7/28/2019 Botton Up vs Top Down http://slidepdf.com/reader/full/botton-up-vs-top-down 1/14 Top-Down versus Bottom-Up Perception • Top-Down – Perceive the whole and then individual parts as needed. – Experience-driven as opposed to stimulus or input- data driven. – Quick and highly inferential but also a source of misperception. • Bottom-up – Perceive the individual parts and organize them into a whole, if possible. – Information available in the stimulus itself. Arranged by Dr. Gordon Vessels 2005
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• Marr wanted to understand mechanismsof vision rather than just behaviorsassociated with it.
• …he wanted to link neurophysiologywith psychology.
• He took an information processing viewof the mind…
• …and aimed to describe perception interms of computations on sense data…
• …to extract high level visual experience.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
19th Century demonstrated manydifferent ways in which we can group
objects.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
• After gaining information aboutgroupings and surfaces, the viewer needssome spatial information.
• Marr called this stage the 2½D Sketch toemphasis that this stage does not give afull 3D representation.
• Rather, just an estimate of the spatiallocations of objects and materials inrelation to the viewer.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
• The final stage of Marr’s theory. • A full 3D description of our spatial
environment involving the
identification of the structure of objects and materials in our visualfield.
• It allows us to work out the 3Denvironment from a non-egocentric
point-of-view.
Source: Bell, Vaughan (2004). Perception and perceptual distortion. A PPT presentation retrieved athttp://www.cardiff.ac.uk/psych/home/bellv1/ Used here with the author’s written permission. Slide arrangement by Vessels, 2005.
Primary source Bell, Vaughan (2004). Perceptions and perceptual distortions, a PPT show accessed athttp://www.cf.ac.uk/psych/home/bellv1/conf/VaughanPerceptionLecture2004.ppt#1. Written permission granted 5-5-05.
If all of these people were at the same football game, who among them was most likely tohave perceived what actually happened on a controversial play where the receiver mayhave fumbled the ball before his knees touched the ground? Whose perceptions were themost bottom up? Whose perceptions were the most top-down and thus influenced andquickened in terms of inference by their present needs, biases, and heightened emotion?
Whose perception may have been the most accurate and objective based on his or herknowledge of the game? When the head referee reviewed the replays, did he use top-down or bottom-up perception primarily? What top-down influence may have made itpossible for his perceptions to have been highly accurate? Did these people literally seesomething different? Do they really believe what they claimed to have seen?