Perception

1
Perception

• Selective Attention focus of conscious
  awareness on a particular stimulus

2
Testing Selective Attention
3
Perceptual Illusions Ames cube
4
Perceptual Organization

• Remember visual capture concept
• Grouping
• the perceptual tendency to organize stimuli into
  coherent groups
• Gestalt, figure-ground, continuity, etc.

5
Perceptual Organization- Gestalt

• Gestalt- an organized whole
• Turning pieces into big picture (illusory
  contours)
• 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

6
Illusory Contours

• Gestalt Principles
• - an organized whole
• Turning pieces into big picture (illusory
  contours)
• Remember Wertheimer

7
Perceptual Organization- Grouping Principles
8
Perceptual Organization- Gestalt

• Figure-ground perception
• People distinguish between target figure and
  background
• Simplicity
• People tend to perceive the simplest pattern
  possible

9
Perceptual Recognition

• How do we recognize things? One theory
• Recognition-by-components
• - We detect components of object and then compare
  to our database
• - Incomplete theory!

10
Perceptual Organization-Depth Perception

• Depth Perception
• ability to see objects in three dimensions
• allows us to judge distance
• Binocular cues
• 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

11
Perceptual Organization-Depth Perception
Visual Cliff
12
Perceptual Organization-Depth Perception
relative size smaller image is more distant
Relative Size
13
Perceptual Organization-Depth Perception
You can tell one is closer to you then the
other closer object blocks distant object
14
Perceptual Organization-Depth Perception
Perspective Techniques
15
Perceptual Organization-Depth Perception

• Monocular Cues
• relative size
• interposition
• relative clarity
• hazy object seen as more distant
• texture coarse --gt close fine --gt distant

16
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

17
Perceptual Organization-Motion Perception

• Motion detectors in neural pathways
• Changing images across the retina when eyes not
  moving and
• Stable images on retina when eyes moving
• this doesnt refer to saccades, rather the
  side-to-side eyeball sweep

18
Perceptual Constancy

• Perceptual Constancy
• unchanging despite changes in retinal image
• brightness
• shape
• size
• color

19
Sensory Restriction-Blakemore Cooper, 1970

• Kittens raised without exposure to horizontal
  lines later had difficulty perceiving horizontal
  bars.

20
Perceptual Interpretation

• Perceptual Adaptation
• (vision) ability to adjust to an artificially
  displaced visual field
• prism glasses
• Perceptual Set
• a mental predisposition to perceive one thing and
  not another

21
Perceptual SetSchemas

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

22
Perceptual Set- Schemas
Flying Saucers or Clouds?
23
Perception without Sensation?

• Extrasensory Perception
• controversial claim that perception can occur
  apart from sensory input
• telepathy
• clairvoyance
• precognition
• Parapsychology
• the study of paranormal phenomena
• ESP
• psychokinesis