Sensation & Perception

Sensation: your window to the world Perception: interpreting what comes in

your window

Sensation & Perception

• Sensation: taking in information from environment

• Perception: how we organize & interpret sensory information – allows us to recognize

meaningful events, objects…

The Senses

• Vision• Hearing• Taste• Touch• Smell• Vestibular• Kinesthesis

Ladies, you are

welcome

Vision• Our most dominating

sense• Electromagnetic

energy hits our eyes but we perceive it to be color

• We only see a sliver of the spectrum of electromagnetic radiation

Step 1: Light in the Eye• Light enters the eye through the Cornea

– protects the eye (think plastic cover over camera)

• The amount of light that enters is controlled by the Pupil – opens and closes like a camera shutter

• Pupil is surrounded by the Iris – a ring of colored muscle that dialates/constricts

in response to light intensity– Fun fact: each iris is distinct (scans?)

• Lens is behind the pupil that focuses incoming light rays into an image on the retina

• Accommodation: the process of the lens changing the shape

The Retina• Retina: where the processing visual info begins

(located at back)• Rods: receptor cells that detect black, white, gray,

• peripheral vision, strong in dim light• Bats, rats, mice…

• Cones: receptor cells that detect fine detail & color• Fovea: retina’s area of central focus

– Cones cluster around fovea– Responsible for your detailed vision (driving,

reading…)

Step 2: Transduction• Transduction: the

transforming of stimulus energies (like sights, sounds, smells) into neural impulses our brains can interpret

• Retina sends message to your brain via the optic nerve• Rods/cones->

bipolar cells->ganglion cells-> axons

form…optic nerve->thalamus->occipital lobe (visual

cortex)• Optic chiasma: where the

optic nerves cross

Nearsightedness

Farsightedness

Astigmatism

Step 3: In the Brain• Primary visual cortex in

occipital lobes process info– Color, movement, depth…

at same time!– Parallel processing:

brain processes many parts simultaneously

– Feature Detectors: cells that pick up edges, lines, angles, movements…

– Visual Processing: retinal, feature detection, parallel, recognition

We have specific cells that see the lines, motion, curves and other features of this turkey. These cells are called feature detectors.

Color Vision

Two Major Theories

Trichromatic Theory

Three types of cones:• Red• Blue• Green• These three types of

cones can make millions of combinations of colors

• Does not explain afterimages or color blindness well

Opponent-Process theory

The sensory receptors come in pairs.

• Red/Green• Yellow/Blue• Black/White• If one color is

stimulated, the other is inhibited.

Afterimages

Hearing

Our auditory sense

Parts of the Ear

• Outer Ear: collects & magnifies sounds waves through the ear canal to the eardrum (tight membrane that vibrates with the waves)

• Middle Ear: transmits eardrum’s vibrations through a piston made of 3 tiny bones (hammer, anvil, & stirrup) to the cochlea (snail shaped tube in inner ear)

• Inner Ear: incoming vibrations cause the cochlea to vibrate & jostles the fluid that fills the tube

The Ear

Transduction in the ear1. Sound waves

– enter ear canal – hit the eardrum – hit anvil, hammer, stirrup – Everything is just vibrating!

2. Cochlea vibrates– The cochlea is lined with mucus

called basilar membrane which have hair cells

3. Hair cells vibrate & Organ of Corti turns vibrations into neural impulses 4. Impulses sent by the auditory nerve to the thalamus which sends to the temporal lobe’s auditory cortex

It is all about the vibrations!!!

Pitch Theories

Place Theory and Frequency Theory

Place Theory

• Different frequencies vibrate in different places in the cochlea

• Best explains high pitches

Frequency Theory

• The entire cochlea vibrates at a particular frequency & sends the same quality of sound to the brain

• Best explains low pitches

Deafness• Conduction Deafness

– An injury occurs in outer or middle ear (i.e. eardrum)

• Sensorineural Deafness– The hair cells or nerves in the

cochlea are damaged– Diseases & loud noises can

cause this type of deafness– NO WAY to replace the hairs– Cochlear implant

• electronic device translates sounds into electrical signals send some info about sound to the brain

• Can restore hearing for most adults

Touch• Essential to our development• Receptors located in our skin• 4 basic sensations

– Pressure– Pain– Warmth– Cold

• Gate Control Theory of Pain– Spinal cord contains a “gate”

that either blocks pain signals or allows them to continue to the brain

Kinesthetic Sense• Sense of position

& movement of your body parts

• Receptors located in our muscles and joints– Interacts with vision– Let’s see if this

works!

• Cases of people losing this ability

Click on this to see the story of Ian Waterman

Vestibular Sense

• Our sense of balance & movement

• Our equilibrium is located in our semicircular canals in our inner ears– Sends messages to

cerebellum at back of brain

Taste• Chemical Sense• 5 Taste Sensations:

– Sweet – Salty – Sour – Bitter– Umami (savory meaty

taste)• We have bumps on our

tongue called papillae– Taste buds are located on

the papillae • Sensory Interaction

– Our senses work together to interpret the world around us

– Ex:Smell + texture + taste = flavor

Smell (Olfaction)• Oldest sense, chemical• 5 million receptor cells in

each nasal cavity• Does not go to thalamus,

is oldest sense linked directly to brain (limbic system)– Smell can trigger

powerful memories & emotions

• Women have stronger sense of smell