3: Senses Flashcards
Doctrine of Specific Nerve Energies
the nature of a sensation depends on which sensory fibers are stimulated, not how
senses
vision hearing touch/pain taste smell kinesthesis (body position) vestibular system (body movement)
environmental stimulus
1
everything in the environment that we an potentially perceive (electromagnetic radiation/light, pressure changes in the air/sound, mechanical pressure, temperature, airborne molecules, ingested water-soluble molecules)
attended stimulus
2
a particular stimulus that is focused on making it the center of attention
stimulus on the receptors
3
ex) electromagnetic waves -> photoreceptors of eyes
perceptional process
stimulus
- environmental stimulus
- attended stimulus
- stimulus on the receptors
electricity
- transduction
- transmission
- processing
experience/action 7. perception 8. recognition 9. action knowledge
transduction
4
physical stimulus -> neural signal
transmission
5
neural signals -> activate other neurons which active more neurons
processing
6
electrical signals undergo neural processing (involves interaction between neurons)
perception
7
conscious sensory experience
recognition
8
our ability to place an object in a category
action
9
includes mother activities such as moving head/eyes and locomotion through the environment
perceptual set
a mental predisposition to perceive on thing and not another
knowledge
any info that the perceiver brings to a situation
sensation
process by which sensory receptors/nervous system receive and represent stimulus energies from the environment
bottom-up processing
starts at the sensory receptors and works up to higher levels of processing
perception
process of organizing/interpreting sensory info, enabling the human to recognize meaningful objects/events
top-down processing
constructs perceptions from the sensory input by drawing on experience/expectations
thresholds
.
sensory coding
.
intensity
.
quality
.
adaptation
.
rate of firing
how nervous system codes stimulus intensity
greater rate = more intense
also through
sensory quality
how the nervous system represents the difference between modalities (vision and hearing) and within modalities (low vs high pitched sound, bitter vs sweet)
specificity coding
representation of specific stimuli by the hiring of neurons that are specificied to respond to just these stimuli (the grandmother neuron)
distributed (pattern) coding
the representation of specific stimuli by the pattern of firing of many neurons
sensory adaptation
process where the sensitivity to a stimulus declines if the stimulus is presented for an extended period of time
wavelength
distance over which the wave’s shape repeats (peak to peak/trough to trough)
photons
quantum of electromagnetic radiation
hue
dimension of color that is determined by the wavelength of light
intensity
amount of energy in a light or sound wave which we perceive as brightness or loudness
determined by amplitude
ganglion cell axons
60% cross chiasm
40% continue on same side
form on each side of optic tract
terminate in primary visual or striate cortex or V1
cornea
transparent “window” into the eyeball (ca. 13mm) seres as simple fixed lens that begins to gather light and concentrate it)
iris
colored, smooth muscle ring controlling size of the pupil
crystalline lens
lens inside the eye which enables changing focus, can change the shape (altering the focus of the retinal image)
pupil
where light enters the eye, size is. controlled by reflex (bright - contracts up to 2mm, dark dilates up to 8mm)
retina
light sensitive membrane in the back of the eye that photoreceptors which receive an image from the lens and send it to the brain through optic nerve
photoreceptors
cells in the retina that initially transduce light energy into neural energy
rods
photoreceptors specialized for night vision (90 million)
cones
photoreceptors specialized for day vision, fine visual acuity, and color (4-5 million)
pigment
any substance that absorbs light
photopigments
differ in wavelength at which they absorb light most efficiently cones: purple S- green M- red L-
receptive field
area of retina that influences firing rate of ganglion cell when stimulated
excitatory influence
increases firing rate
inhibitory influence
decreasing firing rate
on-center cell
depolarizes in response to an increase in light intensity in its receptive field (RF) center
off-center cell
depolarizes in response to an decrease in light intensity in its receptive field (RF) center
where pathway
visual areas in the dorsal stream -> parietal lobe -> process info relating to location of objects and actions required to interact
what pathway
visual areas in the ventral stream -> temporal lobe -> process info relating to object recognition
cross-talk
anatomical connections between pathways
modularity
specialization of certain cortical areas for specific visual qualities
module
particular structure of the brain that contains a large proportion of neurons that respond selectively to a particular quantity
middle temporal (MT) cortex
module for movement
inferotemporal (IT) cortex
module for form
primary cells
respond best to stimuli like slits/spots/ellipses/squares
elaborate cells
respond to complex stimuli like specific shapes/combined with color/texture
specificity coding
representation of specific stimuli by firing of neurons that are specified to respond to just these stimuli
distributed coding
representation of specific stimuli by the pattern of firing of many neurons
