  Humans effortlessly infer the 3D shape of objects. What computations underlie
this ability? Although various computational models have been proposed, none of
them capture the human ability to match object shape across viewpoints. Here,
we ask whether and how this gap might be closed. We begin with a relatively
novel class of computational models, 3D neural fields, which encapsulate the
basic principles of classic analysis-by-synthesis in a deep neural network
(DNN). First, we find that a 3D Light Field Network (3D-LFN) supports 3D
matching judgments well aligned to humans for within-category comparisons,
adversarially-defined comparisons that accentuate the 3D failure cases of
standard DNN models, and adversarially-defined comparisons for algorithmically
generated shapes with no category structure. We then investigate the source of
the 3D-LFN's ability to achieve human-aligned performance through a series of
computational experiments. Exposure to multiple viewpoints of objects during
training and a multi-view learning objective are the primary factors behind
model-human alignment; even conventional DNN architectures come much closer to
human behavior when trained with multi-view objectives. Finally, we find that
while the models trained with multi-view learning objectives are able to
partially generalize to new object categories, they fall short of human
alignment. This work provides a foundation for understanding human shape
inferences within neurally mappable computational architectures.
