S11 AND S12 sensation and perception

sensation

process of which our sensory organs receive stimulus energies from the environment and transduce them into electrical energy of the nervous system

perception

the neural processing of electrical signals to form an internal representation inside your brain of what is on the outside

transduction

the process where specialized sensory receptors convert physical energy from the environment

top-down processing

Your brain uses pre-existing knowledge, context, and expectations to interpret incoming sensory information

bottom-up processing

we begin to perceive new stimuli through the process of sensation, and the use of our schemas is not required.

psychophysics

the scientific study of how physical energy in the world (like light, sound, or weight) → mental sensations and perceptions

gestalt psychology

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

figure-ground principle

the brain’s ability to separate an object (figure) from everything else around it (ground)

proximity

Grouping objects based on how close they are

similarity

we group together similar objects

closure

we fill in the gaps to create continuous edges → perceive an objects as a whole

good continuation

we tend to look for smooth, continutious patterns in objects

blindsight

patients with damage to the primary visual cortex/V1 can respond to visual stimuli without conscious awareness

can accurately predict object movement and spacial location

visual agnosia

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

prosopagnosia

a type of associative agnosia, inability to identify faces

lesion further from V1, can copy but not identify (asso. agnosia)

lens in the eye

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

retina

a surface at the back of the eye that contains the photoreceptors

fovea

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

optic nerve

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

blindspot

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

rods

photoreceptor cells in the retina that primarily support nighttime vision

cones

photoreceptor cells that are responsible for high-resolution colour vision

bipolar cell in the retina

connect photoreceptors (rods and cones) to ganglion cells

ganglion cells in the retina

specialized neurons that carry visual signals from the photoreceptors to the brain via the optic nerve

distribution of rods and cones

Cones are concentrated in the fovea centralis. Rods are absent there but dense elsewhere. Far more rods than cones in the retina.

visual pathway

visual signals carry through the optic nerve into optic chiasm (where the visual signal from the left eye goes to the right hemisphere and opp.) → lateral geniculate nucleus (thalamus) → V1 → occipital cortex where the signal is interpreted into something meaningful

feature detector

specialized cells in the visual cortex that respond to basic features such as lines, edges and angles

ventral pathway

what? object perception in the inferotemporal cortex that specialized in form, colour and object recognition

dorsal pathway

where/how?: spacial location, movement and visually guided actions in the posterior parietal cortex

trichromatic theory

there are three types of cone cells (s-cones, blue light; M-cones, green light; L-cones,red light) each most sensitive to a wavelength of light

they work together to produce our perception of a multicoloured world

additive colour mixing (trichromatic theory)

process of creating new colours by combining different wavelenghts of light (primary colours typ so red, green, blue)

opponent process theory

information from the cones is seperated into three sets of opponent channels in the ganglion cell layer

Opponent cells: blue-yellow opponency and red-green opponency

the properties of sound

pitch/frequency and amplitude (intensity of loudness of the sound)

middle ear

the eardrum and ossicles (hammer, anvil and stirrup that amplify incoming soundwaves)

inner ear

the cochlea resides, of which’s liquid vibrate on the basiliar membrane at the same frequency of the sound heard

hair cells

basiliar membrane that have auditory sensory neurons

primary auditory cortex

temporal lobe, where sound is processed

interpreting sound

tonotopic organization: nearby frequencies are processed near each other in the brain, forming a sound map

sound localization

interoral time difference: difference in arrival time of a sound at the the two ears

somatosensory pathway

includes specialized sensory receptors that are each tuned to detect a specific type of stimulus e.g. for pain, temperature → together providing detailed infromation about the external/internal environment

sensory homunculus

a distorted visual map of the human body laid across the brain's primary sensory cortex