PSYC 3220 Exam 1 Pagano Sensation and Perception Clemson University

The means by which we gain knowledge about what's in the world around us (how information gets from the world into our head)

sensation and perception

The fundamental purpose of perception

prospective control

What did Aristotle say in 350BC?

Perception involves 3 tings: animal, medium, object

What medium did ancient philosophers believe in?

spiritual energy

Fundamental problem of perception

How information crosses the gap between the object and the animal -- cannot involve action at a distance

Action at a distance

the concept of two objects interacting without touching

What answer did greek thinkers propose to the problem of perception?

we get copies of things in our heads via an active mental process

Principle of representation

in order to perceive something, you must get a copy of it into your head

Intromission

our eyes capture a copy of an object, of which there are infinite shedding off of the object

Emanation

spiritual energy hits the object and returns to our head with a copy

What theory did Alkindi propose in 850AD?

Pointillistic theory of emanation

Pointillistic theory of emanation

emanations are composed of "pencils" or "rays"

What new perspective did Alhazan introduce in 1000AD?

The idea of the eye as an optical instrument; had an intromission theory similar to the pointillistic emanation theory

Essential elements of most modern theories of visual perception

principle of representation, structured light, pointillism, mental entity

What parts of the eye did Kepler discuss in 1600AD?

the retina on which images are formed, and the lens which focuses light

Destructive mapping (Kepler)

the images on the retina are 2D, losing 3D information

What did Molyneux assert in 1692AD?

Distance is a line with its end towards us, which must be a point; thus, distance is invisible

The problem with (visual) perception

proximal stimulus is inverted, distorted, 2D, changing...

Mental entity

adds order to the effects of the senses

Ontology

theories about what exists

Materialism (a monism)

the mind and body are made up of one material thing

What ontology did Plato introduce in 400BC?

mind-matter dualism, the concept the body is made up of matter-based things and the mind is made up of spiritual things

Epistemology

theories about how things can be known

nativism (an epistemology)

knowledge is inherited

empiricism (an epistemology)

knowledge is learned through observation

rationalism (an epistemology)

knowledge comes through reason

What take on mind-body dualism did Rene Descartes hold in 1625AD?

the mind is a ghost in machinery; the soul resides in the center of the head. the world can only be known through reasoning what causes given sensations (indirect perception)

What take on perception did Johannes Muller hold in 1826AD?

perception is a state of the nerves (you can experience seeing light by stimulating those nerves); nerve impulses come between awareness and the world

Muller's theory of specific nerve energies

quality arising from a sensation depends on what particular nerves are stimulated

empiricism

mental contributions to perception are learned

John Locke 1690AD

born with no ideas; gained through experience

Locke's primary qualities

exist in the world

Locke's secondary qualities

imposed on the world my the mental entity

George Berkeley 1710AD

perceiver can't tell the difference between primary/secondary qualities; there is no guarantee. distance is suggested by cues, but not sensed. cues acquire meaning via association and are used to construct copies

Irvin Rock

brain is capable of constructing 3D scene from 2D image

Light varies in what 2 things?

amplitude, wavelength

Greater amplitude =

brighter

Longer wavelength =

redder

Light is structured by surfaces according to what 3 factors?

amount absorbed, wavelengths absorbed, and degree of scatter

Ambient optic array

structured arrangement of light with respect to a point of observation

4 reasons light can serve as a visual medium

Travels in straight lines, selectively absorbed/reflected, can be refracted (focused), instantaneous

depth of field

range of distances over which the image is focused

emmetropia

perfect vision

myopia (nearsighted)

eyeball too long, rays focus in front of retina

hyperopia (farsighted)

eyeball too short, rays focus behind retina

astigmatism

cornea is football shaped

photoreceptors contain

photopigments (RGB)

Retinal layers

receptors, bipolar, ganglion

adaptation

change in sensitivity over time; most often a decrease in sensitivity

dark adaptation is a special case

it is an increase in sensitivity to light

Newton's color experiments 1670

prism separates light into primary colors; colors of light can be mixed; color circle

additive color mixing

light

subtractive color mixing

pigment

principle of univariance

single receptor only conveys how much light it absorbed

metamers

pair of stimuli perceived as identical

Newton's revisions to color circle

purple as "nonspectral"; more shades of green than anything else

purkinje shift

during the day, eye is most sensitive to yellow; during night, eye is most sensitive to green