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What are the differences
between the two?
2. Which is more susceptible to cultural or contextual influence, sensation or perception?
Why?
3. How are individuals able to tell when their perceptions have been influenced by cultural or
contextual factors? Is there a way to eliminate these biases from perception? These factors
probably always influence perception, but knowing that they do gives the perceiver
knowledge that may help minimize its negative impact.
4. Are the differences in perception among humans likely to be larger or smaller than the
differences in perception among ants? Assuming that human cultures are more diverse
than ant cultures, the differences in perception should be greater for humans. Larger
cultural differences would produce larger variations in perception.
5. You might ask students if they believe that advertisers put hidden messages in their
advertisements. Follow up by asking if they believe those messages work. You can use this
to lead into a discussion of subliminal perception and its supposed effects. Stories of
subliminal visual messages go back to claims of their inclusion in movies in the 1950s.
Subliminal verbal messages have been discussed at least since the controversy about the
Beatles supposedly putting hidden messages in their albums in the late 1960s. However,
the evidence that these messages have any real effect on behavior is currently lacking.
Stories about subliminal messages continue to regularly appear in the media, and it is
surprising how many people believe that the messages work.
6. As an example of motion parallax, you might ask students if they have ever traveled with
young children on a clear night with the moon near the horizon to one side of the road on
which you are traveling. Whereas the trees, houses, and hills seem to move steadily by, the
moon appears to be traveling along with you. Many times young children will exclaim that
the “moon is following us.” There have even been UFO reports generated by this
phenomenon on cloudy nights when adults have mistaken the moonlight for a flying object
darting in and out of the clouds and following them along the horizon.
7. To illustrate the fact that the brain interprets messages from the skin’s hot and cold
receptors relative to previous and surrounding stimuli, set up three small basins in the
front of the class. Fill one with hot water (but not so hot that it will burn someone’s skin),
one with cold water, and one with luke-warm water. Have students put one hand in the
basin of hot water and the other hand in the basin of cold water. Then have them place
both hands in the basin of warm water. They should notice that in the warm water, one
hand (the one that was in the cold water) will sense it as being hot, while the other hand
(the one that was in the hot water) will sense it as being cold.
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SUPPLEMENTAL LECTURE MATERIAL
Eyes and Camera Lens
For many years, it was believed that the eye worked like a camera, and there are some similarities.
For instance, both the pupil of the eye and the aperture of a camera contract and expand in
response to a respective increase or decrease in the amount of light entering the apparatus.
Nevertheless, in comparing the human eye to a camera, some of the differences between these two
are striking.
Perhaps the strangest difference between the human eye and a camera lens is the position of the
retina and the analogous film. For a camera to be like the human eye, we would have to load our
film into the camera backward. That is, the photoreceptors actually pick the light up off the back of
the surface of the eyeball. A camera must be held relatively still to capture a clear image, but when
the eyeball is held still, the picture disappears. Both the camera and the eye have a lens that focuses
an image on a surface, but the two have different methods of focusing. The lens in a camera moves
closer to or farther from the film in order to focus the image on the film; the lens in the eye changes
shape to focus the image on the retina. This process is called accommodation.
An upside-down mirror image is focused on both the film and the retina; however, the film and the
retina differ in that the film records the image exactly as it is projected. The photoreceptors in the
retina receive information from visual stimuli; those stimuli are analyzed and reconstructed as they
move through the visual system from the retina to the cortex. What we perceive is a picture that is
not identical to the item we are looking at. Photographs in which people have their feet extended
closer to the camera in front of them are comical because we take relative distances into account and
perceive the feet as being a constant size.
Everyday Examples of Gestalt Principles
Bring in everyday examples of the Gestalt principles of perception from magazines or artworks.
Transparencies of the examples can be made on a copy machine, and then used on overhead
projectors. For example, in Escher’s Mosaic II, one sees a group of black creatures on either a white
background or a group of white creatures on a black background. H. A. Broos explains how
Escher’s prints have been used in geology, chemistry, and psychology in The World of M. C. Escher.
This book also contains a chronological survey of Escher’s work and includes a number of useful
examples, such as illustrations of figure and ground in the woodcuts “Sky and Water I” and “Sky
and Water II.”
