Sensation: the process of detecting a physical stimulus

• ex: light, sound, heat, or pressure

Perception: the process of integrating, organizing, and interpreting sensations

Two types of processing that occur

• bottom-up processing: information processing that emphasizes the importance of the sensory receptors in detecting the basic features of a stimulus in the process of recognizing a whole pattern,

  • also called data-driven processing

  • typically occurs when you’re looking at something new or ambiguous, collecting as much visual information as you can

• top-down processing: information processing that emphasizes the importance of the observer's knowledge, expectations, and other cognitive processes in arriving at meaningful perceptions

  • also called conceptually-driven processing

  • ex. having emotions attached to seeing different people

  • can lead to stereotypes

Sensory receptors: specialized cells unique to each sense organ that respond to a particular form of sensory stimulation (by some form of energy)

• once they detect information transduction occurs

• transduction: a process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system

with sensation involves an absolute threshold: the smallest possible strength of a stimulus that can be detected half of the time, each

• vision: a candle flame seen far away on a clear dark night

• hearing: the tick of a watch at 20ft

• taste: two teaspoons of sugar in 20 gallons of water

• smell: one drop of perfume in a 3-room apartment

• touch: bee wings falling from half an each

difference threshold/just noticeable difference: the smallest possible difference between two stimuli that can be detected half of the time

• ex. turning up the volume parents want it down so you turn it down then they say for it to go up and then the parent tries to turn it down more and the child notices, how much would the change have to be

• Weber’s law: a principle of sensation that holds that the size of the just noticeable difference will vary depending on its relation to the strength of the original stimulus, the size of a just noticeable difference is a constant proportion to the size of the initial stimulus

  • ex. holding a pebble will notice a difference if another pebble is added, if you are holding a heavy rock and the pebble is added you probably won't notice a difference

• signal detection theory: predicts how and when we detect the presence of a fate stimulus or signal, it assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and level of fatigue, if you detect the absolute threshold it depends on a variety of factors

Sensory adaptation: the decline in sensitivity to a constant stimulus

Subliminal perception: the perception of stimuli that are below the threshold of conscious awareness

on quiz :

How We See

We see light which is one of the different kinds of electromagnetic energy that travels in the form of waves a

• wavelength: the distance from one wave peak to another

• we are only capable of visually detecting a minuscule portion of the electromagnetic energy range

Light enters the eye through the cornea: a clear membrane covering the visible part of the eye that helps gather and direct incoming light

pupil: the black opening in the middle of the iris that changes size to let in different amounts of light

iris: the colored part of the eye which is the muscle that controls the size of the pupil

lens: the transparent structure located behind the pupil that actively focuses or bends light as it enters the eye (called accommodation) so that the light falls on the retina

retina: the thin membrane lining the back of the eyeball and contains the sensory receptors for vision: the rods and cones

• rods: long thin blunt sensory receptors of the eye that are highly sensitive to light but not color, they are primarily responsible for peripheral vision and night vision

• cones: the short thick pointed sensory receptors of the eye that detect color and are responsible for color vision and visual acuity

• the rods and cone together transduce light energy into neural impulses

• fovea: small area in the center of the retina composed entirely of cones where visual information is most sharply focused

• ganglion cells: also in the retina, specialized neurons that connect to the bipolar cells these bipolar cells connect the rods and cones to the ganglion cells, and the bundled axons of the ganglion cells form the optic nerve

• optic nerve: a thick nerve that exits the back of the eye and carries visual information to the visual cortex of the brain

• optic disk: in the retina, does not have any rods or cones it's where the optic nerve exits the back of the eye creating a blind spot which is the point at which the optic nerve leaves the eye producing a small gap in the field of vision

optic chasm: the point in the brain where the optic nerve fires from each eye meet and partly cross over to the opposite side of the brain

color vision

color: the perceptual experience of different wavelengths of light color involves three factors: hue, saturation, and brightness

