Sensation and PerceptionGateway to the outside world

Definitions Sensation

The stimulation of sensory receptors and the transmission of sensory information to the Central Nervous System

Perception The psychological

process through which we interpret sensory information

Definitions Absolute threshold

The weakest amount of stimulus that can be sensed

Difference threshold The minimum amount

of difference that can be detected between two stimuli

Absolute Threshold

Definitions

Sensory adaptation The process by which

we become more sensitive to weak stimuli and less sensitive to unchanging stimuli

Definitions Signal-Detection

Theory The method of distinguishing

sensory stimuli that takes into account not only the stimuli’s strengths but also such variable elements as the setting, your physical state, your mood, and your attitudes

Vision How does sight work? What are the main parts of the eye? How does color vision work? What is color blindness and what causes

it?

Vision Vision accounts for

80% of the sensory information processed by the brain

The key component of vision is light

Vision Light is comprised of

electromagnetic waves

The human eye sees a small portion of the spectrum of wavelengths

Visible light can be broken down into its key components

Vision In order from

shortest to longest: red, orange, yellow, green, blue, indigo, violet

The nonvisible ranges include ultraviolet and infrared

Parts of the Eye Pupil

Controls the amount of light that enters the eye

Lens The lens controls the

clarity of the image Retina

The surface upon which the image is projected

Parts of the Eye Photoreceptors

Neurons which are sensitive to light

Information is transmitted via the photoreceptors to the brain

Rods Sensitive to the brightness

of light

Cones Cones provide color vision

Vision

Definition Visual acuity

The sharpness of an image which is determined by the ability to see visual details in normal light

Measured by a Snellen Chart

Vision Measured against

a distance of 20 feet

Numbers show what a person would see against a normal person’s vision

Farsighted vs. nearsighted

Vision Afterimages

Visual impression that remains after the original image is removed

Blind spot Area vision which

is blocked by lack of photoreceptors

How vision works

Color Blindness Some people are unable

to see normal color vision Due to the absence or

malfunction of the cones Most common (99%) is

red-green in which person has difficulty seeing shades of red or green

8% of males and 1% of females

Hearing What two characteristics do every sound

have? What are the main parts of the ear and

how do they work? What are some causes of deafness?

Sound Pitch

How high or low a sound is (frequency)

The frequency depends on the number of cycles per second

The more cycles, the higher the pitch

Sound Pitch is measured in Hertz (Hz) Over the course of time, we lose the

ability to hear different frequency. At age 25, you begin to lose your

ability to hear over 15,000 Hz Take the test

http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearing-test/

Sound Loudness

The loudness of a sound is determined by the height of the sound wave

This is known as the amplitude

Loudness is measure in decibels (dB)

Sound Loudness can be

subjective A person’s

sensitivity to sound and the duration can influence perceived loudness

The Ear

The Ear Pinea

Outer flap of tissue that is use to help funnel the sound to the eardrum

Eardrum A thin membrane that

vibrates when sound hits it Hammer, Anvil, & Stirrup

Small bones in the middle ear which transmit the sound to the inner ear

Stirrup is smallest bone in the body

The Ear Cochlea

Bony tube in the ear that contains the fluids and neurons needed to transmit sounds to the brain

Auditory nerve Nerve that transmits

neural impulses from the inner ear to the brain

Locating Sound Determining

locations of sounds is based upon the principles of stereo sound

The level measured in each ear helps to determine where the sound originated

Deafness May be inherited

or caused by injury, disease or old age

Two primary types of deafness Conductive Sensorineural

Conductive Deafness Occurs due to

damage to the middle ear

Usually aided by devices that amplify sound

Happens when the eardrum is ruptured or through aging

Sensorineural Deafness Caused due to damage

in the inner ear May be mild, moderate

or severe Can be born this way or

due to prolonged exposure to loud sounds

Can be aided by cochlear implants