AP Psychology - Unit 1.6a Stimulation Becoming Sensation, Ears, and Eyes

Sensation

• the process of detecting and receiving stimulus information from the environment

Sensory Receptors

• the nerve endings in our sensory organs that respond to the stimuli 

• specific types on different parts of the body

Perception

• our brain trying to make sense of the sensory information

Bottom-Up Processing

• taking sensory data to construct perception

• “what am I seeing?”

Top-Down Processing

• using prior knowledge, experiences, expectations, and ideas to construct perception 

• “is that something I’ve seen before?”

Sensory Transduction

• the conversion of physical stimuli into electrical messages that the brain can understand

Absolute Threshold

•  the minimum amount of stimulus energy that a person can detect at least 50% of the time

Signal Detection Theory

• a framework used to understand how individuals detect the presence of a faint stimulus amid background stimulation 

Subliminal

• used to describe stimuli that is below the absolute threshold 

• individuals are unable to detect this type of stimuli 

Difference Threshold

• also know as the just-noticeable difference

• the minimum difference between two stimuli that a person can notice at least 50% of the time

Weber-Fechner Law

the idea that in order for an individual to detect a difference between two stimuli, the two stimuli must differ by a constant percent, not a constant amount

• percentage displays the change needed in light, weight, or volume in order for a person to notice a difference in stimuli

Sensory Adaptation

• the physiological process of getting used to an unchanged stimulus

• when you are exposed to a constant stimulus over a period of time, your sensory receptors become less responsive to it

Habituation

• the conscious or unconscious process of learning from a repeated stimulus

• results in a decreased reaction to repeated sensory information

Sensory Interaction

our senses do not operate in isolation

• they constantly influence each other to help us understand and respond to the world around us

Synesthesia

a neurological condition where one sense is experienced through another 

creates a cross-sensory experience

• example: seeing colors when listening to music

Sound

• created by the movement of air molecules

Frequency

refers to how fast a sound wave vibrates in a given amount of time

determines the pitch of a noise

• Shorter Wavelengths = High Frequency = Higher Pitch

• Longer Wavelengths = Lower Frequency = Low Pitch

Pitch

• determines the highness or lowness of a sound 

Amplitude

refers to the height of a sound wave

a measure of the physical strength of a sound wave

determines the loudness of a sound

• High Amplitude = Loud

• Low Amplitude = Quiet

Place Theory

• suggests that different pitches stimulate different places on the basilar membrane in the cochlea

• explains an individual’s ability to hear high-pitched sounds

Frequency Theory

• the neurons on the basilar membrane respond with different firing rates that correspond directly to the frequency of a sound wave

• explains an individuals perception of low-pitched sounds

Timbre

• the complex quality of a sound wave that allows us to distinguish between sounds

Volley Theory

• suggests that groups of neurons take turns firing in rapid succession

• helps explain mid-range frequencies

Sound Localization

• the ability to identify the position and changes in position of sound sources

• a complex process that involves the auditory system and several auditory cues to determine the direction and distance of noises

• helps individuals understand where sounds in their environment are coming from

Conduction Deafness

• occurs when there is damage to the outer ear or middle ear

• prevents sound from being properly sent to the inner ear

• the ways in which sound waves are converted to nerve energy have been interfered with or interrupted

Sensorineural Deafness

occurs when there is damage to the inner ear or the auditory nerve that carries sound signals to the brain

caused by;

• aging

• genetic factors

• exposure to loud sounds

Nerve Deafness

• there is a problem with how the impulses from the oval window are sent to the brain

• caused by damage to the auditory nerve or one of the higher auditory processing centers

• people are typically born with this kind of deafness

Cochlear Implant

• a device that converts sounds into electrical signals

Hearing Aid

• amplifies sounds

• allows an individual to hear different sounds around them

Pinna

part of the outer ear

visible, fleshy parts of the ear on each side of the head

two primary functions:

• sound collection - collects and funnels sound waves into the outer ear canal

• sound localization - helps the brain identify the location of a sound source

Outer Ear Canal

lined with a thin layer of skin that contains hair follicles and glands that produce earwax

helps to amplify and focus sound waves

tube-like structure that connects the outer ear to the middle ear

• conducts sound waves from the outer ear to the middle ear

Malleus/Hammer

located in the middle ear

attached to the inside of the eardrum

receives sound vibrations from the eardrum and transmits them to other bones in the middle ear

amplifies sound waves before entering the inner ear

Incus/Anvil

located in the middle ear, behind the eardrum

connects the malleus to the stapes

• receives vibrations from the malleus and transmits them to the stapes

Stirrup/Stapes

located in the middle ear, behind the eardrum

attached to the oval window

receives vibrations from the malleus and incus

• when it vibrates, it pushes against the oval window, creating waves in the fluid-filled inner ear

Cochlea

located in the inner ear

a spiral-shaped structure that is filled with fluid

transduces sound waves into neural impulses that are transmitted to the brain for interpretation

Eardrum/Tympanic Membrane

located at the end of the exterior ear canal

receives sound waves and vibrates

• the vibrations are transmitted to the three bones in the middle ear

Eustachian Tube

narrow tube located on both sides of the head, behind the middle ear

equalizes air pressure between the middle ear and the outside environment

• this ensures proper hearing and prevents ear damage

Semicircular Canals

located in the inner ear

set of three fluid-filled, loop-shaped tubes

responsible for detecting rotational head movements and helping to maintain balance and stable vision

