Unit 1.2 Part 1 Sensation

Stimulus

any event or situation that evokes a response

Sensory receptors

nerve endings that detect changes in the environment and send signals to the brain

ex: vision → eyes (rods & cones)

Transduction

Process of making physical signals (light waves of chemicals) into neural signals so that the brain can understand (translator)

Sensation

When our senses (like eyes, ears, or skin) detect physical energy from the environment

Bottom-up processing

analysis that begins with the sensory receptors to then send a signal to the brain to process the information

ex: seeing a monster → being afraid

Perception

When your brain organizes and interprets that sensory information to make sense of it

Top-down processing

Brain using what it already knows to understand what you sense

ex: being told something tastes bad before you eat it

Absolute threshold

the smallest amount of a stimulus you can detect at all (something vs. nothing)

Just Noticeable Difference (JND)

The smallest change between two stimuli that you can notice (something vs. something more)

ex: noticing the volume got slightly louder

Weber’s Law

The size of the change you can notice depends on the strength of the original stimulus

Signal detection process

about noticing something (a signal) when there’s a lot of other stuff going on (noise)

ex: hearing you phone buzz while music is playing

Sensory adaptation

Diminishing sensitivity due to constant exposure to a stimulus

ex: sticker on throughout the whole class

Selective attention

focusing attention on a particular stimulus

Cocktail party effect

being able to listen to one conversation with many going on

Inattentional Blindness

failing to see visible objects when your attention is elsewhere

ex: the rock and friends picture

Change Blindness

failing to notice changes in the environment when our attention is focused on a different aspect of the environment

ex: magicians

Vision

eyes receive light energy and change it into neural messages (messages the brain can understand)

Light energy

part of the electromagnetic spectrum that we can see with our eyes

Wavelength

distance between one peak of a wave and the next

what does wavelength determine?

Hue

Hue

the color we actually experience

Intensity

amplitude/height of the wave

• greater the amplitude, brighter the color

• smaller the amplitude, the duller the color

Determines the brightness of the color

Cornea

the transparent tissue covering the front of the eye

• protector of the eye

Pupil

limits the amount of light that enters through the hole (hole)

Iris

circular band of the muscles that controls the size of the pupil (eye color)

Lens

flexible, transparent structure in the eye that changes it’s shape to focus light on the retina

• projector of the eye

Retina

Detects light and turns it into signals for the brain

• the screen

Accommodation

when the lens of the eye changes shape to focus on objects at different distances

Farsighted

only being able to see objects at a far distance

• caused by the eyeball growing too short, or cornea/lens issues

Nearsighted

only  being able to see objects close up

• usually results when the eye is too long or oval-shaped rather than round

Photoreceptor cells

specialized cells in the retina that convert light into electrical signals

ex: boat with islands analogy

Cones

respond to color and fine details

• think: cones-color

• Red, Green, Blue

• fovea

Rods

photoreceptor cells in the retina that help you see dim light and detect black, white, and gray, but not color

• create our peripheral vision

• backup for cones

Bipolar cells

Gather info from the rods and cones and pass the info to the ganglion cells

Ganglion cells

Bundles of axons that form the optic nerve and send the info to the brain

Fovea

the central focal point in the retina, where the cones cluster

• gives you the sharpest and most detailed central vision

Optic Nerve

the nerve that carries impulses from the retina to the brain

Blind Spot

The spot on the retina where the optic nerve leaves the eye, so there are not photoreceptors and you can’t see anything there

Parallel processing

processing of the many aspects of a problem simultaneously

ex: color, motion, form, and depth ALL AT ONCE

Young-Helmholtz Trichromatic theory

the theory that contains 3 different color receptors

• Red, Green, Blue - that combine into any color

Trichromatism

the ability to see the 3 colors and their combinations

• most of us have this (not colorblind)

Color blindness

color deficient vision

Dichromatism

person has only two types of cone cells in their retina that can perceive color

• can only see 2 colors

Monochromatism

a rare eye condition that prevents people from seeing color

• true color blindness

Opponent-process theory

the brain interprets color in opposing pairs

• Red-Green, Yellow-Blue, White-Black

Afterimage effect

after staring at a color, the neurons for that color get tired, so when you look away, you see the opposite colors

Audition

Hearing

Sound

the result of repetitive fluctuations of sound waves hitting into a medium, like air

Frequency

the number of complete wavelengths to pass a given point

• determines the pitch of a sound

Pitch

a town’s experienced highness or lowness

Amplitude - sound waves

the height of the wave which determines the loudness of the sound

Outer ear

the visible _____ and the auditory canal

• collects and funnels sound waves

Middle ear

the eardrum pushes vibrations to the hammer, anvil, & stirrup

Inner ear

cochlea and semicircular canals

• cochlea converts sound to neural signals; semicircular canals help with balance

Cochlea

coiled, fluid-filled bony tube lined by the basically membrane → where the transduction takes place

• snail shaped

Basilar Membrane

a structure inside the cochlea that vibrates in response to sound, helping hair cells (cilia) detect different pitches

Place theory

the brain determines the sound’s pitch by which part of the cochlea is vibrating

• best for high pitches

Frequency theory

what we hear depends of the speed the sound travels up the auditory nerve

• better for low pitches

Volley theory

neural cells taking turns firing to detect medium- to high-pitched sounds

Sound localization

the ear that is closest to the sound will hear a more intense sound

Conduction hearing loss

caused by damage to the mechanical system of the ear

Sensorineural hearing loss

caused by damage to the cochlea’s receptor cells (cilia) or the auditory nerve

Somatic senses

senses that detect touch, pain, temperature, and body position

Touch

a mix of different senses → different skin receptors are activated through specific types of stimulation

What are the 4 distinct skin senses that make up touch?

pressure, warmth, cold, & pain

Gate-control theory

the spinal cord contains a neurological gate that blocks pain signals or lets them through the brain

What substance OPENS the gates by the activity of pain signals?

Substance P

What substance helps CLOSE the pain?

Endorphins

Phantom limb sensation

when the brain lacks normal sensory input, it may misinterpret/amplify spontaneous CNS activity as pain

Kinesthesis

sensory system that monitors the position of individual body parts and movements and reports this info to the thalamus and the cerebellum

Vestibular sense

sensory system that monitors the head position and balance through receptors in the semicircular canals and vestibular sacs in the inner ear

Semicircular canals

three fruil-filled bony channels in the inner ear that provide information about orientation to the brain to help maintain balance

Chemical senses

provide info about the chemical composition of substances before you come into the direct contact with them

Olfactory Stimulation

our sense of smell

• when molecules of a substance are carried through the air to our receptor cells at the stop of our nasal activity

pheromones

chemical messengers that communicate to others of the same species

Anosmia

inability to distinguish between different smells

Gustation

sense of taste, containing taste bud receptor cells that interpret the chemicals signals

What are the 6 main tastes

Sweet, salty, bitter, sour, oleogustis (fat), umami (savory/meat)

Supertasters

have approximately 35 to 60 taste buds per six-millimeter section

• pickier eaters

Medium-tasters

have about 15 to 35 taste buds per section

• 50% of population

Nontasters

have 15 or fewer per section

• don’t taste much

Flavor

combination of taste, smell, and tactile sensations (warmth, texture)