A Brief History of Gestalt Psychology
The Gestalt movement in psychology was established in Germany in the early 1900s, and was
based on the Gestaltist’s opposition to the structuralist movement. In essence, the structuralist
movement proposed that all phenomena could be broken down into their most primitive perceptual
elements. The Gestaltists took exception to that philosophy, arguing that psychological phenomena
could be understood only if they were studied as organized, structured “wholes,” thus maintaining
the “unitary essence” of the phenomena.
The Gestaltists extended this philosophy to learning, in viewing it as a restructuring or
reorganization of an entire situation, and a process that often included insight as a critical aspect of
that process. Brain physiology was perceived in the same context, in that Gestaltists saw the brain
as isomorphic, as having a relationship between the excitatory fields in the cortex and the
conscious experience of the individual.
Gestalt psychology, as a distinct discipline, is rarely found today, although many of the insights it
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fostered and discoveries have been incorporated into contemporary psychology.
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PSYCHOLOGY AND LIFE
BIOGRAPHICAL PROFILES
Eleanor Gibson (b. 1910)
Eleanor Gibson graduated from Smith College in 1931 and obtained her Ph.D. at Yale in 1938.
Gibson was instrumental in studying perceptual development in children, inventing the visual cliff
as a means of studying depth perception. Her interests in experimental psychology were influenced
by her husband, J. J. Gibson, whose research and theory on perception have challenged the more
popular Gestalt and information-processing accounts that hold that a stimulus undergoes
considerable interpretation via cognitive processes. Gibson received the American Psychological
Association Distinguished Scientific Contribution Award for her research on depth perception.
William Rutherford (1839–1899)
William Rutherford was born in Ancrum, Scotland, and received his M.D. at the University of
Edinburgh. His first academic appointment was at King’s College, London, but he eventually
returned to Edinburgh as a professor of physiology in 1878. He is well known for his research on
the influence of the vagus nerve on circulation and on drug effects on the secretion of bile, as well as
for his physiological textbook published in 1880. He is best known in psychology for his
“Telephone Theory” of pitch perception, which argues that the Organ of Corti vibrates in a manner
that duplicates the frequency of vibrations of the tympanic membrane and ossicles. This frequency
theory of pitch perception, a major competitor to Helmholtz’s place theory, seems to account well
for our perception of low- and middle-frequency sounds.
Max Wertheimer (1880–1943)
Wertheimer was born in Prague, Austria-Hungary. His father directed a private business college
and his mother was an accomplished amateur violinist. Wertheimer studied law, philosophy, and
psychology at Charles University in Prague. He later studied philosophy and psychology at the
University of Berlin under Carl Stumpf, then moved to the University of Surzburg in 1904, obtaining
his Ph.D. under Oswald Kulpe. Wertheimer first discovered the phenomenon of apparent motion
during a train trip, and later conducted studies on the phi illusion at Frankfurt, where Wolfgang
K.hler and Kurt Koffka, his cofounders of the Gestalt school of psychology, participated as his
research participants. In 1933, Wertheimer fled Germany due to Hitler’s rise to power, coming to the
United States. He taught at the New School for Social Research in New York City until his death in
1943.
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TIMELINE
Yea Event
r
1815 Napoleon was defeated at the battle of Waterloo and banished to St. Helena.
1838 Johannes Müller formulated his doctrine of specific nerve energies, which states
that sensory experience depends not on the stimulus, but on the part of the
nervous system that is activated.
1846 Ernst Weber postulated that the difference threshold is a constant proportion of
the initial stimulus intensity, a notion later formalized as Weber’s Law.
1857 Based on the earlier work of Thomas Young, Hermann von Helmholtz proposed
that color vision is due to three different types of color receptors (cones), each of
which is sensitive to a specific range of wavelengths of light.
1860 Gustav Fechner published Elemente der Psychophysik, marking the founding of
psychophysics, the study of the relationship between subjective experience and
physical stimulation.
18611865
The American Civil War was fought.
1881 Pasteur and Koch discovered the germ theory of disease.
1917 The Bolshevik Revolution was fought in Russia.
1938 H. Keffer Hartline discovered that optic nerve fibers respond to stimulation from
different receptive fields.
1948 Israel became an independent nation.
1953 The genetic code was broken.
1954 Tanner and Swets proposed the application of signal detection theory to the study
of thresholds.
