psychophysics

a branch of psychology that examines the relationship between physical stimuli and the psychological responses they elicit in organisms

sensations

features of the environment/basic components we use, to build our experiences

perception

when the brain takes a given message and combines it with previous experience

Bottom-up processing

the neural processing that starts with the physical message or sensations and our initial analysis that prepares the information for use

Top-down processing

occurs when we combine this incoming neural message with our understanding of the world to interpret information in such a way that it has value

Individualistic cultures

focus on individual skills, abilities, and achievements. They believe that it is up to the individual to impact society -Ex) Netherlands, Sweden, Canada, U.S.

Collectivist cultures

focuses on how people working together can achieve more than any individual can alone - Ex) China, Pakistan, El Salvador

Gestalt psychologists

Early German psychologists who proposed a set of "laws" that addressed how humans organize visual information - They believed that we are born with specific, predisposed ways of organizing information so that it has utility

Gestalt principles of organization

outline some fundamental ways to see the world (figure-ground is one example)

Principle of figure-ground

certain information is given priority over the background

Principle of proximity

states that the objects that are close to one another will be grouped together

Principle of similarity

states that objects that are physically similar to one another will be grouped together

Principle of closure

states that people tend to perceive whole objects even when part of that information is missing

Principle of good continuation

states that if lines cross each other or are interrupted, people tend to still see continuously flowing lines

Principle of common fate

states that objects that are moving together will be grouped together

We can only see a tiny range of the light spectrum including

400-700 nm of light

cornea

outermost, transparent protective layer of the eye which is responsible for our ability to focus on objects beyond arm's reach

pupil

a hole in your eye that expands and contracts depending on circumstances

iris

the colorful part of our eye

lens

flexible piece of tissue behind our pupil

accomodation

when the lens refracts light and brings images into focus against the sensory cells in your retina-- determined by the distance of the lens and an object

photoreceptors

transduce light into cellular activity. This is the last time an image can be thought of as electromagnetic energy. Now, it is processed as electrochemical transmissions

Rods

transduce energy into neural language, typically sensitive at lower levels of light. they help to compare early processing about the location of objects and the location of motion in the environment

Cones

communicate information about the wavelength, perceived as color, of an object

fovea

a dense cluster of approximately 6 million cones found directly behind the pupil; they respond best when there is a lot of light

Visual acuity

when cones transmit information about small regions of the retina because only a few cells connect adjacent to ganglion cells

George Statton

a scientist who made a pair of glasses that would flip the world "right-side up" on the retina, making the world appear upside down, but in as little as 87 hours, participants were functionally experiencing regular vision again

after rods and cones react to light they send messages to _____

bipolar cells

bipolar cells add together the firing of several photoreceptors and send a different kind of message to ____

ganglion cells

diffuse bipolar cells

cells found in the peripheral vision which receive messages from as many as 50 rods, sending a singular message to a ganglion cell

Midget bipolar cells

receive input from only a single cone, and this message may be sent to only a single ganglion cell

Small ganglion cells (P-cells)

receive information from the midget bipolar cells. They make up 70% of the ganglion cells in the retina and send signals to the brain about qualities of color and detail

Large ganglion cells (M-cells)

found in the periphery and receive their signals from the diffuse bipolar cells. These signals send information about motion and visual stimuli in the periphery

when a small point of light falls on the center, the center-on cells will ____ their firing rate, while the center-off cells ____ their firing rate

increase, decrease

when a small portion of light hits the surround, the center-on will ____, and the center-off will ____

inhibit, excite

optic nerve

when the message leaves the eye entering the brain where axons of both M- and P- cells are found.

blind spot

a spot on the retina where there are no photoreceptors

optic chiasm

where the axons from each eye are reorganized for more sophisticated processing

lateral geniculate nucleus (LGN)

found in the thalamus and considered the relay center of the brain where the brain first interacts with an actual image

visual striate cortex (VC)

located in the occipital lobe where higher-level processing in the brain occurs and is the location of feature detectors

occipital lobe

where important features of the visual world are assembled and identified

retinotopic organization

the spatial organization that allows for specific points on our retinas to represent certain visual pathways

feature detectors

specialized cells in the VC that respond most actively to specific stimuli

Hubel and Wisel

discovered feature detectors while examining the cortex of cats and monkeys. Using electron recording of single cells in the visual cortex of their animal, they identified one type of feature detector known as a simple cell

simple cell

responds to small stationary bars of light oriented at specific angles-- as the line moves further away from a particular orientation, the cell will change its firing rate

Complex cells

respond to lines of particular orientations that are moving in specific directions. Ex) one cell might increase its firing rate when a vertical line moves from left to right, like when you watch a person walking down the street, but not when the lines move up and down, like when the same person jumps up and down

ventral stream (what stream)

a stream to the temporal lobe where visual information is identified and you know what you are looking at now

dorsal stream (where pathway)

carries visual information to the parietal lobe, where you use the incoming visual information to understand where each aspect is in an image

limbic system

helps to provide the warm, fuzzing feeling you experience when you see a heartwarming image

