Psychology 329, Sensation and Perception

Dr. Bedford

Course Information

Sensation and Perception involves taking information from the world and transferring it to the mind. This can only be done through the 5 senses, vision, hearing, touch, smell and taste - the 5 gateways or portals between the external world and internal mental life.

"It fits in with a French idea of what life is about - the enjoyment of ones senses..." Theodore Zeldin, British sociologist



Required: Indv 101 (or Intro Psych), working knowledge of simple algebra, and some geometry, and trig.

Strongly recommended: The "Structure of Mind and Behavior" section of Indv 101(or Intro Psych), Experimental Methods with lab, and a minimum of 1 course from the Recommended list following.

Recommended: Cognitive Psychology, Cognitive Development, a basic Biology course, Statistics, Mechanisms of Learning, Language Acquisition

The more of the prerequisites you have, the more you will enjoy this class and the more you will be able to learn from it.


There are three themes which will run through the different topics of the course.

1) Evolution: How we perceive the world cannot be understood without asking the WHY question. e.g.Why do we have color vision? Why do we see at all? The answer to such why questions involves evolutionary considerations. Our perceptual abilities evolved through natural selection because those abilities led to greater survival advantage. (Note: knowing the ideas of Darwin and the theory of evolution by natural selection will help you do well in this course, but it is not an absolute prerequisite; we will teach you the evolution you need to know).

2) Learning: Perceptual systems that allow you to perceive the world are actually constantly changing,. They need to do this to remain accurate - otherwise, like an old clock that's never been reset to the correct time, error would accumulate and get increasingly inaccurate. One can think of learning or plasticity as "evolution", in a way, except with changes to perceptual systems over the course of the lifetime of an individual, rather than the lifetime of the species! (Note: knowing various mechanisms of learning, e.g. Pavlovian conditioning and/or language acquisition, and/or computer learning etc. will be helpful to allow you to compare how learning is involved in perception, but it is not an absolute prerequisite).

Mathematics: Sensation and Perception is one of the "hard science" areas of psychology. Numerous laws have been discovered that are best captured through mathematics. Note: For this course you need to have some knowledge and ability in mathematics including algebra, geometry, some trigonometry - basically just high school mathematics. Most importantly, you need to not be "scared" of it or find it so aversive you can't bring yourself to reason about it.


There will be both in-class exams and take-home exams for a total of 6 "midterms" and 1 final exam. Exam dates and whether an exam will be held in class or taken home will be announced ahead of time - usually one week before the exam. All exams are equally weighted for your final grade (100 points each).

There may also be homework assignments for some of the readings.

A final percentage score of 90% and above is an A; 80-89% is a B; 65-79% is a C; 51-64% is a D; below 51% is an F.

There will also be opportunities to raise your grade - special projects, experiments, and class discussions.


It should be clear, but in case it's not: Do not copy someone else's take home exam, or in-class exam. If exams match, they will both be given failing grade. If you want to brainstorm as a team, come talk to me first for approval.

Any information you get from the web must, like all sources, be cited and acknowledged in your work. Any word for word quotes (or a few words changed) must appear in quotation marks, or it is plagiarism. Changing a few words is also plagiarism. Ask if you are unsure.

Class format

Lecture, with as much time for discussion (both 1 big discussion and small discussion groups) and possible short presentations as a big class allows. Readings are difficult, and discussions usually help.


The readings will be actual journal articles and book chapters taken from highly regarded journals such as Perception, Perception and Psychophysics, Journal of Experimental Psychology: Human Perception and Performance, Psychological Review, Cognition, Cahiers de Psychologie Cognitives, Trends in Cognitive Sciences and well-regarded professional books. Some articles will be available at a copy center, others available on the web, and others we will distribute in class.

The articles can be difficult to get though and may require some time before you learn which parts need to be read carefully and which can be skimmed - it's a skill that anyone who reads journal articles develops. Discussion can be used to clarify readings if desired.


Besides after class, you can get hold of us by email ( and

Teaching Assistant.

The TA for this course is Dusana Rybarova. She will be attending classes, grading most of the assignments, participating in and leading some of the discussions, and meeting with you during office hours if desired.


There's a "sister" course next semester, Psych 396H, Honors Proseminar, which I will be teaching. Some of the course will include lab experiments you can do on some of the material you'll be learning about in this course. Psych 396H is an honors course - if you are not an honors student but receive an A in this course you can take it. Others who are interested feel free to discuss it with me.

