Psych 101 Chapter 41 What’s that smell? Do you hear that noise? Taste this! Look at me! Feel this, isn’t it soft? We use these phrases because of our

Psych 101 Chapter 4 1

What’s that smell? Do you hear that noise? Taste this! Look at me! Feel this, isn’t it soft?

• We use these phrases because of our senses. Without us even knowing, our sense organs (nose, eyes, ears, tongue, and skin) are taking in information and sending it to the brain for processing.

• Both people and animals get all of their knowledge from their senses, and that is why our senses are so important.


Prologue to Senses

• Human life would be very different without the ability to sense and perceive external stimuli

• Imagine your world without the ability to see, hear, smell, touch, and feel

• Psychologists are interested in sensation and perception as inputs to and outputs from the brain


Sensation: Receiving messages about

the world

• There are five types of senses:

Sense Organs Sensory Receptors Neural Impulses

Occipital Gustatory

OlfactoryAuditory Tactile


Sensation: Receiving messages

• Stimuli: What messages can be received?

–Anything capable of exciting a sensory receptor cell can be defined as a “stimulus”

–Examples include: sound, light, heat, cold, odor, color, touch, and pressure


Sensation: Receiving messages

• Transduction: Translating messages into the brain’s language– Sense organs transduce sensory energy into

neural (bioelectrical) energy– Converting one type of energy into another type is

the process of transduction– Your brain only deals with bioelectrical impulses so

transduction must occur; what cannot be transduced cannot be a stimulusGate Control Theory


Homeostasis > Keeping Balance

• Sensory limits: How strong must the message (signal) be for it to be detected by the sensory receptor?

– Absolute thresholds– Difference thresholds JND also known as Weber’s Law

– Sensory adaptation and habituation

– Study of these sensory limits and phenomena is called “Psychophysics”


Protection• The eyebrows are strips of hair above your eye,

which prevent sweat from running into them. • Eyelashes help keep the eye clean by collecting

small dirt and dust particles floating through the air.

• The eyelids sweep dirt from the surface of the eye, and protect the eye from injury.

• Tears are sterile drops of clean water, which constantly bathe the front of the eye, keeping it clean and moist.


Vision: Your human camera

• The eye: How does it work?– The transduction of light wave/particles into

neural energy is carried out by the receptor cells in the retina of the eye

– The retina has 2 general types of cells that engage in transduction

• rods (for transducing black/white light)• cones (for transducing colored light)


Sense-Sational Facts!• Most people blink every 2-10 seconds.• Each time you blink you shut your eyes for .3

seconds, which means your eyes are closed 30 minutes a day from blinking.

• A new born baby sees the world upside down because it takes some time for the baby’s brain to learn to turn the picture right-side up.



• What is it and how does it work?

– Color is the conscious experience that results from the

processing of light energy of differing frequencies by the eye

and the brain– You are told your colors as a

child: you could have just as easily have been told red is blue. So color is created by the brain!!

It is cognitive!


Vision: Your human camera

–The “Trichromatic Theory” – 3 cone types: red, green, and blue cones

• similar to the RGB setup on your color TV• red cones detect red, blue detect blue, etc.• problems exist in this theory however because

there is no known mechanism in the brain for blending the three colors into the rich hue of color that we can see


The “Opponent-process Theory”– 3 cones types (similar to trichromatic theory)

but each of the three have opponent processes (unlike trichromatic theory)

– Red-green cones, blue-yellow cones, and black-white cones Christmas, Spring, Ying-Yang

– After-images and inversions of color, e.g., sunset after-images, attest to the probability that the opponent-process theory is correct


Hearing:Auditory

– sense that detects vibratory changes in air sound waves

– sound waves are changes in air pressure– throwing rock into still lake will give a picture of sound waves


Hearing: Sensing sound waves• Sound: What is it?

– Sound waves are measured by the frequency & amplitude• frequency: pitch/note

• amplitude: loudness/decibels• Place Theory

• Frequency Theory



Sense-Sational facts!

• Children have more sensitive ears than adults, and can recognize a wider variety of noises.

• Dolphins have the best sense of hearing among all animals. They can hear 14 times better than humans.

• Animals hear more sounds than humans.• When you go up high elevations, the change in

pressure causes you ears to pop.


Body Senses: Messages from myself about myself

• Orientation and movement senses– Vestibular organs

• located in the inner ear, there are movement detectors and orientation detectors

semi-circular canals provide orientation detection or rotary movement detection

processes involved in detection of movement in vestibular organs


Body Senses

• Kinesthetic senses– located in the muscles, joints,&

skin, they provide information about

your movement in space, posture, &

orientation in space


Pressure, Temperature, Pain



Sense-Sational Facts!

• You have more pain nerve endings than any other type.

• The least sensitive part of your body is the middle of your back.

• The most sensitive areas of your body are your hands, lips, face, neck, tongue, fingertips, and feet.

• There are about 100 touch receptors in each of your fingertips.

Psych 101 Chapter 4 23–chemical “lock/key” sensation

10,000 taste buds


Sense-Sational Facts!• We have almost 10,000 taste buds inside our mouths;

even on the roof of our mouths.• Insects have the most highly developed sense of taste. They have taste organs on their feet, antennae,

and mouthparts.• In general, girls have more taste buds than boys.

• Taste is the weakest of the five senses.• Cats cannot taste sweet!


smell is connected well to our memory


Sense-Sational Facts!• Dogs have 1 million smell cells per nostril and their

smell cells are 100 times larger than humans.• People who cannot smell have a condition called

Anosmia.• If your nose is at its best, you can tell the difference

between 4000-10,000 smells. • As you get older your sense of smell gets worse.

Children are more likely to have better sense of smell than their parents or grandparents.

• Babies are born with an acute sense of smell.

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Psych 101 Chapter 41 What’s that smell? Do you hear that noise? Taste this! Look at me! Feel this, isn’t it soft? We use these phrases because of our