de.mpg.escidoc.pubman.appbase.FacesBean
English
 
Help Guide Disclaimer Contact us Login
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Talk

Learning a new prior: Light from above

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons83906

Ernst,  MO
Research Group Multisensory Perception and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society;

Locator
There are no locators available
Fulltext (public)
There are no public fulltexts available
Supplementary Material (public)
There is no public supplementary material available
Citation

Adams, W., Graf, E., & Ernst, M. (2006). Learning a new prior: Light from above. Talk presented at 29th European Conference on Visual Perception. St. Petersburg.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-D0C1-3
Abstract
To interpret complex and ambiguous visual input, the visual system uses prior knowledge, or assumptions about the world. These 'priors' could be hard-wired, or learnt in response to statistical regularities in the environment. Here, we consider the 'light from above' prior used by the visual system to extract shape from shading. Observers viewed monocular disks with shading gradients at various orientations. Reported shape (convex or concave) as a function of stimulus orientation was used to recover each observer's assumed light position. During training, observers also 'touched' the disks. The haptic (felt) shape of the training stimuli was consistent with a light source shifted by ±1 30° from the observer's original assumed light position. After training, observers again judged the stimulus shape from purely visual information. Additionally, observers made lightness judgments of a Mach-card type stimulus, before and after haptic training with the concave/convex disk stimuli. Initially, our observers assumed a light position that was roughly overhead. However, after haptic feedback, observers learned to use a shifted light direction for their prior. Importantly, this learning was not specific to the trained task, but generalised such that it affected visual perception in a separate lightness judgment task.