Psychology: Themes and Variations - Chapter 4

Sensation

stimulation of sense organs

Perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Light

a form of electromagnetic radiation that travels as a wave, moving at the speed of light

Amplitude

Height of a wave

Wavelength

the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission

Perception of the brightness of color is affected mainly by

amplitude of the wave

Perception of color depends on....

the wavelengths of light that it reflects into the eye

Purity

how varied the mix of light is

Saturation

intensity of color

As whiteness declines

saturation increases

ultraviolet radiation

Electromagnetic waves with wavelengths that are shorter than visible light but longer than X-rays.

shorter wavelengths than humans can see

Insects can see these

Infrared spectrum

longer wavelengths (seen by fish and reptiles)

Cornea

The clear tissue that covers the front of the eye

Lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

Accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

Nearsightedness

a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina

Farsightedness

distant objects are seen clearly but close objects appear blurry

Pupil

the adjustable opening in the center of the eye through which light enters

Retina

The neural tissue lining the inside back surface of the eye; it absorbs light, processes images, and sends visual information to the brain.

Envoy of the eye

the retina

Cataract

a lens that is clouded

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Optic disk

A hole in the retina where the optic nerve fibers exit the eye.

The blind spot of the eye is

where the optic nerve leaves the eye (AKA the optic disk)

Cones

Specialized visual receptors that play a key role in daylight vision and color vision.

Fovea

A tiny spot in the center of the retina that contains only cones; visual acuity is greatest at this spot.

Rods

Specialized visual receptors that play a key role in night vision and peripheral vision.

100 times more sensitive than cones

Rods are __________________ this, allowing them to handle night vision

Periphery (outer areas) of the retina

Rods handle the lion's share of peripheral vision because they greatly outnumber cones here

Dark adaptation

The process in which the eyes become more sensitive to light in low illumination.

Light adaptation

the process whereby the eyes become less sensitive to light in high illumination

Receptive field

the region of the sensory surface that, when stimulated, causes a change in the firing rate of that neuron

100 million

number of rods and cones that information comes from

1 million axons

number of axons in the optic nere

The opposite

In receptive fields, light falling in the center has the _______________________ effect of light falling in the surrounding area

Optic chiasm

the point at which the optic nerves from the inside half of each eye cross over and then project to the opposite half of the brain

Main visual pathway

projects through the thalamus, where signals are processed and distributed to the occipital lobe

Thalamus

the brain's major relay station

Lateral geniculate nucleus (LGN)

A structure in the thalamus, part of the midbrain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.

Primary visual cortex

the region of the posterior occipital lobe whose primary input is from the visual system

Two pathways

After reaching the optic chiasm, the optic nerve fibers split along __________________________

The other visual pathway

Leaves the optic chiasm and branches off into an area in the midbrain (the superior colliculus) before traveling through the thalamus to the occipital lobe

superior colliculus

receives visual sensory input

Principal function of the second pathway

the coordination of visual input with other sensory input

Feature detectors

neurons that respond selectively to very specific features of more complex stimuli

what and where pathways

The Dorsal "where/how" Stream: Motion recognition

The Ventral "what" Stream: Object recognition

ventral stream

the what pathway

Function of the ventral stream

processes the details of what objects are out there (the perception of form and color)

dorsal stream

where pathway

Function of the dorsal stream

processes where the objects are located (the perception of motion and depth)

What

The temporal lobe is from this pathway

Monkeys and humans

species which have cells in the temporal lobe that are especially sensitive to pictures of faces

subtractive color mixing

Formation of colors by removing some wavelengths of light, leaving less light than was originally there.

Why paints yield subtractive mixing

Pigments absorb most wavelengths, selectively reflectinb back specific wavelengths that give rise to particular colors

Additive color mixing

Formation of colors by superimposing lights, putting more light in the mixture than exists in any one light by itself.

Trichromatic theory

theory of color vision that proposes three types of cones: red, blue, and green

color blindness

a variety of disorders marked by inability to distinguish some or all colors

Complementary colors

pairs of colors that produce gray tones when mixed together

Afterimage

A visual image that persists after a stimulus is removed; can occur when you stare at a strong color then look at a white background

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

Three types of cones

red, green, blue

reversible figure

A drawing that is compatible with two different interpretations that can shift back and forth.

the same visual input can result in

radically different perceptions

Perceptual set

a mental predisposition to perceive one thing and not another

Selection of sensory input

what people focus their attention on

Inattentional blindness

failing to see visible objects when our attention is directed elsewhere

Feature analysis

the process of detecting specific elements in visual input and assembling them into a more complex form

Bottom-up processing

analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

progresses from INDIVIDUAL ELEMENTS TO WHOLE

top-down processing

the use of preexisting knowledge to organize individual features into a unified whole

phi phenomenon

the illusion of movement created by presenting visual stimuli in rapid succession

Gestalt Psychology

a psychological approach that emphasizes that we often perceive the whole rather than the sum of the parts

monocular depth cues

stimuli that enable us to judge depth using only one eye

pictorial depth cues

clues about distance that can be given in a flat picture

linear perspective

A monocular cue for perceiving depth; the more parallel lines converge, the greater their perceived distance.

texture gradient

the tendency for textured surfaces to appear to become smaller and finer as distance from the viewer increases

interposition

if one object partially blocks our view of another, we perceive it as closer

relative size

larger image is closer, smaller image is more distant

height in plane

distant objects appear higher in a picture

light and shadow (monocular cue)

brighter objects are perceived as being closer than darker objects

perceptual constancy

a tendency to experience a stable perception in the face of continually changing sensory input

stable size, shape, brightness, hue, and location in space

aspects people tend to view objects as having

visual illusion

An apparently inexplicable discrepancy between the appearance of a visual stimulus and its physical reality.

Muller-Lyer Illusion

A famous visual illusion involving the misperception of the identical length of two lines, one with arrows pointed inward, one with arrows pointed outward.

Ponzo illusion

An illusion of size in which two objects of equal size that are positioned between two converging lines appear to be different in size. Also called the railroad track illusion.

Ames Room

A distorted room, first built by Adelbert Ames, that creates an erroneous perception of the sizes of people in the room. The room is constructed so that two people at the far wall of the room appear to stand at the same distance from an observer. In actuality, one of the people is much farther away than the other.

moon illusion

A visual illusion involving the misperception that the moon is larger when it is on the horizon than when it is directly overhead.

auditory system

Responsible for hearing, balance, equilibrium, and communication skills

auditory stimulus

sound waves, created by the compression and decompression of molecules

wavelength of a sound wave

pitch; determines how high or low it sounds

amplitude of sound wave

determines loudness

purity of sound waves

timbre; the complexity of the sound, or how many different frequencies in a sound; affects timbre

frequency

pitch; the number of complete wavelengths that pass a point in a given time

hertz (Hz)

the unit of frequency, equal to one cycle per second

Human Hearing Range

20-20,000 Hz

Decibels

A unit of measurement of loudness

6-10 decibels

Perceived loudness doubles about every ________________

120 decibels or more

Exposure to sounds over this can be painful and may cause damage to your auditory system

purest sound

one that has only a single frequency of vibration

Cochlea

a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses