Sense Organs

The first step in knowing

Sound

• Sound waves travel through air• Vibration changes air pressure– called sound waves

• Every sound has pitch and loudness– Depends on frequency (cycle per second)– Low sounds = low frequency– High sounds = high frequency

• Examples– Woman’s voice=shorter vocal chords ; Man’s voice

=longer vocal chords– Violin has shorter strings than a cello

Sound

Sound

• Determined by height (amplitude of waves)– Higher the amplitude the louder the sound

• Amplitude is measured in decibels – Zero dB = absolute threshold for hearing • Ticking watch 20ft away

– 90 db beginnings of hearing loss can occur• Train whistle, lawn mower

Parts of the Ear• Outer ear– pinna (outside of the skull)

• Middle ear – ear drum & bones (hammer, anvil, stirrup)

• Inner ear – cochlea (snail shape tube that contains fluid &

neurons)– Moves in response to vibrations– Movement transmits neural impulses along

auditory nerve to the brain

Hearing & deafness

• Sensorineural deafness–Damage to inner ear– Loss of neurons in cochlea–Result of disease or prolonged exposure to

loud sounds• Conductive deafness–Damage to middle ear–Use hearing aid to increase amplitude

Smell & Taste• Odors are detected by receptor neurons in

each nostril– Info is sent via the olfactory nerve

• Taste has 4 qualities– Sweet, sour, salty, bitter (umami=savory)• Apples & onions taste similar, it is their odor that makes

their flavors different

• Taste buds –receptor neurons– Taste sensitivities can be inherited– Few people ever lose their sense of taste– You grow new taste buds throughout your life

Skin & Touch

• Skin senses are a combination of pressure, temperature & pain– Reduces stress & depression– Can help babies thrive

• Extremities and face more sensitive than thighs, calves, upper arms and shoulders

• Different receptors fire for cold & hot– The more pain receptors in our skin, the more

sensitive the area

How do pain messages travel?

• Pain in contact area ->spinal chord ->thalamus ->projected on to cerebral cortex -> brain registers sensitivity & location -> prostaglandins produce & transmit pain messages to the brain

• Ibuprofin & aspirin stop production of prostaglandins

Why we do or do not feel pain• Gate Theory: rubbing or scratching sends

competing messages with pain messages– Prevents some of the pain messages from getting

through• Phantom pain: people who lose a limb have

memories of pain activated by nerve endings near location of original injury

Perception

Rules of Perceptional Organization

1. Closure– tendency to perceive a whole figure even when

there are gaps.

2. Figure- Ground Perception– The perception of figures against a background– What we perceive as figure and what we perceive

as background influence perception

Figure Ground Illusion

Toblerone Chocolate

Rules of Perceptional Organization

3. Selective Attention– the idea that we are only aware of a small

percentage of what we experience.

– The Door Study

Rules of Perceptional Organization3. Selective Attention– the idea that we are only aware of a small

percentage of what we experience.

Rules of Perceptional Organization

3. Selective Attention– the idea that we are only aware of a small

percentage of what we experience.

– The Door Study

Rules of Perceptional Organization

4. ProximityTendency to group nearby figures together

Rules of Perceptional Organization

5. SimilarityPeople think of similar objects as belonging

together

Rules of Perceptional Organization

6. ContinuityGroup stimuli into continuous patterns

Perception of Movement/ Stroboscopic Movement

• To sense movement, an object must change position relative to other objects

Stroboscopic Movement• Illusions of movement• produced by showing rapid progression of

images or objects that arent moving at all– Flip books

Depth Perception

• Perceived through monocular and binocular cues

1. Monocular Cues: need only one eye to perceive Cause certain objects to appear more distant

from the viewer than others

Depth Perception

2. Binocular Cues:– Need both eyes– Retinal disparity: depth based on difference

between 2 images of object that retina receives as it moves closer or farther away

– Convergence: causes feelings of tension in eye muscle.

The Ames Room

• Observe this room. Take special note of the size, shape, color and details of the room.

• Can one girl really be that much bigger than the other?

The Ames Room Viewer assumes room is

rectangular and the image cast onto the retina is consistent with this hypothesis

• Naïve viewers conclude that one girl is larger, when in fact she is just closer

• Further Reading: http://psylux.psych.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/html/ames_room.html

Optical Illusions

• The perceptual hypotheses that we create become especially striking when they are wrong

• Proximity, Depth Cues, Similarity, and Figure Ground perception affect the hypotheses that we make

• Human perceptions are HIGHLY SUBJECTIVE

Illusion #9A face? A word?

Illusion #10(4) Which word do you see first?

Illusion #11Stare at the center for 15 sec and then look up –

what do you see?

Illusion #11Stare at the center for 15 sec and then look up –

what do you see?

Illusion #13How many black dots are there?

Illusion #16Mind Warp

Illusion #18Impossible Figures (3)

• objects that can be represented in two-dimensional pictures but cannot exist in three-dimensional space

Playing with Words

Perception of letters, words and phrases

Illusion #19Read the following out-loud – now read it

again slowly and see if you fell for the trick

Illusion #20

Illusion #21What do you think?

• Aoccdrnig to a rscheearch at an Elingsh uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht frist and lsat ltteer is at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae we do not raed ervey lteter by it slef but the wrod as a wlohe.

Illusion #22The Stroop Effect

Time yourself saying the word – then time yourself saying the color of the ink. What is the difference?

The Stroop Effect

• The words themselves have a strong effect over your ability to say the color

• There is an interference in the information your brain receives - and this causes a problem

• Speed of Processing Theory– Words read faster that colors are named

• Selective Attention Theory– Naming colors requires more attention than

reading the word• For Further Reading:

http://www.snre.umich.edu/eplab/demos/st0/stroopdesc.html

Stereograms

Bring your eyes close to the screen. As you slowly move your head away from the screen, take

your eyes out of focus and a picture will pop out.

Illusion #23Try your best – what do you see?

Illusion #24And another?

Illusion #25Do you see something floating?

Homework

• Describe how a person’s perceptions affect that person’s point of view. What are some examples of this bias? What role does subjectivity have in your perceptions?