At what point in the process of going from light to sight does transduction occur?

when photoreceptors change electromagnetic energy to the electrochemical language of the brain. Photoreceptors convert light to neural firing

Longer wavelengths

create the perception of red (~670 nm)

medium wavelengths

produce greens (~530 nm)

shorter wavelengths

create perceptions of blues (~450 nm)

White light

an equal representation of all wavelengths

Short cones (S-cones)

respond maximally to short wavelengths, which we perceive as blue

Medium cones (M-cones)

respond best to greens

Long cones (L-cones)

respond to oranges and reds

Trichromatic theory

proposes that color information is identified by comparing the activation of the different cones. Ex) when you see a blue car, it is because the car is reflecting short wavelengths to your eye, which activate the S-cones but not the M-cones or L-cones.

Image after effect (opponent-process theory)

When you stare at a color for a while, the neurons that respond to that color get tired. When you look away, those neurons fire less, so your brain perceives the opposite color instead (for example, seeing green after staring at red). This happens because color is processed in opposing pairs (red and green) in the visual system, including the LGN of the thalamus.

Pairs of opposite colors:

red and green, blue and yellow, black and white

Monocular depth cues (pictorial cues)

depth cue that requires only one eye

Occlusion

when one image partially blocks the view of a second object, the partially hidden object is seen as farther away than the unblocked object

Relative height

objects closer to the horizon will appear farther away, and the greater the distance between the object and the horizon, the closer the object will appear

Relative size

when two objects are equal size, the one that is farther away will take up a smaller portion of the retina, and the larger object is seen as closer

Scientific American Perspective convergence

as parallel lines move away from us into the distances, they seem to converge or come closer together

Familiar size

when we judge distances based on our knowledge of that objects size

Atmospheric perspective

when more distant objects appear hazy and often have a slight blue tint. This is because as the distance between us and an object increases, the more air particles, dust, pollution, and water droplets occupy the space between our eyes and the object, thus distorting it slightly

Binocular depth cues

depth cue that requires two eyes, making comparisons between the two eyes to understand depth.

Retinal disparity

each eye has a slightly different location on your head, causing each retina to have a slightly different image of the world. Ex) when images become farther away, they have a smaller degree of disparity on the retina.

sound is a _____ energy

mechanical

frequency

the rate of vibrations

intensity

what we perceive as loudness. increased intensity causes the amplitude of the wave to increase, and the wave arrives at our ear with more force.

decibels

what the amplitude of sound waves are measured in

pinna

where sound enters the ear-- the part of the ear you can pierce

tympanic membrane (eardrum)

located in the ear canal

ossicles: malleus, incus, and stapes

three smallest bones in the body which help to amplify the vibrations as sound waves travel further into the inner ear

oval window

transfers vibrations to the bony sound processor of the inner ear

the cochlea

where sound is transduced into the neural language of the brain

basilar membrane

Inside the cochlea; a flexible piece of tissue

Transduction

occurs when the vibrations against the oval window cause fluid inside the cochlea to move

cilia

hair-like projections on sensory hair cells that detect sound and help maintain balance by converting mechanical stimuli into electrical signals for the brain

Inner hair cells (IHCs)

primary sensory receptors responsible for transmitting auditory signals to the brain. They are arranged in a single row along the cochlear spiral and are innervated by approximately 95% of the auditory nerve fibers

Outer hair cells (OHCs)

more numerous and arranged in three to four rows. They perform a mechanical function rather than a strictly sensory one, acting as biological amplifiers to fine-tune incoming sound waves.

Higher frequency sounds will cause the cells ______ to the oval window to excite, while lower-frequency sounds excite the cells ______ in the cochlea

closest, deeper/further

Place theory

The brain uses the location of neural firing to understand the sound; we hear a specific pitch because cells at a specific place on the basilar membrane fire

Frequency theory

states that the brain also uses information related to the rate of cells firing. The more rapidly the cells fire, the higher the perception of pitch

auditory cortex

part of the temporal lobe that processes auditory information

medial geniculate nucleus

in the thalamus where different components of sound are organized and analyzed

tonotopic organization

the spatial arrangement of neurons in the auditory system such that different sound frequencies activate specific anatomical locations-- hierarchical, with simpler sounds, such as pure tones, being processed in lower regions, and more complex sounds, like human speech, being processed higher up

binaural cues

Cues requiring comparisons between information from both ears

Interaural time differences

comparisons made between the arrival time of a sound in each ear (when someone calls your name from the right you hear it in your right ear first, so you know they are to the right of you)

Interaural level differences

the intensity difference of the sound-- after a sound wave reaches the ear closest to the sound, the wave must travel through the head to reach the second ear, and the ear further away from the source of the noise will receive a message that it is less intense

Involuntary musical imagery (earworm)

the experience of an inability to dislodge a song and prevent it from repeating itself in one's head

three basic components in the production of speech

respiration from the lungs, vocal cords, vocal tract

somatosensory system

part of the sensory nervous system responsible for perceiving touch, pain, temperature, body position, and movement, integrating information from the skin, muscles, joints, and internal organs.

