general psychology (py110) chapter 3 sensation and perception

General Psychology General Psychology (PY110)(PY110)

Chapter 3

Sensation and Perception

Windows on the WorldWindows on the World

Our sensory neurons (receptors) are constantly bombarded with stimuli

We understand the world through our senses, our “windows” on the world

Our reality, in fact, is dependent upon two processes:◦Sensation: Gathering information◦Perception: Interpreting information (a

process)

Stimulus – Sensation – Stimulus – Sensation – PerceptionPerception

Examples of Examples of MisperceptionMisperception

Bottom-up Processing and Bottom-up Processing and Top-down ProcessingTop-down Processing

Bottom-up processing is the processing of sensory information as it enters the sensory structures and travels to the brain

Top-down processing is the brain’s use of existing knowledge, beliefs, and expectations to interpret the sensory stimulation◦ Perception is subjective because of top-down

processing◦ Perceptual set occurs when we interpret an

ambiguous stimulus in accordance with our past experiences

◦ A contextual effect occurs when we use the present context of sensory input to determine its meaning

Perceptual Organization Perceptual Organization and Top-down Processingand Top-down Processing

A Context Effect on A Context Effect on PerceptionPerception

Illusion Vs HallucinationIllusion Vs Hallucination

Stimulus Interpretation Response Perception

StimulusMisinterpretati

onResponse Illusion

No Stimulus

Misinterpretation

Response Hallucination

Perception

Illusion

Hallucination

Misinterpretation can be caused by

Perceptual OrganizationPerceptual Organization

Gestalt means “organized whole”◦Gestalt psychologists believe that the

organized whole is greater than the sum of its individual pieces of sensory information

◦The figure-and-ground principle states that the brain organizes sensory input into a figure (the center of attention) and a ground (the background)

An Example of An Example of Figure-Ground AmbiguityFigure-Ground Ambiguity

An Example of An Example of Figure-Ground AmbiguityFigure-Ground Ambiguity

Both purses do the same job… Right?

So they should cost about the same… Right?

Gestalt Principles of Gestalt Principles of OrganizationOrganization

Similarity-objects similar are considered a unit

Proximity-because of spacing objects considered a unit

Closure- the tendency to fill in the gap to produce a familiar object

SimilaritySimilarity

Does this furniture go together?

ProximityProximityWhat do you see?

Did you interpret the closeness of these two people as evidence of a relationship?

ClosureClosure

Do you see the white triangle?

What is this?

What about this?

An Example of an An Example of an Organizational Perceptual Organizational Perceptual AmbiguityAmbiguity

Perceptual ConstancyPerceptual ConstancyRefers to the perceptual stability

of◦Size – Football player◦Shape - Nickel◦Brightness - Coal◦Color - Coca-Cola

For familiar objects seen at ◦Varying distances◦Different angles◦Different lighting conditions

Perceptual Constancy - Perceptual Constancy - ColorColor

Can this really taste

the same as this?

Perceptual Constancy - Perceptual Constancy - SizeSize

Even though they look like ants from our seats…

We know how big they really are

Perceptual Constancy - Perceptual Constancy - ShapeShape

We know that both of theseballs are actually the same shape because our experience tells us

how a football is shaped

Visual IllusionsVisual Illusions

In the Ponzo illusion, two horizontal lines are equal in length, but one appears longer than the other

The convergence of the two lines (i.e., linear perspective) outside the horizontal lines normally indicates increasing distance

Visual IllusionsVisual Illusions

In the Müller-Lyer illusion, two vertical line segments are equal in length, but the one with arrow feather endings appears to be longer

The line with arrow feather endings has the appearance of a corner that is receding away from you (the corners where two walls meet in a room), while the line with arrowhead endings has the appearance of a corner that is jutting out toward you (the corners where two sides of a building meet)

Thus, it is our past experience with corners that leads the brain to believe that the line with arrow feather endings is farther away

Examples of a Visual Examples of a Visual IllusionIllusion

Summary of PerceptionSummary of Perception

general psychology (py110) chapter 3 sensation and perception

Documents

sensory structures

sensory stimulationperception

backgroundan example

ground ambiguityboth

colafor familiar objects

ground principle states

objects similar

interpreting information