We do not perceive the world how it really is, but as it is useful for us to perceive it.

The process of organizing and interpreting information we get from our senses
• enables us to recognize meaningful objects and events.
In transforming sensations into perceptions, we create the meaning

• Any moment we focus our awareness on only a limited aspect of all that we experience
• Example– directions video

• Ability to attend selectively to only one voice among many

The dominance of vision over other sense modalities, such that what is felt or heard conforms to what is seen.

• Once we have attended to certain stimuli, how do we organize them into meaningful perceptions?

• Dalmatian Picture

Perceptual Illusions

Perceptual Illusions

Perceptual Illusions

Perceptual Illusions

Perceptual Illusions

• When vision competes with other senses, vision usually wins- known as visual capture
• For example- watching a movie, in theatres we believe the sound is coming from the screen where people are talking, when really, it’s not

• To transform sensory information into meaningful perceptions, we must organize it
• We must perceive objects as distinct from their surroundings, see them as having a meaningful and constant form, and discern their distance and motion.

• German scientist became intrigued with how the mind organizes sensations into perceptions
• Given a cluster of sensations, the human perceiver organizes them into a gestalt
• Described principles by which we organize our senses into perceptions

Gestalt Psychology
• Gestalt means “an organized whole”
• These psychologists were concerned with how and why we GROUP objects together.
• They stated that humans can not help but perceive stimuli in groups rather than individual or isolated elements
This explains why we see a cube and not a set of isolated holes or circles

Perceptual Organization: Gestalt
 Grouping
 the perceptual tendency to organize stimuli into coherent groups
 Grouping Principles
 proximity --group nearby figures together
 similarity --group figures that are similar
 continuity --perceive continuous patterns
 closure --fill in gaps
 connectedness --spots, lines, and areas are seen as unit when connected

Perceptual Organization:
Grouping Principles

• We group nearby figures together.

• Grouping nearby figures together
3 sets of parallel lines not six separate lines

• Figures similar to each other we group together.

• Grouping together figures that are similar to each other
9 separate shapes
Or
Two columns and one
Column?

• We perceive smooth, continuous patterns rather than discontinuous ones

• Perceiving smooth continuous patterns not discontinuous ones

• When they are uniform and linked, we perceive spots, lines, or areas as a single unit

Perceptual Organization:
Closure
 We fill in gaps to create a complete, whole object

• Filling in gaps to create a complete, whole object

 Figure and Ground-organization of the visual field into objects (figures) that stand out from their surroundings (ground)

1. What is perception?
2. Give an example of bottom-up processing
3. Explain Gestalt Psychology and give one example of grouping.
4. Explain Cocktail Party Effect

Our perceptions are affected by the biology of our sensory systems, but also by our previous experiences and cultural expectations.
Or in other words our…

Take a moment to write down a few adjectives to describe each person based on their pictures.
A B

Perception is also often based on…
 Perceptual Set
 A bias to perceive one thing and not another when looking at things in our world
 Sort of the same thing as a mental set
 So in some ways it can cause us to make errors in judgments when we are trying to perceive the world through our senses

What do you see?
• What you see in the center is influenced by your perceptual set

Bill Clinton and who?

Which is the real Madonna?

• When we hold the eyes as a constant it is difficult to identify the correct Madonna. Now that the image is rotated it is easy to tell the difference.


Used to reveal how we normally organize and interpret sensations

Optical or Visual Illusions

Discrepancies between the appearance of a visual stimulus and its physical reality

• Figure-Ground
Relationship
• When we look at objects we see the object as the figure and its surroundings as the background
– Airplane in the sky



The ability to see objects in three dimensions although the images that strike the retina are two dimensional.
Allows us to judge distance.

Perceptual Organization
Depth Perception
Visual Cliff
Used to test infants depth perception

How do we transform twodimensional objects to threedimensional perception?

Binocular Cues :
 depth cues that depend on two eyes
•Monocular Cues :
•depth cues that depend on one eye

Perceptual Organization: Depth
 Binocular cues
Perception
 retinal disparity
 images from the two eyes differ
 closer the object, the larger the disparity
 convergence
 neuromuscular cue
 two eyes move inward for near objects

Perceptual Organization: Depth
Perception
 Monocular Cues
 relative size
 smaller image is more distant
 interposition
 closer object blocks distant object
 relative clarity
 hazy object seen as more distant
 texture coarse --> close fine --> distant

Perceptual Organization: Depth
Perception
 Monocular Cues (cont.)
 relative height
 higher objects seen as more distant
 relative motion
 closer objects seem to move faster
 linear perspective
 parallel lines converge with distance
 relative brightness
 closer objects appear brighter

Linear Perspective
Parallel lines seem to converge with distance.

• Relative Size if we know that two objects are similar in size, the one that looks smaller is farther away
Relative Size

Interposition if something is blocking our view, we perceive it as closer

What tools do we use to perceive motion…
 Stroboscopic movement

Perceiving continuous movement

Example
• Movies
Flip Book Example

• An illusion of movement created when two or more adjacent lights blink on and off in succession.

• Definition: an eye disease in which the lens becomes covered in an opaque film that affects sight, eventually causing total loss of sight.

ESP
Three types of ESP:
1. Telepathy- mind to mind communication
2. Clairvoyance- perceiving events as they are taking place
3. Precognition- perceiving future events
Also associated with ESP, psychokinesis (“mind over matter”