after midterm-moon Flashcards
how can size perception be ambiguous?
large, distant objects can have same retinal image size as smaller, nearer objects
retinal image size is measured in terms of
visual angle (thumb at arms length ~ 2 degrees)
distal stimulus
real, physical stimulus (e.g. actual height of the people)
proximal stimulus
information available to our sensory receptors (e.g. retinal image); not distal stimulus
visual angle gets __ as object moves closer to eye
larger
when distal stimulus is constant, proximal stimulus ___ when stimulus moves
changes
judgement based on proximal or distal size when deciding if tower or flower pot taller?
distal size (cuz proximal size is same in the photo)
size constancy
ability to see an object as unchanged in size despite change in retinal image size as object moves; familiarity contributes
size-distance scaling
when we (unconsciously) estimate an object’s distance & size, then adjust our perception of size to be consistent with our distance judgment
Bayes’ theorem
mathematical model of how prior knowledge can influence estimates of the probability of a current event; in vision, predicts how visual system decides what you see (e.g. pennies)
bite out of penny least likely cuz
have to explain through accidental viewpoint
prior probability as applied to purple/green rectangle with B on top
probability that a particular stimulus ever happens regardless of what we are looking at (part of Bayes’ theorem); (full letter placed on top rather than divided in half)
observation consistency as applied to purple/green rectangle with B on top
hypotheses A & C more consistent with observation (both end up with B on top)
Emmert’s Law
perceived size = retinal image size * perceived distance
T/F: someone without stereopsis can’t experience the big/small monster illusion
false; since this is flat and relies on pictorial depth cues, can see this in one eye (no binocular disparity)
when burning image of circle onto retina, afterimage appears smaller on close surface compared to wall because
perceived size = retinal image size * perceived distance; proximal stimulus is the same so it looks bigger further away than closer
when cues to distance are removed, size constancy fails which means that size perception is based more on _____ ___ alone
proximal size
what does Emmert’s law predict on Holway & Boring (1941) experiment (circle matching)
small (large) test circles match to small (large) test circles
physical size: in emmert’s law, perceived size based on
perceived distance
visual angle: perceived size based on
proximal size only
size constancy fails when
few distance cues, objects too far away to judge distance (sun & moon)
size-distance scaling illusions
Ames room, Ponzo illusion (horizontal lines between vertical/diagonal lines), moon illusion, Muller-Lyer illusion
size-distance scaling explanation of Ames room
smaller vs larger proximal size of people, peephole removes depth cues, linear perspective cues to distort room, both corners appear same distance away;
-perceived size = proximal size (no perceived distance)
size-distance scaling explanation of Ponzo illlusion
same proximal size; depth cues and flanking lines make top one look further away; perceived size = perceived distance (no proximal size)
size-distance scaling explanation of moon illusion
distal size, distance & proximal size of moon are constant; lack of depth cues make moon look closer & thus smaller overhead; perceived size = perceived distance (not proximal size)
if look at moon through peephole, then
illusion goes away
size-distance scaling explanation of Muller-Lyer illusion
vertical line looks closer and perceived shorter; vertical line looks farther and perceived longer (explains moon illusion); perceived size = (not proximal size?) perceived distance?
problems with size-distance scaling explanations for Ponzo, Moon, & Muller-Lyer illusions
-elements misperceived as larger do not usually look farther away
-depth cues do not always cause us to misperceive size
tilt constancy theory
tilted flanking lines make ends of bottom horizontal line look closer together than top horizontal line (vertical line should tilt the opposite direction as the tilted lines)
tilt constancy theory can better explain ___ illusion
Ponzo
conflicting cues theory
can’t isolate parts from whole figure; arrowheads included in size judgment (muller-lyer)
conflicting cues theory can better explain ___ illusion
Muller-Lyer
T/F: depth reversal illusion not related to size-distance scaling illusions
true
depth reversal illusion demonstrate _____ influences on depth perception
top-down