McGurk effect

one of the ways the brain understands ambiguous sounds. It illustrates that our auditory perceptions are influence by visual information-- so it's actually easier to understand (and reduce ambiguity) if you can watch their lips as well

Chemoreceptors

where perception of smell and taste begins, it is the only sense that requires you to ingest the physical stimuli in order to analyze the incoming information

the only sense that doesn't go through the thalamus first

smell

Anosmia

the loss of the sense of smell

olfaction

the sense of smell

olfactory mucosa

specialized tissue in the nasal cavity responsible for detecting odors and enabling the sense of smell.

olfactory receptor neurons (ORN)

specialized sensory neurons responsible for detecting odors and transmitting olfactory information to the brain- found in the olfactory mucosa

glomeruli

found in the olfactory bulb they receive messages from ORNs, consolidating all the messages from a particular receptor type

five basic tastes to evaluate food

sweet, salty, sour, bitter, umami (savory)

papillae

little bumps that cover the tongue and is the location of our taste buds

filiform papillae

found over the entire surface of the tongue, giving it the "fuzzy" appearance- they are the only type of papillae that don't contain taste buds

fungiform papillae

on the tips and the sides of our tongue (look like little mushrooms)

Foliate papillae

little folds found along the back of the tongue

Circumvallate papillae

found on the back of the tongue and are shaped like little mounds

taste pore

50-100 taste-sensitive cells found in each taste bud

transduction for taste

when chemical binds to the receptor sites on the taste pore

orbitofrontal cortex (OFC)

where smell and taste are combine, receiving information from the visual "what" pathway as well

bimodal neurons

neurons that respond to more than one sense. they specialize in determining sensations that occur together

Pressure

the physical message of touch

somatosensory cortex

crucial part of the brain located in the parietal lobe, responsible for processing sensory information from the body, including touch, pain, temperature, and proprioception.

mechanoreceptors

located in the skin where information about texture is gathered in four different types of these

Merkel receptor

fire continuously as long as the skin is making contact with an object, sending information about fine details-- high concentration of these in the skin

Meissner corpuscle

fires when the skin first encounters the stimulus and when it is removed

Ruffini cylinder

associated with interpreting the stretching of the skin

Pacinian corpuscle

feels vibration and texture

somatotopic organization

precise mapping of different body regions onto specific areas of the brain. located in parietal lobe and deals with spatial organization in which two adjacent points on the skin are represented.

Sensory homunculus

visual depiction of what our bodies would look life if they were built in proportion to the representation on the cortex

thermoreceptors

in the skin used to sense temperature changes through both hot and cold receptors

Nociceptors

detect pain and send a signal to our brains

Gate-control theory of pain

suggests that impulses that indicate painful stimuli can be blocked in the spinal cord by signals sent from the brain

Small diameter fibers (s-fibers)

fire to damaging and painful stimuli

transmission cell (t-cell)

activated when s-fibers are active, the intensity of the perception of pain in part depends on the excitation of these cells

Large diameter fibers (L-fibers)

send signals to the brain about stimulation that is not painful- when activated they inhibit the activation of the t-cells

placebo effect on pain

people report a significant reduction in pain after taking a pill that has no medicinal properties, suggesting that alleviation of pain is really a result of expectations of pain reduction

Congenital analgesia

a rare condition that has two features: the inability to perceive pain and the inability to perceive temperature • Pain is vital to survive- congenital analgesia results in unrecognized burns, injuries, and infection

Kinesthetic sense

provides us with a basic understanding of where our body is in space and how to move our bodies to accomplish specific tasks - Sense of touch is relied upon and receptors in the joints and muscles both send and receive information about where the body is in space - Information from receptors is sent to the somatosensory cortex-

Vestibular Sense

- our sense of balance - The sensory cells of the vestibular system are located in the cochlea

Semicircular canals

sense changes in acceleration and rotation of the head- hair cells are found in the canal as well that respond to the force of gravity

Vestibular sacs

responds to cues associated with a sense of balance - Motion sickness is closely related to the vestibular system

Case Study of Michael

motorcycle accident leaving his sight very poor, he went through intensive therapy and eventually could recognize numbers and locate things via touch, sound, smell. His verbal memory and new learning were moderately impaired though. his dorsal stream was damaged the most.

transduction

process where environmental sensations are converted into a format the brain can interpret

convergence

example of binocular depth cue relating to the degree to which eyes turn inward to focus

6th taste

a sense identifying when something tastes toxic-- found in a candy which had ammonium chloride in it

contralateral organization

left touch sensation is sent to the right hemisphere and the right touch sensation is sent to the left hemisphere