Motion Flashcards
(41 cards)
motion
change in position/location over time
motion aftereffect (MAE)
the illusion of motion in a stationary object after prolonged exposure (adaption) to movement
evidence of interocular transfer - can adapt one eye and still get after image in other
opponent process system
apparent motion
brain assuming same object is showing up in a different place after it disappeared from another place
2 ways we perceive motion from what we already know
motion detection cells
- particular cells taking info from eye, V1, etc. to digest motion
where pathway
periphery is quite good at _______ ______, meaning this part of the LGN is also good at this
detecting motion; Magnocellular layer
where the where path ends
parietal cortex
___ cells can code for motion
V1
issue with having only V1 cells to detect motion and the solution
response would be similar for actual motion vs. two separate images in those receptive fields
solution: add additional system to calculate timing
delay cells
as they sound, serve to process a delay from cell 1
multiplication cells
only fire when D1 (delay cell of cell 1) and cell 2 simultaneously fire
aperture problem
when you (or cells) can only see small window (aperture) of the world, it can become hard to know how objects are moving
through window we see one motion while the whole picture shows us a different motion, true with gratings as well
shows us that we can’t rely on a couple of V1 cells to understand motion alone
what part of the brain has an impact on ability to detect global motion when damaged?
hMT (human middle temporal cortex)
another term for hMT (bonus points if you know what cortex this can be categorized as)
V5; extrastriate cortex (V+#)
akinetopsia
motion blindness
- vision is like a set of still images; for some, kind of like strobe lights or more severe. leaves after images!
caused by damage to hMT
some drugs result in ___ __________ (type of motion blindness)
acute akinetopsia
first-order motion
changes in luminance over space/time
second-order motion
changes in contrast or texture where overall luminance stays the same
________ motion seems to be particularly priviledged, why?
biological; this is because the motor regions of the brain that is activated when recognizing are the same regions that are involved in the action itself
optic flow
the changing angular position of points as we move through space
focus of expansion (FOE)
center point from which motion seems to expand outward from
though to be how pilots start the process of landing a plane by focusing on whether the runway is expanding symmetrically
time-to-collision (TTC)
helps you decide whether something is coming at you/if you need to move out of the way
optic flow gives much of this information
tau
size of retinal image relative to expansion rate
basically a heuristic estimate of whether an object is rapidly expanding and taking up a lot of retinal image
motion induced blindness
not full blindness, but motion can cause static parts of an image to seemingly vanish
static dots will wink out
tied to global position
motions of our eyes
fixations
- when our eyes are focused on one area
saccades
- when our eyes move sharply between points
micro-saccades
- even when we are fixated, our eyes are making small movement adjustments (preventing fading/adaption)
smooth pursuit
- when our eyes steadily follow motion
reflexive eye movements
- automatic eye movements, e.g. when you move your head without changing fixation
vergence
- rotating eyes inward (converge) or outward (diverge)
