TY - JOUR
T1 - The Size-Weight Illusion is not anti-Bayesian after all
T2 - A unifying Bayesian account
AU - Peters, Megan A K
AU - Ma, Wei Ji
AU - Shams, Ladan
N1 - Funding Information:
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. MAKP was supported by the National Science Foundation Graduate Research Fellowship Program. LS was supported by National Science Foundation grant BCS-1057625. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Publisher Copyright:
© 2016 Peters et al.
PY - 2016
Y1 - 2016
N2 - When we lift two differently-sized but equally-weighted objects, we expect the larger to be heavier, but the smaller feels heavier. However, traditional Bayesian approaches with "larger is heavier" priors predict the smaller object should feel lighter; this Size-Weight Illusion (SWI) has thus been labeled "anti-Bayesian" and has stymied psychologists for generations. We propose that previous Bayesian approaches neglect the brain's inference process about density. In our Bayesian model, objects' perceived heaviness relationship is based on both their size and inferred density relationship: Observers evaluate competing, categorical hypotheses about objects' relative densities, the inference about which is then used to produce the final estimate of weight. The model can qualitatively and quantitatively reproduce the SWI and explain other researchers' findings, and also makes a novel prediction, which we confirmed. This same computational mechanism accounts for other multisensory phenomena and illusions; that the SWI follows the same process suggests that competitive-prior Bayesian inference can explain human perception across many domains.
AB - When we lift two differently-sized but equally-weighted objects, we expect the larger to be heavier, but the smaller feels heavier. However, traditional Bayesian approaches with "larger is heavier" priors predict the smaller object should feel lighter; this Size-Weight Illusion (SWI) has thus been labeled "anti-Bayesian" and has stymied psychologists for generations. We propose that previous Bayesian approaches neglect the brain's inference process about density. In our Bayesian model, objects' perceived heaviness relationship is based on both their size and inferred density relationship: Observers evaluate competing, categorical hypotheses about objects' relative densities, the inference about which is then used to produce the final estimate of weight. The model can qualitatively and quantitatively reproduce the SWI and explain other researchers' findings, and also makes a novel prediction, which we confirmed. This same computational mechanism accounts for other multisensory phenomena and illusions; that the SWI follows the same process suggests that competitive-prior Bayesian inference can explain human perception across many domains.
KW - Bayesian inference
KW - Heaviness perception
KW - Hierarchical causal inference
KW - Size-Weight Illusion
UR - http://www.scopus.com/inward/record.url?scp=84977111361&partnerID=8YFLogxK
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U2 - 10.7717/peerj.2124
DO - 10.7717/peerj.2124
M3 - Article
AN - SCOPUS:84977111361
SN - 2167-8359
VL - 2016
JO - PeerJ
JF - PeerJ
IS - 6
M1 - e2124
ER -