what is the purpose of vision Flashcards
who proposed the 2 visual systems hypothesis
milner and goodale 1995 and 2006
the 2 visual systems hypothesis
vision for perception
vision for action
what is vision for perception
to develop internal mental representation of our environment
colour, size, shape
what is vision for action
to prepare us for interacting with out environment
able to engage with the real world
patient df
demonstrated visual agnosia
they could not match a card to put it in the slot
they could not estimate the length of a block with thumb and forefinger
but, when asked to pick up a block, their thumb and finger were the correct distance for picking it up
so when asked to use internal mental representation they couldn’t do it but when doing visually guided action, they could
could do vision for action but not perception
what is visual agnosia
inability to identify objects on the basis of shape
can see but cannot recognise or interpret visual information
functions of visual cortex
zeki 1992
zeki 1992
functions of visual cortex
what are the names of the functions of visual cortex
v1 v2 v3 v4 v5/m
what is v1 and v2
primary and secondary visual cortex
earliest processing
cells responsive to colour and form
what is v3
cells respond to form
what is v4
cells responsive to colour and line orientation
what is v5/m
visual motion
patient LM
akinetopsia lesions on part of visual cortex unable to perceive motion greatly difficult to cross roads pouring fluids seem frozen damage in v5/m
what is akinetopsia
patient cannot perceive motion
what are the 2 visual streams
ventral stream
dorsal stream
ventral stream
what stream object processing occipital-temporal-frontal colour texture pictorial detail shape size
dorsal stream
where stream spatial processing location movement spatial transformations spatial relations
what is a visual illusion
our brain trying to make sense of something and sometimes misapplying some of the cues we use to make sense of the world.
Or
because when we look at it, we use vision for perception system when in the real world we use vision for action as interacting with things
haart, carey and milne 1999
vision for perception and action
vision for perception and action
haart, carey and milne 1999
vision for perception and action
study
condition 1-participants indicated length of line using thumb and index finger - vision for perception RESULTS showed strong illusion effect supporting vision for perception
condition 2-participants rapidly grasped target figure using thumb and index finger -vision for action RESULTS showed no illusion effect supporting vision for action