About your instructors:

Dr. Bedford is an Associate Professor of Psychology and Program in Cognitive Science. She received her Ph.D. in 1988 from the University of Pennsylvania in Philadelphia, Pa. Her focus in Psychology is in Perception, Learning and Cognition with research specialty on the effects of experience on perception. Non-academic interests include genealogy, skateboarding (ok, a while ago...), and Brooklyn, New York

Dusana Rybarova is

Course Outline

(topics and order of topics subject to change)

  1. Perceptual Expertise.
  2. Can you be an expert at perceiving with practice?

    Perceiving cat faces

    Perceiving human faces of another race

    Faces in photographic line-ups

    Bird watching, wine tasting, xray technicians, orientation

    (work of E. Gibson, O'toole, Karni and Sagi, others)

  3. Camouflage

Is it a coincidence that animals look like their surroundings?

Evolution of perceptual abilities to detect objects

Co-evolution of physical and behavioral traits to avoid detection!

(work of Gestaltist Wertheimer and others, Kubovy, Palmer)

III Some basic principles in vision

What is light?

Light and the pathway from light to the eye

Why doesn't the world look chaotic every time you move your head?

Size constancy, shape constancy, position constancy, motion constancy

Why should the world look flat?

The retina is flat

Why doesn't the world look flat?

How we perceive depth

How can something as complex as an eye ever evolve?

Gradual evolution of the eye

(Dawkins, Gregory)

How does the eye work?

Near sightedness

Far sightedness

Normal vision

IV Space and Time

Changing the perception of Space

Adaptation to Prism distorted vision (Harris, Welch, Wallach)

Why should this happen? (Bedford)

Changing the perception of Time

Can the perception of time be changed? Reversed? Little is actually known about this area compared to other types of perception

Time Adaptation (Cunningham)

Perception of Space and Time - are they analogous?

Does physics have anything useful to say?

Theory of indispensable attributes (Kubovy)

V. Perceptual Expertise revisited. Why does it happen? Is it similar to perceptual adaptation? Other types of "perceptual learning", e.g. McCollough Effect.

Perceptual Learning Theory (Bedford)

Any general learning models useful? Rescorla-Wagner model (Rescorla)

How do we form perceptual categories? (Goldstone?, Medin?)

VI Cross-Modal perception

Does each of the different senses forms its own representation of the world? If so, how are they put together to yield a single coherent image of the world? What if the information conflicts? Many of the above examples involve situations where different sense modalities conflict - are there any general conclusions that can be drawn? Also consider other examples of cross-modal conflicts and cooperation:

Ventriloquism (at the movies and in vaudeville acts), vision vs. audition about space

Dancing Christmas light effect, vision vs. audition about time

Other capture effects (e.g. vision vs. touch - Rock and Harris)

McGurk Effect, vision vs. audition about language

Synesthesia (confusion among the senses - hearing colors etc.)

Integrating information from different modalities

Fuzzy logic model (Massaro)

Applied to: language (phonemes)

Depth perception - different cues to depth

VII. Evolution of general perceptual principles

Did we evolve perceptual universals that are as general as the laws of physics (Shepard)?

Three dimensions of color perception, 3 dimensions of space, generalization (Shepard)

Numerical/Object Identity (Bedford)

VIII. Two modes of perceiving

Affordances - enable us to act on the world (J. Gibson)

Affectances - enable us to go beyond what's in the world, symbol use, aesthetic judgements, uniquely human (Ittelson)

Example of affordances:

How does a dog catch a Frisbee (McBeath)?

Example of Affectances

Theories of aesthetics (maybe)

Dissociations between different perceptual systems:

A neurological dissociation between perceiving objects and grasping them (Goodale, Bridgeman)

What vs. where systems in perception (Mishkin)

IX Physical growth

From infancy until adulthood the physical body grows, yet perception must remain the same. What kinds of perceptual changes does growth require and how do we accomplish them?

The ears get further apart - how can we continue to localize sound accurately? (Held, Clifton)

The shoulders get further apart -how can we continue to point to objects accurately? (Bedford)

The eyes get further apart - how can we continue to perceive depth accurately?(Banks)

If there is time in the course: perception in infancy.

What do infants perceive?

Innate perception and knowledge about the world (Spelke, Carey, Wynn)

Perceptual and learning biases - symbolic language systems (Gomez, Gerken)

Brain Development (Marcus)

X. Consciousness, perception, and disorders

What are we aware of when we perceive?

Why are we aware of anything?

Do animals have the same consciousness as we do?

The classic Introspectionists

Anomalies of consciousness and perception:

Blindsight - Neurological disorder where people who behave as if they can see but insist they cannot

Subliminal perception- Stimuli people report they cannot see - yet they influence you. e.g. masked priming.

Other neurological perceptual disorders; e.g.,



The man who mistook his wife for a hat (Sachs)

Do they make sense for a general theory of perception?


(Some other topics, depending on time and interests: Psychophysics, signal detection theory, smell and taste in humans and dogs, what motion sickness has to do with perception, navigation, perception and social psychology/personality theory.)