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The process by which our sensory and nervous systems receive stimuli/info from the environment
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A person’s awareness of the world through their senses.

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The process of selecting, organizing and interpreting sensory information
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How you make sense of your sensory information.

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Information processing that focuses on expectations and experiences in interpreting incoming sensory information

TRANSDUCTION
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Transforming signals into neural impulses.
Information goes from the senses to the thalamus , then to the various areas in the brain.
Sensory Adaption:
Decreased responsiveness to stimuli due to constant stimulation.
Coctail-Party Effect (phenomenon)
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Ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations.
Form of selective attention .

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Stimulus (input) is light energy
Is the dominant sense in human beings.
The process involves several steps:
Step 1:
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Gathering Lightlight is reflected off of objects and gathered by the eye

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Cornea- transparent protective coating over the front part of the eye
Pupil small opening in the iris through which light enters
Iris-colored part of the eye
Lens- transparent part inside the pupil- focuses light onto the retina
Retina lining of the eye containing receptor cells sensitive to light.

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Receptor cells- respond to a specific energy
Rods- receptor cells in the retina- night vision, brightness
(black/white) PERIPHERAL vision
Cones- receptor cells in retina- color vision
Fovea- area of the retina that is the center of the visual field- Also the most clear vision.
Optic nerve- bundle of axons and ganglion cells- carry neural messages from the eye to the brain
Blind spot- no receptors- where the optic nerve leaves the eye
Optic Chasm- place at base of the brain where some fibers from the optic nerve cross to the other side of the brain.

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Visual cortex located in the occipital lobe
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VC receives impulses from cells of the retina that activate feature detectors
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Dr. Huble and Dr. Weisel: groups of neurons in the VC respond to different types of visual images
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VC has feature detectors for vertical lines, curves, and motion
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Our visual perception is a combination

Three types of cones:
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Red
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Blue
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Green
These three types of cones can make millions of combinations of colors.
Does not explain afterimages or color blindness well.

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Either/or response of the three color receptors
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Sensory receptors organized in pairs
(red/green, yellow/blue, black/white)
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If red is stimulated, green won’t fire.
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Explains the color after images and color blindness

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A combination of both explains color vision completely
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Colorblindness- partial or total inability to perceive hues
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Trichromats- have normal color vision
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Monochromats- totally colorblind
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Dichromats- blind to red/green or blue/yellow

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Stimulus/input is sound waves
Ears contain structures for hearing and balance
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Amplitude- height of a sound wave that determines loudness- measured in decibles

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Number of complete waves per unit of time
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Dogs can hear sounds at higher frequencies than humans can
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Hertz (Hz)- cycles per second= measue of the frequency of waves

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Pitch- auditory experience corresponding primarily to frequency of sound vibrations resulting in higher or lower tones.
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Decibel- the magnitude of a wave- determines loudness.

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Ear canal- aka auditory canal
Eardrum- aka tympanic membrane
Hammer, anvil and stirrup- small bones in the inner ear relay eardrum to the inner ear
Cochlea- contains fluid that vibrates causing the basilar membrane to vibrate
Basilar membrane- inside the cochlea- contains sense receptors for sound
Organ of Corti- Contains receptor cells
Auditory nerve- bundle of neurons that carries signals from the ears to the brain.

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Sound waves hit the eardrum then anvil then
hammer then stirrup then oval window.
Everything is just vibrating.
Then the cochlea vibrates.
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The cochlea is lined with mucus called basilar
membrane.
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In basilar membrane there are hair cells.
When hair cells vibrate they turn vibrations into neural impulses which are called organ of
Corti.
Sent then to thalamus up auditory nerve.

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Place Theory- Different hairs vibrate in the cochlea when they different pitches.
So some hairs vibrate when they hear high and other vibrate when they hear low pitches.
Frequency Theory- All the hairs vibrate but at different speeds.
More focused on the lower tones.

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Conductive- sound vibrations from tympanic membrane are blocked (wax, fluid build-up, infection, abnormal bones growth) REPLACE THE
BONES OR HEAING AIDS
Sensorineural – damage to auditory nerve (head injury, birth defects, LOUD NOISES, high BP)
COCHLEAR IMPLANTS- CAN’T REPLACE THE
HAIRS!!!
Prebycusis- changes in the inner ear- common in old age
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Tinnitus- constant ringing or roaring sound.
Cause may not be found.

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When skin is indented, pierced, or experiences a change in temperature the sense of touch is activated.
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Pain: Gate control theory
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Spinal cord has a neural “gate” to block or allow pain signals to the brain

 Pain tells the body that something has gone wrong.
Usually pain results from damage to the skin and other tissues. A rare disease exists in which the afflicted person feels no pain.: CIPA

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Taste buds papillae-bumps on your tongue
We sense four tastes: sweet, salty sour, and bitter
All others are a combination of the basic 4
Umami recently discovered comes from glutamate (like MSG)
Different parts of the tongue detect all types

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Olfaction
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Smell the nose and brain work together to “smell”
Chemical molecules enter the nose, dissolve in mucous within a membrane called the olfactory epithelium that contains receptor cells sensitive to odors. Located about 7 cm up the nose in the nostrils
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Pheromone– chemical the communicates info to others through smell

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Why do some smells trigger memories???
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Where are memories primarily stored?

 When one sense affects another sense, sensory interaction takes place. So, the taste of strawberry interacts with its smell and its texture on the tongue to produce flavor.

