SensationSensation – Raw data of

experiences, including smells, sights, tastes, touch, balance and pain.The process by which

stimulation of a sensory receptor produces neural impulses that the brain interprets.

The first series of steps in processing of incoming information.

How does stimulation become sensation?Sensory Receptors –

Converts incoming stimulus information into electrochemical signals – neural activity – the only language the brain understands.Example – Light only

reaches the back of your eyes, neurons then carry what your eyes see to your brain.

How does stimulation become sensation?Transduction –

Transformation of one form of energy into another – especially the transformation of stimulus information into nerve signals by the sense organs.Ripe tomatoes would

not appear red without transduction.

Sensory AdaptationSensory Adaptation – Loss of

responsiveness in receptor cells after stimulation has remained unchanged for a while.Example – When a

swimmer becomes adapted to the temperature of the water.

Thus, our sense organs are really just change detectors.

Example – Feed lots in Greeley.

ThresholdsAbsolute Threshold – The amount of

stimulation necessary for a stimulus to be detected.Varies from one person to another.In practice, this means that the presence or

absence of a stimulus is detected correctly half the time over many trials.

Example – Dog Whistle, Smell

ThresholdsDifference Threshold – The smallest amount

by which a stimulus can be changed and the difference detected half the time.Example – Turn up the volume on the TV a very

small amount and your sister says, “You haven’t turned it up enough.” By “enough,” she is referring to her difference threshold.

Example – Frog in hot water.Just Noticeable Difference – Same as the

difference threshold.

ThresholdsWeber’s Law – This

concept says that the size of the JND is proportional to the intensity of the stimulus.The JND is large when

the stimulus intensity is high and is small when the stimulus intensity is low.

Signal Detection TheorySignal Detection Theory – Explains how we

detect “signals,” consisting of stimulation affecting our eyes, ears, nose, skin, and other sense organs.Says that sensation is a judgment the sensory

system makes about incoming stimulation.Often, it occurs outside of consciousness.

In contrast, the older theories from psychophysics, signal detection theory takes observer characteristics into account.

Subliminal SensationsSensations in the outside world that occur

outside our conscious awareness.Do they still influence our thinking?

Example – Pop and Popcorn at a movie.Example – Words in the clouds at a Disney

movie.

Vision

Vision – Parts of the EyeCornea – Where light enters the eyePupil – Opening in the center of the eyeIris – Colored part of the eyeLens – Part of the pupil light passes throughRetina – Light sensitive inner lining of the

back of the eyeball on which light is focusedRetina then contains the receptor cells

responsible for vision.Fovea – Center of the Visual field, area where

images are sharpest.

The RetinaRetina – The thin, light-

sensitive layer at the back of the eyeball. Contains millions of

photoreceptors and other nerve cells.

Photoreceptors – Light-sensitive cells (neurons) in the retina that convert light energy to neural impulses. This is as far as light gets

into the visual system.

Rods & Cones in the RetinaRods – Photoreceptors

in the retina that are especially sensitive to dim light but not to colors.

Cones – Photoreceptors in the retina that are especially sensitive to colors but not to dim light.

FoveaFovea - The tiny area

of sharpest vision in the retina.With movements of

our eyeballs, we use the fovea to scan whatever interests us visually.

Optic NerveOptic Nerve – The

bundle of neurons that carries visual information from the retina to the brain.

Blind SpotBlind Spot – The

point where the optic nerve exits the eye and where there are no photoreceptors.Any stimulus that

falls on this area cannot be seen.

Processing Visual Sensation in the BrainWe look with our eyes, but we see with the

brain.Visual images are imported through the optic

nerve to the visual cortex in our brains, which process the information.

BrightnessPsychological

sensation caused by the intensity of light waves.

ColorColor – Color is not a property of things in

the external world.Rather, it is a psychological sensation created

in the brain from information obtained by the eyes from the wavelengths of visible light.

ColorElectromagnetic spectrum – The entire range

of electromagnetic energy, including radio waves, X rays, microwaves, and visible light.Visible Spectrum – The tiny part of the

electromagnetic spectrum to which our eyes are sensitive. The visible spectrum of other creatures may be slightly different from our own.

Two Ways of Seeing ColorsTrichromatic Theory – The idea that colors

are sensed by three different types of cones sensitive to light in the red, blue, and green wavelengths.