Vestibulocochlear Nerve

located within the inner ear and exits through the internal auditory canal

carries information about our head’s position and movement from the vestibular organs to the brain

Cochlear/Auditory Nerve

• transmits neural signals from the cochlea to the brain

Basilar Membrane

• located within the cochlea of the inner ear

• converts sound vibrations into neural signals by separating different sound frequencies 

Oval Window

• an opening between the middle and inner ear that is critical for hearing 

Retina

a thin, light sensitive layer located at the back of the eye

contains photoreceptors that capture light from the environment

• also contains ganglion cells and bipolar cells

transduction occurs in this structure

Photoreceptors

light sensitive cells that convert light energy into neural impulses

includes;

• rods

• cones

Rods

• allow an individual to see in dim light

• do not provide color information or fine details

• found in peripheral areas of the retina

Cones

• allows an individual to see fine details

• allows for clear vision

• helps an individual see color

• found densely packed in the central part of the retina (fovea)

Bipolar Cells

•  collect impulses from many photoreceptors and shuttles them to ganglion cells

Ganglion Cells

• wired in a way that some neurons are excited by certain colors and inhibited by others

• their axons make up the optic nerve

Optic Nerve

located at the back of the eye

composed of axons from the ganglion cells

extends from the retina

transmits neural signals from the eye to the brain

Blind Spots

we are unaware of our blind spot, because the brain fills in the missing information from the other eye and surrounding area

located where the optic nerve exits the eye

not composed of any photo receptor cells that can detect light

• this characteristic causes this area of the retina to have the inability to capture any visual information

Visual Cortex

• transforms incoming neural impulses into visual sensations of color, form, boundary, and movement

Visible Light

• a form of energy the eyes can detect

• a form of electromagnetic energy

Electromagnetic Spectrum

• the entire range of electromagnetic energy including radio waves, x-rays, microwaves, and visible light

Myopia

• the lens focuses on light in front of the retina 

• distant objects look blurry

• nearsightedness

Hyperopia

• the lens focuses on light behind the retina

• close objects look blurry

• farsightedness

Trichromatic Theory

explains that we see different colors by combining signals from different cones

colors are sensed by three different types of cones

• Blue Cones - Short Wavelengths/Cooler Colors

• Green Cones - Medium Wavelengths

• Red Cones - Long Wavelengths/Warmer Colors

Opponent-Process Theory

 cells in the visual system process colors in complementary pairs

• red-green

• blue-yellow

• black-white

explains color sensation from the bipolar cells onward

this theory explains the phenomenon known as afterimages

Afterimages

• sensations that linger after the stimulus is removed

• happens when you stare at a image for a prolonged period of time, causing the ganglion cells responding to certain colors to become fatigued

Color Blindness

• a condition where an individual has difficulty distinguishing certain colors

• usually occurs when one or more types of cone cells, or the ganglion cells that process color signals, do not function properly

Achromatism

 a disorder that causes problems with color vision

• Complete: individuals cannot perceive any color; they see only black, white, and shades of gray.

• Incomplete: individuals have a reduced ability to distinguish colors, but can still perceive some colors

Dichromatism

a type of colorblindness where an individual is missing one type of cone

• results in the individual becoming confused between certain colors

• most common type is red-green color blindness

Monochromatism

happens when all cone cells are either missing or not working properly

• results in the individual to see everything in different shades of one color (usually black, white, and gray)

Trichromatism

• a type of color vision deficiency where all three types of color-sensing cone cells are present, but one is faulty

Prosopagnosia

• known as face blindness

• people with this disorder can see faces, but can’t recognize who they belong to, even people they know well like family members or close friends

Blindsight

• happens when the primary visual cortex in the occipital lobes is damaged

• individuals with this disorder cannot consciously see or respond to visual stimuli in certain areas

• they can still respond to certain stimuli without conscious awareness, because the brain receives some visual information without conscious awareness

Cornea

• protective outer layer of the eye

• covers the pupil and iris

• bends light to help provide focus

Pupil

• adjustable opening located in the center of the eye

• allows light come through the eye

Iris

a ring of colored muscle tissue that surrounds the pupil

can either dilate or constrict the pupil

iris responds to;

• light intensity

• cognitive state

• emotional state

Lens

• transparent structure located behind the pupil

• focuses light rays into an image on the retina by changing its curvature and thickness

Accommodation

• the lens’ function of changing shape and thickness depending on how far away an object is

Fovea

• central focal point in the retina

• responsible for transmitting light energy into neural impulses

• detects color and fine detail

Aqueous Humor

• clear, watery fluid that fills the anterior chamber

• circulates in the front part of the eye

• provides nourishment

• helps maintain proper eye pressure

Vitreous Humor

• clear, gel-like substance that takes up the space between the eye’s lens and retina

• provides nutrients to the eye and structural support

• helps the eye maintain its spherical shape

Blood Vessels

provide nutrients and oxygen to the eye and inner layers of the retina

remove waste products

primarily found in the choroid

• choroid: layer of tissue within the eye

Ciliary Body/Muscle

located behind the iris

has two main functions;

• produces aqueous humor

• changes the shapes of the lens

External Eye Muscles

• control which way our eyes point, whether it be side-to-side, up and down, or at diagonal angles

• allows us to have depth perception