• hue: the property of wavelengths of light known as color different wavelengths correspond to our subjective experience of different colors

• saturation: the property of color that corresponds to the purity of a light wave

  • pure red is measure in a specific wavelength, pink is the measure of 2 wave lengths, the purer a color is the more saturated it is

• brightness: the perceived intensity of a color which corresponds to the amplitude of the light wave

wavelengths are measured in nanometers and every color has a specific nanometer

two theories of different stages of color vision: the young-Helmholtz trichromatic theory and the opponent process theory

• the young-Helmholtz trichromatic theory: the sensation of color results because cones in the retina are especially sensitive to either red light (long wavelengths), green light (medium wavelengths), or blue light (short wavelengths), some overlap of those

  • helps explain color blindness which is one of several forms of color deficiency or weakness in which an individual cannot distinguish between certain colors

    • most common type is red-green to individuals who have this type red and green look the same

  • sometimes just called trichromatic theory

• The opponent process theory: color vision is the product of opposing pairs of color those opposing receptors paris are red green blue yellow and black and white when one color of the color pair is stimulated the other pair is inhibited

  • helps explain the experience of after-image: occurs after the original source of stimulation is no longer present

Brain:

feature-detectors: identified by Hubbel and Wizsel, nerve cells in the brain that respond to specific features of a stimulus such as shape, angle, or movement that the brain assembles into the perceived image

parallel processing: the processing of several aspects of a problem simultaneously, the brain divides a visual scene into sub-dimensions such as color, depth, movement, and form and works on each aspect simultaneously

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what we hear

audition: the technical term for the sense of hearing

we hear sound waves: physical stimuli which are produced by the rhythmic vibration of air molecules that produce our sensory experience of sound, can also be transmitted through other mediums

• loudness: the intensity (or amplitude) of a sound wave that is measured in decibels

• amplitude: the intensity or amount of energy of a wave reflected in the height of the wave, the amplitude of a sound wave determines the sounds loudness

• decibel: the unit of measurement for loudness

  • ex. in library 20 db, air machine alarm clock at 2 ft 80 db, chainsaw and nematic 100 db, jet plane and shotgun 140db, 180 db a rocket launching

• pitch: the relative highness or lowness of a sound which is determined by the frequency of the sound wave

• frequency: rate of vibration or the number of sound waves per second, which is going to affect the pith

• timbre: the distinctive quality of a sound determined by the complexity of the sound wave

how sound waves go through the mechanical process of hearing

• begins as sound waves enter the auditory canal ****of the outer ear which consists of the pinna, auditory canal and eardrum

  • pinna: the skin and cartilage on the side of our head, catches sound waves and funnels them into the ear canal to the eardrum

  • auditory or ear canal: where sound waves pass through and are brought to a point of focus at the eardrum

  • eardrum: tightly stretched membrane that vibrates in response to sound waves

• middle ear: air-filled chamber that amplifies sound waves and consist of three small bones: the hammer, anvil, and stirrup,

  • the hammer, anvil, and stirrup: tiny bones that concentrate the vibrations of the eardrum on the cochleas oval window

  • oval window: a membrane that separate the middle ear from the inner ear whose vibrations are relayed to the cochlea

• inner ear: where sound is transduced into neural impulses and consists of the cochlea, the semicircular canals

  • cochlea: the coiled fluid field inner ear structure that contains the sensory receptors for sound, auditory nerve

    • basilar membrane: membrane within the cochlea that contains the hair cells

      • hair cells: the hair-like sensory receptors for sound that are found in the basilar membrane of the cochlea

  • semicircular canals: play a role in balance

  • auditory nerve: a bundle of fibers that carries nerve impulses from the inner ear to the brain

two theories involved in explaining how we hear different pitches: frequency theory, and place theory

• frequency theory: this is the view that the basilar membrane vibrates at the same frequency as the sound wave

