PAM Task 5 Visual streams and scale errors
Learning goals:
1. Development and function of visual streams
2. Scale errors and link to visual streams
Two cortical visual systems
These two areas receive independent sets of projections from the striate cortex, the what and
where depends on processing of different kinds of visual information. The separation between
magno and parvo information in the cortex is not as distinct as initially thought. When
movements become more automatic, the ventral stream becomes less involved and is replaced
by more streamlined circuitry in the dorsal stream (subcortical).
Ventral stream (what) Dorsal stream (where/how)
V1 sends projections to the inferotemporal cortex V1 sends projections to the posterior parietal cortex
(parvocellular, what)
parvocellular Magnocellular
Object-centered: identity of object doesn’t change, the Viewer centered: egocentric, position relative to own
interpretation is abstract, orientation of bject does not body, scaling, motion, surface and contour
matter
abstract representations of the visual world, which can acts in real time, guiding the programming and
then not only serve to provide our immediate visual unfolding of our actions at the instant we make them;
experience but also be stored for future reference. By thus enabling smooth and effective movements. The
this means the ventral stream enables us to think about visuomotor activities to which it contributes do benefit
the world, recognise and interpret subsequent visual from experience, even though it does not have visual
inputs, and to plan our actions ‘offline’ memories.
What we see is not necessarily what is in charge of our actions. This dissocation between
perception and action: proven by illusions, like the hollow face. Knowledge of what faces
look like impels observers to see the inside of a mask as if it were a normal protruding face.
Despite the fact that observers could not resist the illusion, actions that they directed at the
face were not fooled. Thus, when they were asked to flick off a small target stuck on the face,
they unhesitatingly reached out to the correct point in space. This demonstrates a
simlutaneous engagement of 2 parallel visual systems, each wit hits own version or reality.
Learning goals:
1. Development and function of visual streams
2. Scale errors and link to visual streams
Two cortical visual systems
These two areas receive independent sets of projections from the striate cortex, the what and
where depends on processing of different kinds of visual information. The separation between
magno and parvo information in the cortex is not as distinct as initially thought. When
movements become more automatic, the ventral stream becomes less involved and is replaced
by more streamlined circuitry in the dorsal stream (subcortical).
Ventral stream (what) Dorsal stream (where/how)
V1 sends projections to the inferotemporal cortex V1 sends projections to the posterior parietal cortex
(parvocellular, what)
parvocellular Magnocellular
Object-centered: identity of object doesn’t change, the Viewer centered: egocentric, position relative to own
interpretation is abstract, orientation of bject does not body, scaling, motion, surface and contour
matter
abstract representations of the visual world, which can acts in real time, guiding the programming and
then not only serve to provide our immediate visual unfolding of our actions at the instant we make them;
experience but also be stored for future reference. By thus enabling smooth and effective movements. The
this means the ventral stream enables us to think about visuomotor activities to which it contributes do benefit
the world, recognise and interpret subsequent visual from experience, even though it does not have visual
inputs, and to plan our actions ‘offline’ memories.
What we see is not necessarily what is in charge of our actions. This dissocation between
perception and action: proven by illusions, like the hollow face. Knowledge of what faces
look like impels observers to see the inside of a mask as if it were a normal protruding face.
Despite the fact that observers could not resist the illusion, actions that they directed at the
face were not fooled. Thus, when they were asked to flick off a small target stuck on the face,
they unhesitatingly reached out to the correct point in space. This demonstrates a
simlutaneous engagement of 2 parallel visual systems, each wit hits own version or reality.