Opponent-Process Theory – The idea that cells in the visual system process colors in complementary pairs, such as red or green or as yellow or blue.

ColorsAfterimages –

Sensations that linger after the stimulus is removed. Most visual

afterimages are negative afterimages, which appear in reversed colors.

ColorsColor Blindness – Typically a genetic disorder

(although sometimes the result of trauma, as in the case of Jonathan) that prevents an individual from discriminating certain colors.The most common form is red-green color

blindness.

Sound and the Ear

The Ear From Coren, Ward, & Enns. Sensation and Perception 6th ed. John Wiley & Sons, Inc. 2004

Outer Ear•Auditory Canal•Eardrum

Middle Ear•Hammer, anvil, stirrup

Inner Ear•Cochlea

Unit IV. Sensaton

and Perceptio

n

Parts of the EarTympanic Membrane – The Eardrum.

Includes 3 tiny bones. Hammer Anvil Stirrup

These bones pass vibrations to the primary organ of hearing, the cochlea.

Parts of the EarCochlea – The

primary organ of hearing.A coiled tube in the

inner ear, where sound waves are transduced into nerve messages. Cochlea then focuses

vibrations on the basilar membrane.

Parts of the EarThe Basilar Membrane – A thin strip of tissue

sensitive to vibrations in the cochlea.Contains hair cells connected to Neurons.When a sound wave causes the hairs cells to

vibrate, the associated neurons become excited. As a result, the sound waves are converted into

nerve activity and carried to the brain (the auditory cortex).

Sensations of SoundPitch – Sensory characteristic of sound

produced by the frequency of the sound wave.

Loudness – Sensory characteristic of sound produced by the amplitude (intensity) of the sound wave

Timbre – The quality of a sound wave that derives from the wave’s complexity.Table 4.3 page 127

DeafnessConduction Deafness

– An inability to hear resulting from damage to structures of the middle or inner ear.

DeafnessNerve Deafness – An

inability to hear linked to a deficit in the body’s ability to transmit impulses from the cochlea to the brain, usually involving the auditory nerve or higher auditory processing centers.

Hearing / Parts of the earEardrum – Hearing begins when sound waves

strike the eardrum and cause it to vibrate.Hammer, Anvil, and Stirrup – Three tiny

bones that hit one another, allowing the vibrations of the eardrum to be carried to the inner ear.

Vibrations then travel to the Oval Window, Cochlea, and Basilar Membrane before they reach the receptor cells in the Organ of Corti and finally reach the brain.

TasteGustation – The sense

of taste – from the same word root as “gusto” – also called the gustatory sense

TasteEvolves throughout life

Babies – Enjoy bland foodAdults – Like novelties (pickles, mustard, ice

cream are all acquired tastes).Flavor vs. Taste

Flavor – Combination of smell and taste.Taste – Sweet, sour, salty, and bitter.

Can still get taste without smell, but can’t get flavor.

TasteTaste Buds – Located on the tip, sides, and

back of the tongue, they are the receptor cells for the sense of taste.Adults – 10,000 taste budsNumber of taste buds decreases with age,

explaining why some elderly people lose interest in food.

Papillae – Bumps on your tongue that house the taste buds.

The Nose and SmellOlfaction – The sense of smellOlfactory Epithelium – Area of the nose that

receives airborne molecules high in each nasal cavity.Receptor Cells in O.E. then send smell to

Olfactory Bulb.Olfactory Bulb – Receives information from

the O.E. and sends it to the temporal lobes of the brain where we then become aware of smells.

The Nose and SmellSmell sensitivity is related to gender and age:

Women more sensitive to smell than men.Young adults have the most sensitive sense of

smell.The older you get the less sensitive you

become to smell.

Pheromones! Humans???

Vestibular and Kinesthetic SenseVestibular – The sense of body orientation

with respect to gravity.Closely associated with the inner ear and, in

fact, is carried to the brain on a branch of the auditory nerve.

Kinesthetic – The sense of body position and movement of body parts relative to each other.

Skin SensesSensory systems for

processing touch, warmth, cold, texture, and pain.Gate Control Theory

– Proposes that we have a neural “gate” that can, at times, block incoming pain signals.

PainServes as a warning signal, telling us that we

have been injured or that something is wrong.

Comes from nerve endingsNo pains / Phantom limb painsIndividuals have different thresholds and

tolerances for pain.