?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Neural+networks+as+a+model+for+visual+perception%3A+what+is+lacking%3F&rft.creator=W%C3%BCrtz%2C+Rolf+P.&rft.subject=Animal+Cognition&rft.subject=Cognitive+Psychology&rft.subject=Complexity+Theory&rft.subject=Machine+Vision&rft.subject=Neural+Nets&rft.subject=Neural+Modelling&rft.description=A+central+mystery+of+visual+perception+is+the+classical+problem+of+invariant+object+recognition%3A+Different+appearances+of+an+object+can+be+perceived+as+%60%60the+same''%2C+despite%2C+e.g.%2C+changes+in+position+or+illumination%2C+distortions%2C+or+partial+occlusion+by+other+objects.+This+article+reports+on+a+recent+email+discussion+over+the+question+whether+a+neural+network+can+learn+the+simplest+of+these+invariances%2C+i.e.+generalize+over+the+position+of+a+pattern+on+the+input+layer%2C+including+the+author's+view+on+what+%60%60learning+shift-invariance''+could+mean.+That+definition+leaves+the+problem+unsolved.+A+similar+problem+is+the+one+of+learning+to+detect+symmetries+present+in+an+input+pattern.+It+has+been+solved+by+a+standard+neural+network+requiring+some+70000+input+examples.+Both+leave+some+doubt+if+backpropagation+learning+is+a+realistic+model+for+perceptual+processes.+Abandoning+the+view+that+a+stimulus-response+system+showing+the+desired+behavior+must+be+learned+from+scratch%2C+yields+a+radically+different+solution.+Perception+can+be+seen+as+an+active+process+that+rapidly+converges+from+some+initial+state+to+an+ordered+state%2C+which+in+itself+codes+for+a+percept.+As+an+example%2C+I+will+present+a+solution+to+the+visual+correspondence+problem%2C+which+greatly+alleviates+both+problems+mentioned+above.&rft.date=1998&rft.type=Preprint&rft.type=PeerReviewed&rft.format=application%2Fpostscript&rft.identifier=http%3A%2F%2Fcogprints.org%2F507%2F2%2Frolf-cogsys98.ps&rft.identifier=++W%C3%BCrtz%2C+Rolf+P.++(1998)+Neural+networks+as+a+model+for+visual+perception%3A+what+is+lacking%3F++%5BPreprint%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F507%2F