• place theory: the view that different frequencies cause larger vibrations at different locations along the basilar membrane explains higher-pitched sounds

two types of deafness

• conduction deafness/hearing loss: caused by damage, usually to the mechanical system such as the eardrum being punctured or the hammer, anvil, or stirrup losing their ability to vibrate affecting the conduction of sound waves to the cochlea

  • often can be helped with a hearing aid

• nerve deafness/sensorineural hearing loss: caused by damage to the cochleas receptor cells or to the auditory nerve usually linked to biological changes due to aging and prolonged exposure to loud noise

Smell and taste

Smell and taste: linked the sensory receptors for both are specialized to respond to different types of chemical substances

Smell

the sensory stimuli that produce the sensation of an odor are molecules in the air the molecules are emitted by the substance we are smelling

when we smell these substances we inhale them through the nose and through the opening in the pallet at the back of the throat, which is why when you smell a strong odor you can taste it in your mouth,

in the nose, the molecules encounter millions of olfactory receptor cells, when the airborne molecules stimulate them the stimulation is converted into neural messages that pass along their axons whose bundles make up the olfactory nerves directly connect to the olfactory bulb, axons from the olfactory form the olfactory tract these neural pathways project to different brain areas including the temporal lobe and the limbic system

• olfactory bulb: the enlarged ending of the olfactory cortex at the front of the brain where the sensation of smell is registered,

• olfactory receptor cells: constantly being replaced, each cell lasts between 30-60 days

• temporal lobe: involved in our conscious recognition of smells

• limbic system: regulates our emotion response to odors

Taste

our sense of taste results from the stimulation of special receptors in the mouth, the stimuli that produces the stimulation of taste are chemical substances in whatever you eat or drink,

the substances are dissolved by saliva allowing the chemicals to activate the taste buds located on the tongue inside of the mouth and throat

when activated special receptor cells in the taste buds send neural messages along neural pathways to the thalamus in the brain which directs the information to several regions in the cortex

there are four basic taste categories, several others have been identified, but these are the four general accepted: sweet, salty, sour, and bitter

• sweet

• salty

• sour

• bitter

Touch

the skin is the largest and heaviest sense organ for the average adult it covers about 20 square feet in surface area and weighs about 6 pounds

many different kinds of sensory receptors in the skin

• Pacinian corpuscle: important receptor located beneath the skin, when stimulated by pressure the picinia corpulse converts the stimulation into a neural message that is relayed to the brain, if the pressure is constant sensory adaptation occurs because the picinia corpusle reduces the number of signals sent or quits responding all together

pain

pain: sensation of discomfort or suffering that can occur in varying degrees of intensity

pain can be cause by any external stimulus that can produce tissue damage can cause pain including certain chemicals, electric shock, extreme heat, cold, pressure, or noise

pain can also be caused by internal stimuli such as disease, infection, or detention of bodily functions

gate control theory: that pain is the product of both physiological and psychological factors that cause spinal gates to open and relay patterns of intense stimulation to the brain which percieves them as pain

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Kinesthetic Sense: the technical name for the sense of location and position of body parts in relation to one another.

• What lets our body do the variety of motor functions we normally do.

• Proprioceptors: Sensory receptors located in the muscles and joints that provide information about body position and movement.

Vestibular Sense: The technical name for the sense of balance or equilibrium.

• Responds to changes in motion, gravity, and body position.

Perception, Part Two

• “Perception is reality”.

  • If something is repeated often enough, it becomes true

Gestalt Psychology: School of psychology that maintained that our sensations are actively processed according to consistent perceptual rules that result in meaningful perceptions.

• “The whole exceeds the sum of its parts”.

• Figure-Ground Relationship: According to this principle, we automatically separate the elements of perception into the feature that clearly stands out (the figure), and its less-distinct background (the ground).

• Law of Similarity: The tendency to perceive objects of similar size, shape, or color as a unit or figure.

• Law of Closure: The tendency to fill in the gaps or contours.

• Law of Good Continuation: The tendency to group elements that appear to follow in the same direction as a single unit or figure.

