Perception Chapter 5
What is Perception?
Organization of information to make it useful
Psychophysical Approach
Psychophysics – behavioral aspects of a response to stimuli
Difference threshold – degree of change in a stimulus necessary for a person to detect the difference
Psychophysical Approach
Signal-detection theory - sensitivity to stimuli Physical condition Motivation Mood Attitude
Perceptual Constancies
Our brain becomes a storehouse of knowledge about details Size, shape and
color Memories play a role
in interpreting new stimuli
Four Constancies
1. Size 2. Shape 3. Brightness 4. Color
Perceptual Organization
Constructionist ViewThe brain
constructs a perception out of many individual sensations
Gestalt Psychologists
Max Wertheimer Whole is more
important than the sum of the parts
Each part affects every other
Gestalt Laws of Perception
1. Law of Proximity – tendency to group things together that are close to one another
Gestalt Laws of Perception
2. Law of Similarity – group things together that have some visual element in common, such as size, shape, or color.
Gestalt Laws of Perception
3. Law of Continuation – tendency to see interrupted lines as continuous lines
Gestalt Laws of Perception
4. Law of Closure – Tendency to fill in missing details to complete a figure
Figure and Ground
3 Principles 1. The figure is more “thinglike” and more
memorable than the ground 2. The figure is seen as being in front of the
ground 3. The ground is seen as unformed material and
seems to extend behind the figure
Bodily Depth Cues
Monocular cues – one eye Binocular cues – two eyes 1. Accommodation – change in the shape of
the lens that varies with distance (1 eye) 2. Convergence – the way the eyes rotate
inward and outward with changes in distance (2 eyes)
3. Binocular disparity – difference between the images provided by each eye
Pictorial Depth Cues
Monocular cues Give a two-
dimensional painting, photograph, or movie the illusion of depth where none exists.
Pictorial Depth Cues
1. Linear perspective – parallel lines appear to converge as they move away from you
2. Relative size – objects that are known to be the same size will convey depth if one is smaller than the other
3. Relative height – objects that are higher in a scene are usually perceived as being more distant
Pictorial Depth Cues
4. Overlap – a sensation of depth is created when one object partially blocks another
5. Texture – changes in texture can convey depth
6. Atmospheric (aerial)- distant objects tend to look less sharp than close objects
7. Relative motion – objects that are close to the car seem to be moving by quickly, while objects in the distance appear to move slowly
Perception of Motion
Different kinds of movement: A figure moving against a stationary background Objects at rest against a moving background Objects moving at different speeds in relation to
each other Observer’s own movements in relation to his/her
surroundings Induced movement
perception of movement of an object that is not moving
Illusions
Muller-Lyer Illusion
Which line appears longer?
Illusions
Ponzo Railroad Track Illusion Which of the two horizontal
lines on the track appear longer?
Illusions
The Necker Cube The cubes seem to
shift and another side seems closer to you.
Then it shifts back again
Illusions
The Boring Figure Designed by
E.G. Boring Ambiguous figure Young girl/old
woman
Illusions
The Ames Room Albert Ames Appears to be a normal
room Actually shaped so the
left corner is almost twice as far from the viewer as the right corner
The viewer perceives the nearer person as being much larger than the other, although both are exactly the same height
Illusions
What do you see?
Illusions
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