Can We Trust Perception? (Pt.1)
P S YC H 1101 : DAY 13 P ROF. DAVID P IZ AR RO CO R NE L L P S YC H . NE T
Sensation and perception give us an internal representation of the world
How Accurate And Objective Is It?
Perception Is Not Perfect • •
We are susceptible to a variety of visual illusions! What we see can vary depending on other visual cues present!
•
Visual context: shadows, surrounding lines, etc.
E BBING H AU S IL L U S IO N
Perception Is Not Perfect •
We know that we are susceptible to illusions, and that what we see can vary depending on other visual cues present!
•
•
Visual context: shadows, surrounding lines, etc.!
Also shaped by broader context--expectations about what you’re perceiving!
•
e.g., interpretation of ambiguous figures
The “Mcgurk Effect”: An Auditory Illusion
Are There “Top-Down” Effects On Perception? •
“Lower level” cognition: sensation, perception (basic identification and categorization)!
• •
“Higher level” cognition: beliefs, thoughts, desires, motivations ! Most processing of information is obviously of the “bottom-up” variety!
•
•
sensations ---> perceptions ---> judgments/beliefs/emotions!
Can our beliefs, thoughts, desires, emotional states actually change the way that we perceive the world?
Possibility 1: Basic Perception Is “Protected” Against Influence •
Basic perception (esp. visual) is “modular”!
•
“cognitively impenetrable” or “informationally encapsulated.”!
•
Sensory information is processed by low-level computations that give rise to perception. !
• •
This output feeds into our higher-level cognitive systems.! This is actually why many visual illusions continue to work despite our knowledge that they are giving us incorrect information.
Possibility 2: No! Even Basic Perception Is “Infused” With Our Desires, Beliefs, Thoughts • •
There is no such thing as “pure” perception!
•
These don’t just shape our interpretation of what we see, but what we actually see.
People actually perceive the exact same stimulus in a completely different manner, depending on their values, motivations, beliefs, cultural backgrounds, etc. !
!
What Is At Stake? Universality And Reliability
!
“I hate relativism. I hate relativism more than I hate anything else, excepting, maybe, fiberglass powerboats... surely, surely, no one but a relativist would drive a fiberglass powerboat.”!
J E R RY F OD OR , AUTH OR OF “ M O D U L AR I T Y AN D M I N D ”
What Is The Answer? Which Possibility Is The Right One?
Language And The Perception Of Color •
The Sapir-Worf hypothesis (linguistic relativity) is that the language we speak constrains our perception and cognition.!
•
Specific prediction: !
•
our basic perception of color depends on the categories we have for carving up the visible spectrum. !
•
e.g., not all languages have a blue/green linguistic distinction
How Two Languages “Carve” The Visible Spectrum
What Do We Know? •
Linguistic color categories shape a great deal of “color cognition”!
•
•
memory, learning, and discrimination!
But there appear to be clear basic universals in perception!
•
infants and individuals from cultures with only terms for “light” and “dark,” are able to tell the difference between “focal” colors (i.e., basic red, green, blue, yellow, etc.)
Resolving Ambiguity: Personality And Perception
Berg & Toch (1964): Seeing Violence •
Subjects:!
• • • •
• •
Inmates of the State Prison of Southern Michigan at Jackson.! 60 men were selected on the basis of their disciplinary record in the institution! MMPI! case history data!
“Impulsive” Group vs. ! Neurotic (“Control”) Group!
• •
An absence of disciplinary violations! case histories of anxiety attacks, psycho-somatic diseases, gross introversion, etc.
Binocular Rivalry Slides
•
(1) The "Lover-Groom" Slide: a man embracing a woman.!
•
IMPULSIVE: the backdrop consists of a bed.!
•
SOCIALIZED: the woman wears a bridal dress; man a top hat; backdrop an altar.!
•
(2) The "Striptease-Show" Slide: persons watching a female stage performer.!
•
SOCIALIZED: the performer is dressed!
•
IMPULSIVE: she is not.!
•
(3) The "Beer-Coffee" Slide: Both pictures feature a man drinking against a counter or stove.!
•
SOCIALIZED: he holds a coffee cup;!
•
IMPULSIVE: he drinks out of a beer mug.!
•
(4) The "Glutton-Diner" Slide: A man is depicted eating, with the difference being the manner in which he eats.!
•
IMPULSIVE: consists of a meal "a la Henry VIII," consisting of an entire chicken devoured "in the rough.”!
•
SOCIALIZED: a conventional knife-and-fork meal.!
•
(5) The "Rapist-Dancer" Slide:!
•
IMPULSIVE: features a couple dancing, while in the other picture, !
•
SOCIALIZED: the man is violently struggling with his partner, whose clothes he is tearing off.
Results Experimental group Control group Number of “naughty” images they saw