• Law of Proximity: The tendency to perceive objects that are close to one another as a unit or figure.

Depth Perception: The use of visual cues to perceive the distance or three-dimensional characteristics of objects.

Binocular Cues: Distance or depth cues that require the use of both eyes.

• Convergence: The degree to which muscles rotate your eyes to focus on an object. The more the eyes converge, the closer the object is perceived to be.

• Binocular Disparity (Retinal Disparity): Because our eyes are set a couple inches apart, a slightly different image of an object is cast on the retina of each eye. When the images are very different, we interpret the object as being close to us. When the images are nearly identical, the object is perceived as being further away.

Monocular Cues: Distance or depth cues that can be processed by either eye alone.

• Relative Size: If two or more objects are assumed to be similar in size, the object that appears larger is perceived as being closer.

• Interposition (Overlap): When one object partially blocks or obscures the view of another object, the partially blocked object is perceived as being farther away.

• Relative Clarity: Far away objects often appear hazy or slightly blurred by the atmosphere.

• Relative Height: Far away objects appear higher in the field of vision.

• Relative Brightness: Objects that are farther away appear to be dimmer than objects that are closer.

• Texture Gradient: As a surface with a distinct texture extends into the distance, the details of the surface texture gradually become less clearly defined.

• Linear Perspective: Parallel lines appear to meet in the distance.

• Relative Motion: When you are moving, nearby objects seem to “zip” by faster than distant objects.

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Perception of motion: involves the integration of information from several sources

• helps us notice and respond to something coming at us

• Phi phenomena: the allusion of movement created when two or more adjacent lights blink on and off in secession, used in Vegas

• stroboscopic motion: used with movies, due to a series of static photographs that are projected onto the screen at the rate of twenty-four frames per second producing the allusion of smooth motion

Perceptual constancy: the tendency to preserve objects especially familiar objects as constant and unchanging despite changes in sensory input

• size constancy: the perception of an object, especially familiar objects as maintaining the same size despite changing images on the retina

  • red van zips past on the highway the van becomes progressively smaller you don’t view it as shrinking, if you put your hand in front of it your hand doesn't suddenly become bigger than the van

• shape constancy: the perception of an object, as maintaining the same shape regardless of the image produced on the retina

  • opening a door and still perceiving it as a rectangle

• brightness constancy: the perception of the brightness of an object remains the same even though the lighting conditions change

  • a white sheet on bed is see as the same brightness in sunlight or a dim nightlight

Perceptual/optical illusions: the misperception of the true characteristics of an object or an image

• the illusion of the shrinking and growing girls (p. 189): two girls that are standing on a checkered floor and it looks like they are crossing paths and it looks like one is growing and one is shrinking

• the Muller-Lyer illusion: visual illusion involving the mis perception involving the length of two lines one with arrows pointed inward and one with arrows pointed outward

• the moon illusion: visual illusion involving the misperception that the moon is larger when it is on the horizon than when it is directly overhead

• interpretation based on experience

  • perceptual adaptation: the ability to adjust to an artificially displaced or even inverted visual feel

    • have a person put on glasses or goggles that say make everything upside down, they will eventually adapt and then they take them off they have to adapt again

Esp extrasensory perception: perception of information by some means other than through the normal processes of sensation the specific field that studied this is parapsychology

• parapsychology: the investigation of paranormal phenomena and abilities

  • telepathy: direct communication between the minds of two individuals

    • demonstration done: two people at a distance or in separate rooms, one person is shown a card then the person that is at the distance is supposed to be able to tell what the other person is looking at

  • clairvoyance: the perception of a remote object or event such as sensing that a friend has been injured in a car accident, you know that something has happened without any information about it

    • mothers and twins

  • psychokinesis: the ability to influence a physical object process or event

    • pocket watch still on a chain and they use their powers and it will start to swing

  • precognition: the ability to predict future events

    • fortune tellers and palm readers