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Psychology Chapter 4


process that detects stimuli from our body and our environment


process that organizes stimuli into meaningful objects and events

Most Important Senses

vision and audition

6 senses

Vision, Audition, Olfaction, Gustation, Touch, Proprioception


-taking into information by sight through eyes, uses light waves as input.
-transduction of light waves, light is a form of electromagnetic energy that appears as waves lengths


hearing, uses sound waves


molecules that are dissolved on the mucous membrane in the nose


taste, molecules on the tongue (test buds)


touch neurons throughout the skin


sense of body position and movement, balance, input comes from muscle receptors from neurons in the joints and ligaments


Taking sensory information and converting physical properties into to neural impulses:


different physical stimuli are interrupted by distinct sensations because their neural impulses travel by different routes and arrive at different parts of the brain

Sensory reduction

filter incoming sensations and analyze
sensations that sent to the neural impulses (cortex of the brain)

Sensory Adaptation

when constant stimulus is presented for a long period of time, sensations get tired and fire less frequently or even disappears
• Obnoxious odor that you could smell
before is not that noticeable anymore


study of physical stimuli are translated into psychological experiences

Absolute threshold

lowest level of intensity of a given
stimuli that a person can detect half the time

Vision, Hearing, Taste, Smell, Touch

Examples of absolute threshold:

Difference Threshold

the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference. (Also called just noticeable difference or jnd.)

Weber's Law

amount of change in stimulation necessary to produce a JND> constant proportion of the original stimulus

Wave lengths

the distance between two peeks of adjacent waves

Range of visible light

400-750 nanometer (what human eye can


1 billion of a meter

size of wavelength
-shorter wave lengths: violet
-medium wave lengths: blue,
green, and yellow
- long wave lengths: red

Colors are determined by


the membrane of muscle tissue (blue, green) > think of as a diaphragm of a camera, opens and closes

Center of eye pupil expands or contracts

Based on the amount of light the eye pupil...

Lands on the lens

clear elastic disc, shapes the view of the acuity that one holds, objects in distant it stretches lenses to a flat surface, objects that are close become spherical shape

Behind the lens

vitreous humor, holds eye in shape by providing pressure, when get older pieces start to float and black spots appear


light sensitive surface, which have photoreceptors cells
called rods and cones> transduce physical into neural impulses


night vision, black, white, and gray vision, 125 million


color vision (7 million)

Back of the eye

fovea (central focus)
-Made up of 100% cones, connected to bipolar neurons that are connected to ganglion cells

Optic nerve, occipital part of the brain

light is sent from the eye the brain through the


connected to bipolor neurons: which are connect to the ganglion cells


Humans: Round pupils
-From organism to organism changes


light, energy, light waves (reflection of wavelengths and how the mind interprets it)

Additive and Subtractive

2 kinds of color mixing

Primary colors

Red, green, blue

Additive Process

Combining Red, green, and blue lights> equals white light

Paint pigments

magenta, sienna, yellow

Subtractive Process

Magenta (red), sienna (blue), and yellow= no light waves> black light

Isaac Newton

• Colors in response to different wavelengths are not contained in the
rays of light themselves
• Instead colors are created by our perceptual system (in our mind)

Thomas Young:

Trichromatic theory
• Retina has 3 types of color receptors
• Light waves are associated with 3 primary colors

color deficiency

does not have full capacity to see all the

Trichromatic theory

explains vision in the eye itself (back of the retina) fovea

After image

After focusing on an image for a certain amount of time and stare at it> opposing color is now seen in the after image

Opponent- Process Theory

Explains vision between the eye and the brain
o All colors are derived from 3 opposing
o Black and white are opposing colors, deals
with brightest
o Red and green are opposing colors
o Blue and yellow are opposing colors


depends of waves of pressure when an object vibrates


number of sound waves that pass a given point in one second

Sound waves

measured in Hz (measure of frequency)


how high or low sound appears (2000 and 5000 Hz is the normal range for humans)
Low as 20 and high as 20,000


height of sound waves, loudness, measured in dB greater the amplitude> louder the amplitude, perceived loudness every 10 dB


sound quality, mixing of varying sounds (hardly hear pure sounds)


Composed of 3 parts: outer, middle, and inner

Outer ear

• Function: collect sound waves through the pinna (cartilage)
• Travels into the auditory canal to the ear drum (1inch)


• Amplify sound
• Done by three bones > hammer, anvil, and stirrup (called the
ossicles) together they are smallest bones

Inner Ear

• Passed through the oval window (stirrup is right to it)
• Cochlea (fluid lubricates and acts as an agent) organ for auditory
transduction, snail-like
• Neural impulses fed through to the auditory nerve to the thalamus of
the brain


• Baslar membrane: red line of the cochlea
o on top of that are little hair cells
which are called Organ of Corti
(15,000) which are sound waves
transduced to the brain

Temporal lobe

auditory information is sent and processed

Pitch perceptions

Place Theory, Frequency Theory

Place theory

o Place determines the pitch frequency on
the cochlea baslar membrane
o understand of high frequency, but NOT

