?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Class+Similarity+and+Viewpoint+Invariance+in+the+Recognition+of+3D+Objects&rft.creator=Edelman%2C+Shimon&rft.subject=Cognitive+Psychology&rft.description=In+human+vision%2C+the+processes+and+the+representations+involved+in+identifying+specific+individuals+are+frequently+assumed+to+be+different+from+those+used+for+basic-level+classification%2C+because+classification+is+largely+viewpoint-invariant%2C+but+identification+is+not.+This+assumption+was+tested+in+psychophysical+experiments%2C+in+which+objective+similarity+between+stimuli+(and%2C+consequently%2C+the+level+of+their+distinction)+varied+in+a+controlled+fashion.+Subjects+were+trained+to+discriminate+between+two+classes+of+computer+generated+3D+objects%2C+one+resembling+monkeys%2C+and+the+other+dogs.+Both+classes+were+defined+by+the+same+set+of+56+parameters%2C+which+encoded+sizes%2C+shapes%2C+and+placement+of+the+limbs%2C+the+ears%2C+the+snout%2C+etc.+Interpolation+between+parameter+vectors+of+the+class+prototypes+yielded+shapes+that+changed+smoothly+between+monkey+and+dog.+Within-class+variation+was+induced+in+each+trial+by+randomly+perturbing+all+the+parameters.+After+the+subjects+reached+90%25+correct+performance+on+a+fixed+canonical+view+of+each+object%2C+discrimination+performance+was+tested+for+novel+views+that+differed+by+up+to+60+deg+from+the+training+view.+In+experiment+1+(in+which+the+distribution+of+parameters+in+each+class+was+unimodal)+and+in+experiment+2+(bimodal+classes)%2C+the+stimuli+differed+only+parametrically+and+consisted+of+the+same+geons+(parts)%2C+yet+were+recognized+virtually+independently+of+viewpoint+in+the+low-similarity+condition.+In+experiment+3%2C+the+prototypes+differed+in+their+arrangement+of+geons%2C+yet+the+subjects'+performance+depended+significantly+on+viewpoint+in+the+high-similarity+condition.+In+all+three+experiments%2C+higher+inter-stimulus+similarity+was+associated+with+an+increase+in+the+mean+error+rate+and%2C+for+misorientation+of+up+to+45+deg%2C+with+an+increase+in+the+degree+of+viewpoint+dependence.+These+results+suggest+that+a+geon-level+difference+between+stimuli+is+neither+strictly+necessary+nor+always+sufficient+for+viewpoint-invariant+performance.+Thus%2C+basic+and+subordinate-level+processes+in+visual+recognition+may+be+more+closely+related+than+previously+thought.&rft.date=1995&rft.type=Preprint&rft.type=NonPeerReviewed&rft.format=application%2Fpostscript&rft.identifier=http%3A%2F%2Fcogprints.org%2F577%2F2%2F199711011.ps&rft.identifier=++Edelman%2C+Shimon++(1995)+Class+Similarity+and+Viewpoint+Invariance+in+the+Recognition+of+3D+Objects.++%5BPreprint%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F577%2F