1957 S. S. Stevens demonstrated that changes in one’s subjective impression of stimulus
magnitude are a power function of the actual stimulus magnitude.
1957 Leo Hurvich and Dorothea Jameson, building on the earlier work of Ewald
Hering, postulated the theory that color vision is based on opposing neural
processes, the opponent-process theory of color vision.
1959 David Hubel and Torsten Wiesel discovered that cells in the visual cortex of cats
(and, in 1968, of monkeys) respond differentially to form and movement.
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PSYCHOLOGY AND LIFE
SUGGESTIONS FOR FURTHER READING
Goldstone, R. L. (1995). Effects of Categorization on Color Perception. Psychological Science, 6(5), 298—
304. Suggests that category learning influences the perceptual discrimination of color attributes.
Provides empirical evidence that cognition influences perception by examining the influence of
learned categorization on color perception.
Kosslyn, S. M. (1995). Visual Cognition: An Invitation to Cognitive Science, Vol. 2 (2nd ed.). Cambridge:
MIT Press. Explores the mental aspects of visual processing. Discusses the important research,
discoveries, and insights in various areas of research on visual cognition and attempts to
integrate work from related fields.
Kosslyn, S. M., & Koenig, O. (1992). Wet Mind: The New Cognitive Neuroscience. An excellent volume
that introduces the field of cognitive neuroscience to the uninitiated. This volume covers a range
of cognitive and neurological issues, to include sensation and perception. Well written and easy
for even the lay person to understand.
Link, S. (1994). Rediscovering the Past: Gustav Fechner and Signal Detection Theory. Psychological Science,
5(6), 335–340. Suggests that the origins of experimental psychology are found in the theoretical
works of Gustav Fechner and that Fechner is not given the credit that he is due for his
contributions. Argues that his works spawned many new ideas and theories, including the
response bias found in signal detection theory.
Matlin, M. W., & Foley, H. J. (1992). Sensation and Perception (3rd edition). Boston: Allyn and Bacon.
A well-written introduction to the fields of sensation and perception.
Meyering, T. (1989). Historical Roots of Cognitive Science: The Rise of a Cognitive Theory of Perception
from Antiquity to the Nineteenth Century. Dordrecht: Kluwer Academic Publishers. Begins with the
Aristotelian theory of perception and then works its way to nineteenth century theories of
perception. A very thorough review of the history of perceptual theories.
Sabourin, M., Craik, F., & Robert, M. (1998). Advances in Psychological Science, Vol. 2: Biological and
Cognitive Aspects. Hove: Psychology Press/Eribaum (UK) Taylor & Francis. Covers a wide range
of topics in human and animal experimental psychobiology. Provides an excellent review of
current research in many areas of psychology including perception.
Sekuler, R. (1995). Motion Perception as a Partnership: Exogenous and Endogenous Contributions. Current
Directions in Psychological Science, 4(2), 43—47. Describes the process of motion detection as a
result of the interaction of exogenous and endogenous influences.
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DISCOVERING PSYCHOLOGY
PROGRAM 3: THE BEHAVING BRAIN
Overview
The structure and composition of the brain: how neurons function, how information is collected and
transmitted, and how chemical reactions determine every thought, feeling, and action.
Key Issues
The biology of the brain, how the brain processes information, the electroencephalogram (EEG),
neurometric evaluation, the effects of drugs on the functions of the brain, the brain’s own manufactured
chemicals, and neurotransplantation.
Demonstrations
Multiple brain wave recording to reveal various types of brain malfunction.
Effects of chemicals on learning and memory in rats.
New Interviews
John Gabrieli illustrates how the brain stores and retrieves information.
PROGRAM 7: SENSATION AND PERCEPTION
Overview
Explores how we make contact with the world outside our brain and body. See how biological,
cognitive, social, and environmental influences shape our personal sense of reality, and gain
an understanding of how psychologists use perceptual errors to study how the constructive
process of perception works.
Key Issues
Visual illusions, the biology of perception, the visual pathway, how the brain processes
information during perception, sensory feedback in visual perception, and perceptual
constancy.
Demonstrations
Sensory feedback in visual perception. A Stanford student demonstrates the problems football
quarterbacks face in the adjustment to special kinesthetic cues with distortion goggles that
displace feedback from the perceived visual field.
Perceptual constancy. Philip Zimbardo demonstrates visual misperception in the Ames
distorted room in the Exploratorium in San Francisco.