Frequency theory

o In 1886
o Baslar membrane vibrates at the same frequency as incoming sound wave> which then triggers neural impulses to the brain
at the same rate
-Problem: individual neurons can not
fire more then 1 thousand times per
second Can not explain frequencies
above 1 thousand Hz
-Low frequency sounds

Volley theory

o Neurons work in groups and alternate their firing, not at the same time, combined frequency above 1 thousand times per sound
o 1 thousand and 5 thousand Hz sounds

Olfactory system

• Air borne molecules
• Land on olfactory epithelium> mucous
covered layer of receptors (located in
base of the brain)
- Passes on info to olfactory bulb
- Then sent to the olfactory cortex
to understand aroma (not thalamus)
all senses send info to thalamus
EXCEPT for olfactory
- can recognize 10,000 different
-thalamus: sensory rely station in

Taste (gustation)

Occurs when a substance contacts 10,000 special receptor cells in
the mouth
• Most receptor cells located on the surface tongue (some in throat
and roof of mouth)
• Bumps on the tongue- called papillae

a substance contacts 10,000 special receptor cells in the mouth

Taste Occurs...


-Bumps on the tongue
- where taste buds located
-organ of taste transduction which is the
process of converting physical stimuli
into neural impulses

o 1rst pathway: information being to the thalamus then to the
primary gustatory cortex where taste identification occurs
o 2nd pathway: leads directly to the limbic system and quickly respond to taste limbic system(aggression, anxiety, emotion)
This allow you to spit
something that is toxic before

Taste sensation is transmitted into 2 spots in the brain


-determined by 3 different senses (pressure, temperature, and pain)
• Skin is the largest sensory organ you posses- 5 million sensory
• Not a particular nerve ending, but a lot of nerves firing all at the
same time (pattern)


- Feel by physical exertion on the skin
- Entire body is sensitive to pressure
- Most of the cells in the sensory cortex processing neural impulses from fingers, lips, face, tongue, and genitals (most
sensitive and greatest number of receptor cells)


- Contains two kinds of receptor cells: 1 is sensitive to cold and other to warm
- Austin in 1920 realized> sensation of hot triggered by simultaneous warm and cold receptors


Serves as a warning signal and danger

Gate control theory (how pain is registered)

L and S fibers open and close the gateways for pain to be transmitted in the spinal cord


detect body position and movement

2 phases of proprioception

Kinesthetic and Vestibular


-Provides information about movement, body parts with respect to one another
-Comes from receptors in the muscles, ligaments, and joints
-Without this feedback about where our body parts are located> trouble doing any voluntary movement


-Position of the body (especially the head)
-Controlled by an inner ear structure that controls balance semicircular canal- sends info directly by itself to the auditory nerve, fluid based structure, relation to gravity and balance

Gestalt psychology

Studies how the mind actively organizes sensory stimuli into coherent wholes (pattern)

Form perception

•Process in which sensations are organized into meaningful shapes and patterns
•1 basic rule: figure ground relationship

Laws of grouping (Gestalt)

describe how people group discrete stimuli into meaningful holes


when a figure has a gap, see has a closed figured even though it is not


when we perceive the contour of continuous lines


objects that are near to each other seem to be a unit


elements seem to go together when they are similar

Depth perception

How our brain judges distance (transforms 2D info falls on our retina into 3D perceptions)


depth cues that require info from both eyes


depth cues that require info only from one eye


Shape, size, and color

Size constancy

-retinal size and distance image is from us) called size distance invariance principle
-When the distance to an object increases, the object's retinal size decreases


understand how perceptual systems work

Ponzo illusion

Horizontal lines A and b are equal
Same retinal image size

Mule or Liar Illusion (famous)

Lines A and B equal


An ancient Chinese healing technique in which needles are inserted into the skin at specific points, stimulating the release of pain-reducing endorphins.


A clear membrane covering the front of the eyeball that aids in visual acuity by bending light that falls on its surface.


A thin, flexible membrane at the end of the auditory canal that vibrates in sequence with sound waves.

extrasensory perception (ESP)

The ability to perceive events without using normal sensory receptors.

Feature detectors

Cells in the visual cortex that respond only to a highly specific feature of a visual stimulus, such as a straight edge, an angle, movement of a spot, or brightness.

Induced Movement

The illusory movement of a stationary object caused by the movement of another nearby object.

Moon illusion

A perceptual illusion in which the moon appears larger when near the horizon than when high in the sky.

Müeller-Lyer illusion

A perceptual illusion in which the perceived length of a line is influenced by placing inward or outward facing wings on the ends of lines.


The field that studies ESP and other paranormal phenomena


Airborne chemicals released by animals and detected by other animals using specialized receptors. Pheromones affect the behavior of other animals of the same species.

signal-detection theory

The theory that explains how detection of a stimulus is influenced by observers' expectations.

Sound Localization

The ability to locate objects in space solely on the basis of the sounds they make.

stroboscopic movement

The illusion of movement produced by a rapid pattern of stimulation on different parts of the retina.

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