Perception Lecture Notes
James R. Pomerantz (pomeran@rice.edu)
Rice University, 2002

 

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Perception is an important area of inquiry because:

Perception is the key mediator between stimulus and response
Perception is the source of most knowledge that humans acquire

Perception is interdisciplinary, embracing art (including music), philosophy (epistemology, logic), mathematics, engineering, biology, medicine, psychology, and other fields.

Perception is largely an unconscious process, and thus it complexity tends to be underestimated

Perception is transparent to the perceiver – we notice it only when it misfires.  Examples: the blind spot; neglect.

Researchers failed to appreciate the magnitude of the problem of perception until we tried to simulate the process (Marvin Minsky, MIT, artificial intelligence)

Perception can seem impossible (as with the flight of bumblebees), but fortunately, the stimulus field is redundant, resulting in  over-determination.

Our subjective notions of how perception works are naïve.  Example: Superman’s x-ray vision

The key function of perception, including all its components is survival.  The key information source comes from the constancies, invariants that tell you about the world

Perception involves a complex chains of events, both in vision and in the other senses such as audition.

Eight facts about perception.  Perception:  

  1. Is limited:  Frequency spectrum, Infrared Scene, Mite, Powers of Ten, Edgerton Bullet.

  2. Is selective: cocktail party phenomenon

  3. Requires memory: Recognition

  4. Is not entirely veridical (trustworthy): Hermann Grid, Spiral Illusion, Simultaneous Contrast, optical, moon illusion (below)

  5. Takes time: flicker, Metacontrast

  6. Corresponds more to the distal than to the proximal stimulus: Shepard Boxtops , Adelson Shadow Effect

  7. Involves the active organization of sensory information: Hexagram of Spots,R. C. James Photograph , Necker Cube,   Subjective Necker Cube

  8. Focuses on change, not on steady-state information: disappearance of stabilized images, adaptation, McCollough Effect

Study a black-box system by:

  1. Peeking inside (PET scans, MRI)

  2. Measuring the system's response time (human RT studies)

  3. Looking for errors the system makes (illusions)

Illusions (for more, see Illusionworks and see the PBS site www.pbs.org/wnet/brain/illusions/index.html ):

  1. Optical - ones that originate in the world, not in us (grass is greener; pencil in water)

  2. Perceptual - early (e.g., floaters, afterimages, rubber pencil; aftereffects - short and long term)

  3. Perceptual - late (Muller-Lyer, rainbow, metamers in color, barberpole motion)

Illusions in the 'real world': seven moon illusions

  1. Size at horizon

  2. Moon through moving clouds

  3. Moon through side car window

  4. Moon completion

  5. Man in the moon

  6. Craters - depth illusion

  7. Disk (vs. globe) illusion
       Mars: Lowell's 1900-1911 claim: NYT's story, explanation

Reference on McCollough effect (red and green vertical and horizontal stripes)
McCollough, Celeste (1965). Color adaptation of edge-detectors in the human visual system. Science, 149, 9 1115­1116.

Infrared Scene

Dust Mite

Edgerton Bullet

 

Hermann Grid

Spiral Illusion

Simultaneous Contrast

 

Shepard Boxtops Demo

Adelson Shadow Effect

 

Hexagram of Spot Circles

R. C. James Photograph

Necker Cube

Subjective Necker Cube   (Bradley, Dumais, and Petry, 1976)

 

Minsky - Papert spirals

Visual Cortex

Brain Pathways

Retina Layers

Stroop Effect

 

Motion aftereffect with rotating spirals: see http://www.discover.com/dec_99/brainworks.html

 

 

MRI of human head, left saggital view

 

Shepard Box Tops Illusion: the two textured areas are identical in shape.
From Shepard, R.N., Psychophysical Complementarity.
In M. Kubovy and J. R. Pomerantz, Perceptual Organization.  Erlbaum, 1981.