sensation and perception

what is sensation

the process by which our sensory organs receive stimulus energies from the environment

what is perception

neural processing of electrical signals to form internal mental representations inside the brain of what is on the outside

what is transduction

transformation of stimulus energy from the environment into neural impulses

what is top-down processing

Cognitive process where your brain uses pre-existing knowledge, memories, expectations, and context to interpret incoming sensory information 

what is bottom-up processing

How our brains interpret sensory information directly from the environment, starting with raw details and building up to a complete perception without relying on prior knowledge, context, or expectations

what is psychophysics

set of methods to objectively measure people's subjective perceptual experience by focusing on the relationship between the physical characteristics of environmental stimuli and our mental experience of them

what is gestalt psychology

describes how the brain automatically groups sensory elements into organized wholes using rules like connectedness, closure, continuity, similarity, proximity, and synchrony

what is figure-ground principle

School of psychological thought that attempted to explain how various elements group together to form objects, arguing that perception is more than a simple piecing together of building blocks

what is proximity

we see objects as grouped when they are close together 

what is similarity

tend to group together objects that look alike

what is closure

mentally fill in gaps to see complete shapes

what is good continuation

tend to follow smooth, continuous patterns rather than lines/paths that have abrupt changes in direction

what is common fate

tend to group together objects that move or change in the same direction at the same speed

what is blindsight

Seen in patients with damage to the primary visual cortex

what is visual agnosia

failure to recognize objects in spite of the ability to see them

what is prosopagnosia

a neurological or developmental disorder characterized by an inability to recognize the identity of faces despite normal vision and intelligence

what are the components of the eye

pupil, iris, lens, retina, accommodation, fovea

where is a pupil

a hole in the iris where the light enters the eye 

where is an iris

coloured muscle circling the pupil

where is a lens in an eye

membrane at the front of the eye that focuses the light on the retina 

where is a retina

surface at the back of the eye that contains the photoreceptors

where is an accommodation in an eye

adjustment of the lens thickness by specialized muscles in order to change the degree to which it bends light

where is a fovea

small, central pit in the retina where cone photoreceptors are densely packed, allowing for the sharpest visual acuity

function and structure of retina

a multi-layered surface that hosts the photoreceptors of the eye

structure of fovea

has cells and photoreceptors

names of photoreceptors in fovea

rods and cones

names of cells in fovea

bipolar and ganglion

function of photoreceptors

convert light energy into electrical energy  

function of cells in bipolar and ganglion cells

fire action potentials when stimulated sufficiently, and these electrical signals converge in a bundle of axons: optic nerve, to go to the brain

function of optic nerve

bundle of axons that converge from the retina and transmit action potentials to the brain

where is the optic nerve located

Connects to the eye in a specific spot at the back of the retina, and there is no room for photoreceptors where the optic nerve leaves the eye: the blind spot

function of rods

Photoreceptor cells that support nighttime vision; provide sensitivity 

function of cones

Photoreceptor cells responsible for high-resolution colour vision; specialize in acuity

distribution of rods and cells

120 million rod, 5 million cone

location of cones

densely clostered in a small central pit in the back of the retina: fovea

location of rodes

farther from the fovea and toward the periphery of the retina

where is the blind spot

an area in the middle of the visual field where no photoreceptors are located and no info can be received

what are on-centre-off-surround retina ganglion cells

fires when light hits the centre of their field and are held back by light on the surround, so they pick up contrast and edges.

what are the two visual pathways

left, right

when can you see from the left visual pathway

when light goes to the right retina and right hemisphere

when can you see from the right visual pathway

when light goes to the left retina and left hemisphere

what is the optic chiasm

where it goes when visual information travels along the optic nerve from each eye to the brain and information from each nerve diverges.

what is the lateral geniculate nucleus

the thalamus's visual relay station, passing signals from the retina onto the primary visual cortex; stop between the optic chiasm and the primary visual cortex.

where is the lateral geniculate nucleus in this picture

the green dot on the thalamus

what is another name of the visual striate cortex

primary visual cortex

function of visual striate cortex

where signals from the LGN first reach, and basic features like edges and orientation are processed.