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VESTIBULAR SENSEtells us about how the body is oriented in space
Responsible for balance
(head and body’s position)
Semicircular canals- located in the inner ear sensitive to body rotation
Vestibular Sacs- inner ear responsible for sensing gravitation, forward, backward and vertical movements
KINESTHETIC SENSE
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System for sensing position and movement of individual body parts
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Senses of force and movement of muscles
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Stretch receptors- sense muscle strength and contractions

•The minimum stimulation necessary for a person to detect a particular stimulus 50% of the time. (see table for examples) AKA Detection

Sub Threshold = BELOW the minimal stimulus needed… AKA Subliminal messages

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AKA: Just Noticeable Difference (JND)
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The smallest amount of change that a person can detect between two stimuli 50% of the time.
Absolute Threshold vs. Difference Threshold
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If you put your hand on a burner and turned it on, the first time you felt something would be Absolute Threshold and the second you noticed it getting hotter would be Difference Threshold.

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Weber’s Law – detection of a stimulus depends on the original stimulus itself.
Example: If a 300 lb. person loses 20 lbs and a 120 lb. Person loses 20 lbs, which one would you notice lost the weight first?
(120 lbs because 20 lbs is a larger % of their body weight)
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AKA- Difference Threshold

Signal Detection Theory
Investigates effects of distractions and interference on perceptions. Detection depends on:
1. Stimulus variables (how weak or strong the stimulus is)
2. Environmental variables (what’s going on around you)
3. Organismic variables (Your own experience, expectations, motivation and alertness)

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Focusing conscious awareness on a particular stimulus to the exclusion of others
The ability to focus on one stimulus at a time
Allows a person to function in a world filled with many stimuli
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People with ADD have trouble doing this.
*** THE COCTAIL PARTY EFFECT

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Perceptions about objects change from moment to moment. We can perceive different forms of the
Necker cube; however, we can only pay attention to one aspect of the object at a time.
Necker Cube

Perceptual Organization
Gestalt Rules
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 When vision competes with our other senses, vision usually wins – a phenomena called visual capture.
 How do we form meaningful perceptions from sensory information?
 We organize it. Gestalt psychologists showed that a figure formed a “whole” different than its surroundings.

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Form Perception- figure ground
Proximity- close objects are perceived as being in the same group
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Similarity- objects that look similar are perceived to be in the same group
Continuity- continuous forms are perceived as the same group.
Closure- Closing in gaps on familiar objects
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Similar to top down processing

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Depth perception enables us to judge distances.
Gibson and Walk (1960) suggested that human infants (crawling age) have depth perception. Even newborn animals show depth perception.
Visual Cliff

Visual ability to adjust to an artificially displaced visual field, e.g., prism glasses .
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Retinal Disparity
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Stereoscopic Vision
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Distance cue based on the difference between the images
Eyes don’t perceive the exact same image
(peripheral vision)
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Combining two retinal images to give a 3-dimensional perception.
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Overlap in the center- the brain connects them into one image
Convergence: Neuromuscular cues. When two eyes move inward (towards the nose) to see near objects and outward (away from the nose) to see faraway objects.

Monocular Depth Cues –Visual cues requiring use of one eye
Linear Perspective
Relative Size

Texture Gradient: Indistinct (fine) texture signals an increasing distance- Course objects appear to be closer.
Shadowing- areas in shadows appear farther away
Relative Clarity (Ariel Perspective) the further away the less clear object appear to be
Motion Perception: Objects traveling towards us grow in size and those moving away shrink in size. The same is true when the observer moves to or from an object.
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In this example, the passenger is moving past a stable world. If she fixes her gaze on the bridge, objects behind it will appear to move forward. The farther away the object is, the more slowly it will appear to move. Objects in front of the fixation point appear to move backward.

Phi Phenomenon: When lights flash at a certain speed they tend to present illusions of motion.
Neon signs use this principle to create motion perception.
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Perceiving objects as unchanging even as illumination and retinal images change. Perceptual constancies include constancies of shape and size.
Shape Constancy
Don’t forget :
Color Constancy
Lightness
Constancy

The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues.
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Both girls in the room are of similar height.
However, we perceive them to be of different heights as they stand in the two corners of the room.
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Both photos from S. Schwartzenberg/ The Exploratorium

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The Ames room is designed to demonstrate the sizedistance illusion.

 Immanuel Kant (1724-1804) maintained that knowledge comes from our inborn ways of organizing sensory experiences.
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 John Locke (1632-1704) argued that we learn to perceive the world through our experiences.
How important is experience in shaping our perceptual interpretation?

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Blakemore & Cooper (1970)
Kittens raised without exposure to horizontal lines later had difficulty perceiving horizontal bars.

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Our experiences, learned assumptions and beliefs shape our experiences
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ALLPORT AND POSTMAN
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Streetcar scene of a black man talking to a white woman. He is holding a knife.
The subjects tell the story (like telephone) to another person.
The typical story told by the last person included the black man holding the knifecentral theme in many trials.

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Leveling- the perceiver DROPS certain details because they don’t fit his/her cognitive categories or assumptions.
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Sharpening- details of the story that are consistent with the values and interests of the perceiver are emphasized
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Assimilation- padding and organizing are used to make the central theme fit expectations

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All what we perceive not only comes from the environment but also from our minds. Schemas or concepts develop through experience

Human Factor Psychologists design machines that assist our natural perceptions.
The knobs for the stove burners on the right are easier to understand than those on the left.
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Most would say no.
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Scientists tend to agree
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What about ESP (Extrasensory
Perception)?