two reasonable interpretations.
Why is the template approach considered weak today?
Because it cannot explain how we recognize objects in many different forms.
When is top-down processing especially strong?
When stimuli are ambiguous or shown very briefly.
Why does perception depend on previous knowledge?
Because the brain uses memory and experience to interpret incomplete or unclear sensory input.
Why is the primary visual cortex not the only area involved in perception?
Because recognizing complex objects requires additional brain regions beyond basic visual processing.
Why does the brain create illusory contours?
Because early visual neurons respond to them and the brain tries to make sense of incomplete stimuli.
How does recognition-by-components explain complex object recognition?
By showing that objects are recognized as combinations of simple 3-D shapes (geons).
What are “smart mistakes” in perception?
Errors that happen when the brain makes the most likely guess based on context.