Understanding the neural code is
critical to linking brain and behavior. In sensory systems, divisive
normalization seems to be a canonical neural computation, observed in
areas ranging from retina to cortex and mediating processes including
contrast adaptation, surround suppression, visual attention, and
multisensory integration. Recent electrophysiological studies have
extended these insights beyond the sensory domain, demonstrating an
analogous algorithm for the value signals that guide decision making,
but the effects of normalization on choice behavior are unknown. Here,
we show that choice models using normalization generate significant
(and classically irrational) choice phenomena driven by either the
value or number of alternative options. In value-guided choice
experiments, both monkey and human choosers show novel
context-dependent behavior consistent with normalization. These
findings suggest that the neural mechanism of value coding critically
influences stochastic choice behavior and provide a generalizable
quantitative framework for examining context effects in decision making.
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