where is the visual striate cortex

the first region of the cerebral cortex that processes visual information

where is the occipital cortex

visual processing region at the back of the brain in the occipital lobe

function of occipital cortex

where the primary visual processing happens

what is a feature detector

a single cell recording that measures action potentials directly from individual neurons to determine that certain neurons in the primary visual cortex respond to basic features represented across the retina: edges, lines, and angles with specific colours/movements 

what are the two pathways at the back of the brain

ventral and dorsal

what are the ventral and dorsal pathways

 two tasks that reflect two major pathways in the visual brain

function of the ventral pathway

from occipital lobe along the underside of the temporal lobe, addressing the “what” question

function of the dorsal pathway

from occipital lobe upwards and joins the parietal lobe, addressing the “where” and “how” questions.

what supports location, depth and motion while influencing how we interact with objects

dorsal pathway

what happens when ventral pathway is damaged

impairs recognizing what an object is but is able to say where it is (visual agnosia)

what happens when dorsal pathway is damaged

can see and recognize without knowing where it is or how to grasp it 

what is the visible light spectrum

narrow band of electromagnetic waves between about 390 and 750 nm that our eyes can detect

What is the shortest wavelength colour on visible light spectrum

purple

what is the longest wavelength colour on visible light spectrum

red

what is the trichromatic theory

Hypothesis that there are three types of receptors that produce our perception of a multicoloured word

what are the three light wavelengths which are our primary colours

red, green, blue

which of the three primary colours has the longest light wavelength

red

which of the three primary colours has the shortest light wavelength

blue

what is opponent process theory

cone responses are combined in the bipolar and ganglion cells into opposing pairs (red vs. green, blue vs. yellow), so we perceive colour partly by what it is not, which explains why staring at one colour produces an afterimage of its opposite. 

what are the properties of sound

pitch, amplitude

what is pitch

perceptual quality of a sound that makes a flute sound high and a tuba sound low

what is ampiltude

related to the quantity of energy and the intensity/loudness of sound we hear 

what is the anatomy of the ear

outer ear, middle ear, inner ear, ossicles, cochlea, basilar membrane

structure/function of outer ear

the part of the ear that is visible to the naked eye is the pinna, which is a sound funnel attached to the side of the head that has evolved its shape to capture sound waves and has an ear canal, which then enhances certain sound frequencies and protects the eardrum

structure/function of middle ear

the air-filled section between the outer and inner ear where the eardrum vibrates with sound waves and passes those vibrations through the three ossicles (hammer, anvil, and stirrup) to the oval window, amplifying them along the way.

structure/function of inner ear

the innermost part of the ear where the cochlea resides; behind the oval window and is full of fluid, which requires more energy to move 

structure/function of cochlea

fluid-filled, spiral structure of the inner ear where the ossicles’ pushing and pulling on the oval window makes the basilar membrane vibrate, turning those vibrations into neural signals.

what are the hair cells in ears called

cilia

function of cilia

Vibrations of the basilar membrane causes them to bend back and forth which triggers neural impulses

amount of cilia in each ear

10 000

function of auditory pathway

processes sound waves from the inner ear through specialized brainstem nuclei to the temporal lobe

how do we interpret sound

through place theory, frequency theory, signals traveling to primary auditory cortex and then tonotopic organization

what is place theory

the theory of pitch perception: different pitches arise from stimulation at different places along the basilar membrane

what is frequency theory

theory of pitch perception: the brain uses the frequency of auditory sensory neuron firing to indicate pitch

what happens at the primary auditory cortex

located in the temporal lobe, where sound is processed

function of tonotopic organization

organizes auditory cortex so that nearby frequencies are processed near each other in the brain-> sound map

how to know where sound is coming from

interaural time difference

what is an interaural time difference

there is a difference in the arrival time of a sound at two ears, so when sound comes from one side, it will reach the nearer ear faster than the farther ear. Because of this, the brain can determine sound location

what is a somatosensory pathway

how specialized receptors in the body, each tuned to a specific stimulus like touch, pain, temperature, or vibration, send detailed information to the brain so we can perceive and respond to sensations from inside and outside the body

what is a sensory homunculus

a map of the body in the brain, where each body part’s size reflects how much cortex is devoted to it, so sensitive areas like the hands and lips look huge.