eye Flashcards
what % of information received by humans from outside world comes from vision?
80
approximately … bits of data enter our eyes every
second
10(8) (100 millions)
The human eye is sensible to light wave which wavelength is roughly between …
400 nm (violet) and 700 nm (red)
which wavelengths are not visible for us?
Wavelengths shorter than 400 nm (ultraviolet, UV) or longer than 700 nm (infrared, IR)
the range of vision is …
infinite
what is the sclera?
the outer covering, a protective tough
white layer
what is the iris?
the colorful, circular muscle that expands
and contracts to control the amount of light that gets
in.
what is the pupil?
a small opening in the iris
Anatomically and developmentally, the retina is known as …
an extension of the CNS
what does the retina consist of?
retinal ganglion cells, the axons of which form the
optic nerve, whose fibers are, in effect, CNS axons
afferent pathways …
bring information from the body to the central
nervous system
efferent pathways …
bring information from the central nervous
system to the body
sympathetic autonomic nervous system …
regulates the heart rate,
rate of respiration, pupillary response and more in alertness states
parasympathetic autonomic nervous system …
stimulates the
body’s “rest and digest” and “feed and breed” responses
visual data from the retinas of the eyes travel to the …. via the …
visual cortex via the thalamus
where is the visual cortex resent/located?
in the posterior region of
the brain, in the occipital lobe
what do both hemispheres have
their visual cortex that gets infos from the opposing eye
information is passed from … to …
from the lateral geniculate to V1
what is the first region of the visual cortex?
V1
where is the information passed to from V1?
to 5 additional stages – V2-V6
what is a saccade?
While we are reading or searching a visual array for a target or simply
looking at a new scene, our eyes move in order to move the fovea (the highresolution
part of the retina) to an area of interest in order to process it in greater
detail.
what is a microsaccade?
Involuntary eye movements produced during attempted visual
fixation.
what is image motion on the retina crucial for?
vision
what does too much motion?
impairs vision
what are blinks?
A semi-autonomic rapid closing of the eyelid. Protect and provides
moisture to the eye.
what is pupil size change?
Dilation and contraction of the pupil. Controlling the amount of
light getting to eye
what did yarbus’ experiments show?
we see that the eye did not move smoothly across the
image or a page while viewing an image or reading a text but that it has erratic
movements with starts and stops, with fixations, inter-fixations, and regressions.
what happens even during gaze fixation?
tiny eye movements continuously occur
what do some of these eye movements have?
dramatic extra-retinal impacts on visual representations, even in
the far periphery
why can’t the eye movements be averaged out in analyses?
these eye movements are not random
aspects of pupillometry (7)
Cognitively driven pupil
modulations reflect certain
underlying brain functions; sexual arousal; emotional intensity; cognitive effort; surprise/uncertainty; noradrenergic system’s locus coeruleus; reward learning mechanisms
measurements (pupillometry) (6)
peak; size average along time window; latency; slope; curve along time window; temporal perspective in
pupillometry studies is focus not only
on how pupil size may change on
average or over the time course of a
trial but also on the dynamic
parameters of change in pupillary
dilation
