Dorsal Stream and the Dress (F) Flashcards Preview

II. Neurophysiology and Perception > Dorsal Stream and the Dress (F) > Flashcards

Flashcards in Dorsal Stream and the Dress (F) Deck (25):

What is the idea that your vision can tell you about motion, but only within a certain range of speeds?

perception of change


What controls our perception of size and experiences size illusions?

ventral stream


What controls our interaction with objects? 1. What is this stream's perception of size more like? 2

1. dorsal stream
2. veridical (true), less likely to have illusions


What can damage to the dorsal stream disrupt in terms of perception of objects in space?

1. oculo-centric space
2. head-centered space
3. ego-centric space


What is abnormal motion perception where the patient sees stationary "slide show" instead of motion called? 1. What is damaged in this case? 2

1. akinetopsia
2. MT/V5


What is damage in Balint-Holmes syndrome? 1. What is the triad of findings? 2

1. parietal lobe(s), part of dorsal stream (can be unilateral)
2. optic ataxia (disordered reaching), gaze paralysis, and simultagnosia (can't see more than one thing at a time)


What coordinate system is lost in Balint-Holmes syndrome?

egocentric spatial coordinates


What is disordered reaching called?

optic ataxia


What is not being able to see more than one thing at a time called?



What is thought to be involved in controlling the initiation of saccades under visual attention? 1. What happens when this area is lesioned? 2

1. posterior parietal cortex
2. long-latency saccades (gaze paralysis)


What are the pathways to the dorsal stream that are still intact when V1 is damaged (blindsight)?

1. retina to pulvinar to dorsal stream
2. retina to superior colliculus to pulvinar to dorsal stream
3. retina to konio to dorsal stream


Patient G.Y. that had damage to V1 at age 8, now has stronger connections than normal between what structures of the brain?

LGN to MT/V5


What are the dorsal stream capabilities in blindsight patients?

1. reaching for objects within ego-centric space
2. detecting motion and understanding the direction of moving objects
3. locomotion/mobility within egocentric space


What is the inability to use everyday tools or to carry out skilled, purposeful motor behavior called?

apraxia (dorsal disorder)


What is the inability to use a pencil to draw or copy pictures such as 2D or 3D geometrical shapes, or interlocking figures called? 1. What is this common in? 2. What area of the brain is damaged? 3

1. constructional apraxia
2. Alzheimer's disease
3. parietal


What is the patient still able to do regarding the object presented in constructional apraxia?

1. recognize what is illustrated (not apperceptive agnosia)
2. know what it is (not object agnosia)
3. knows what the overall scheme is (not simultagnosia)


What is it called when a patient cannot understand items on the neglected side and does not interact with them? 1. Where is the lesion? 2. What is it often due to? 3

1. visual neglect (hemi-neglect, unlateral neglect)
2. effect contralateral (usually left side) to lesion (usually right side) in parietal lobe
3. stroke in Middle Cerebral artery


What test is run on all children in our clinic for a full eye exam to evaluate their visual perception?

visual-motor integration test (VMI)


Which develops later according to some investigators, the ventral or dorsal stream?

dorsal stream


How does the camera impact the coloration of "the dress"?

camera makes assumption about the illuminant and adjusts colors to make white white (according to it)


What does the human vision use to determine if the illuminant assigned by the camera to the photo is correct?

the coloration of the skin of the person


What is the main issue with the camera sensors that makes it difficult for it to determine the spectral composition compared to the human eye?

RBG sensors don't overlap in cameras like they do in humans


What is the constant appearance of surface color properties even though the illuminant varies widely called?

color constancy


What are the ideas to explain why color constancy occurs?

1. using the brightest part of the image to determine what the illuminant is
2. using the average of the image to determine what the illuminant is (assuming gray world)


What are people who see the dress as blue doing? 1. As white? 2

1. trying to judge the "light itself" (light arriving at eye) so seeing at as in daylight
2. trying to judge the "dress itself" (spectral reflectance of the cloth) so seeing it as in shade