Unit 5: Sensation & PerceptionVision and Hearing

Transduction

• Transduction- (transform) changing one form of energy into another– All Senses

• 1) receive sensory information through receptor cells• 2) transform it into neural information• 3) deliver that information to the brain

I. VisionThe Stimulus Input: Light Energy• Wavelength the peak to peak

distance in a sound or light wave• Relationship to frequency…

– Hue the color we experience due to the dominant wavelength of a light

• Amplitude height of the wave– Intensity (brightness)

Electromagnetic Energy Spectrum

The Physical Property of Waves

The Eye• Cornea

• Pupil

• Iris

• Lens– Accommodation- the process by which the eye’s lens changes

shape to focus near or far objects on the retina.

• Retina– Optic nerve– Blindspot– Fovea

The Structure of the Eye

The Structure of the Eye

Describe the function of each part listed.

The EyeThe Retina

• Rods and Cones

RodsCones

Which is which?

• retinal receptors that detect black, white, and gray

• necessary for peripheral and twilight vision, when cones don’t respond

• retinal receptor cells that are concentrated near the center of the retina

• that function in daylight or in well-lit conditions

• detect fine detail and give rise to color sensations.

Rods versus Cones

The Retina’s Reaction to Light

The EyeThe Retina

• Optic nerve

• Blind spot

• Fovea

Visual Information ProcessingVisual Cortex

Pathways from the eyes to the visual cortex

Visual Information ProcessingFeature Detection

• Feature detectors– Hubel and Weisel

Visual Information ProcessingParallel Processing

• Parallel processing–Blind sight (a strange phenomenon)

Visual information processing

Visual information processing

Visual information processing

Visual information processing

Visual information processing

Color Vision

• Color Blindness– Gender differences?

–Monochromatic vision

–Dichromatic vision

How do we perceive color?

Young-Helmholz (trichromatic) Theory

• the retina contains three different color receptors which, when stimulated in combination can produce the perception of any color– 3 color receptors =

• one most sensitive to red

• one to green

• one to blue

Opponent-Processing Theory• opposing retinal

processes) enable color vision– red-green– yellow-blue– white-black

• For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.

After image

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Hearing

The Stimulus Input: Sound Waves

• Audition

• Amplitude–loudness

• Frequency– Pitch- a tone’s experienced highness or

lowness

The structure of the ear

The ear is divided into the outer, middle and inner ear.

Outer Ear

• Outer ear–Pinna

–Auditory canal

–Ear drum

Outer Ear: Eardrum

Eardrum

Middle Ear

Bones of the middle ear = the hammer, anvil, stirrup which vibrate with the eardrum

Oval window = where the stirrup connects to the cochlea

Inner Ear

Cochlea = a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.

The Ear

• Inner ear– Oval window

–Cochlea• Basilar membrane

–Auditory nerve

–Auditory cortex

The structure of the ear

Review what each structure does

Neural impulse to the brain

The EarPerceiving Loudness

• Basilar membrane’s hair cells–Compressed sound

Cochlea and loud sounds

The EarPerceiving Pitch

Place theory- theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated – High pitched sounds

• Frequency theory- theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch– Low pitched sounds

• Volley principle

The EarLocating Sounds

• Stereophonic hearing

• Localization of sounds–Intensity

–Speed of the sound

Hearing Loss and Deaf Culture

• Hearing loss–Conduction hearing loss

• Damage to structures (bones, eardrum)

–Sensorineural hearing loss• Damage to hair cells

–Cochlea implant

• Signing– Deaf Culture controversies

Other Senses: Touch, Taste, Smell

Touch

• Types of touch–Pressure

–Warmth

–Cold

–Pain• Sensation of hot

Touch

• Rubber hand illusion

Touch

• Kinesthesis- the system for sensing the position and movement of individual body parts

• Vestibular sense- the sense of body movement and position, including the sense of balance– Semicircular canals

Semicircular Canals

PainUnderstanding Pain

• Biological Influences– Noiceptors– Gate-control theory

• theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain.

– “gate” is opened by the activity of pain signals traveling up small nerve fibers– is closed by activity in larger fibers or by information coming from the brain.

– Endorphins– Phantom limb sensations– Tinnitus

The pain circuit

PainUnderstanding Pain

• Psychological Influences– Rubber-hand illusion– Memories of pain

• Social-Cultural Influences

Biopsychosocial approach to pain

PainControlling Pain

• Physical methods

• Psychological methods

Taste

• Sweet, sour, salty and bitter–Umami

• Taste buds–Chemical sense

• Age and taste

TasteSensory Interaction

• Sensory interaction- the principle that one sense may influence another, as when the smell of food influences its taste.

• Interaction of smell and taste– McGurk Effect

• Interaction of other senses

Smell

• Olfaction–Chemical sense

–Odor molecules

–Olfactory bulb

–Olfactory nerve

Smell (olfaction)

Smell and age