Interviews
Nobel Prize winner David Hubel explains the mapping of the reaction of receptor cells along
the visual pathway of primates. Hubel’s award-winning experiment of the response of neurons
to electrical activity in the visual cortex of a cat illustrates his point.
Misha Pavel uses computer graphics to demonstrate how the visual system of the brain breaks
down and recombines visual stimulation into recognizable, coherent images.
FILMS AND VIDEOS
A Touch of Sensibility (1981). BBC, 50 minutes
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PSYCHOLOGY AND LIFE
This NOVA presentation discusses the importance of touch and the effects of touch deprivation.
This film examines the importance of touch for development at various age levels. Many interesting
areas of research are cited.
Brain Power (1983). IU (LCA), 11 minutes
Discusses three principles of perception that affect how a person receives information: recognition,
interpretation, and expectation. Throughout the film, visual cues, puzzles, and optical illusions
remind the viewer that one’s perceptions can be easily fooled. A brief, clever film that stimulates
students’ interest in sensation and perception.
Human Perception: A Collection of Demonstrations and Effects (1986). Hanover, N.H.:
Dartmouth College, Office of Instructional Services and Educational Research. Contains real-time
segments, single frames, picture and chapter stops.
The Mind: Pain and Healing (1988). HARR, 24 minutes
Reviews the influence of the mind on people’s ability to control pain and on their ability to promote
physical healing. An excellent film. Traces the progress of a woman through a three-week clinic
program to reduce chronic, long-term pain. The changes in her movement and affect are dramatic.
Demonstrates the placebo effect, and shows how cues, such as a doctor’s white coat, can trigger the
release of endorphins to reduce pain. In the final segment, a cancer patient discusses how the
interaction of cognitive therapy with physical therapy has increased her life expectancy and her life
quality.
The Senses: Eyes and Ears (1985). FFHS, 26 minutes
Visual and auditory distance receptors are discussed. Demonstrations of how each processes
information are also shown.
The Senses: Skin Deep (1985). FFHS, 26 minutes
The sense receptors that depend on immediate contact with the world—taste buds, olfactory cells,
and touch sensors—are examined.
CASE STUDY LECTURE LAUNCHER
One night in 1965, a United Airlines Boeing 727 started a steady descent to Chicago’s O’Hare
Airport from an altitude of 22,000 feet. Nineteen miles off the shore of Lake Michigan, the plane
plunged into the lake. One month later, also at night, an American Airlines Boeing 727, preparing
to land at Kentucky’s Boone County Airport, followed the thread of the Ohio River toward the
runway which began at the river’s steep south bank. The plane failed to make the runway, and
crashed into the bank, 12 feet below the runway. One night in early 1966, an Al Nippon Airlines
Boeing 727 headed toward Tokyo Bay. The pilot could see the lights of Tokyo and Yokohama
clearly. He requested and received permission to approach using visual cues rather than relying
exclusively on the instruments of the plane. The pilot had not even let down the wheels or extended
the flaps when, six and a half miles from the runway, the plane dove into Tokyo Bay at 240 knots.
Preliminary analyses of these and other similar cases showed that all of the accidents occurred at
night, under clear weather conditions, with the planes flying over a dark area of water or land. In
every case, irregular patterns of light (as opposed to grids of neatly intersecting lines of streetlights)
in the distance had been visible to the pilots.
In a way, the new Boeing 727 design was partly responsible for the accidents, because it was so
well engineered. In earlier, less stable models, feedback from vibrations, sounds and kinesthetic
sensations would have warned pilots that they were descending too rapidly. However, it was more
than an improved design that had caused the accidents.
Using a flight simulator, engineering psychologist Conrad Kraft found that an error in the pilot’s
visual perception was responsible for each of the accidents. Pilots making a visually guided
approach over a dark terrain relied on the relatively constant visual angle between their planes and
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the distant light patterns in determining their altitudes. If they were approaching flat terrain, their
altitude estimates were generally correct, but if the terrain sloped upward, with the farthest lights
higher than the closer ones, even the most experienced pilots descended to dangerously low
altitudes. With no visual information from the “black hole” below them, the pilots overestimated
their distance from the ground and inappropriately adjusted their descent angles.
Why didn’t the pilots also use their altimeters, which indicated altitude accurately?