The
notion of subjective value is central to choice theories in ecology,
economics, and psychology, serving as an integrated decision variable
by which options are compared. Subjective value is often assumed to be
an absolute quantity, determined in a static manner by the properties
of an individual option. Recent neurobiological studies, however, have
shown that neural value coding dynamically adapts to the statistics of
the recent reward environment, introducing an intrinsic temporal
context dependence into the neural representation of value. Whether
valuation exhibits this kind of dynamic adaptation at the behavioral
level is unknown. Here, we show that the valuation process in human
subjects adapts to the history of previous values, with current
valuations varying inversely with the average value of recently
observed items. The dynamics of this adaptive valuation are captured by
divisive normalization, linking these temporal context effects to
spatial context effects in decision making as well as spatial and
temporal context effects in perception. These findings suggest that
adaptation is a universal feature of neural information processing and
offer a unifying explanation for contextual phenomena in fields ranging
from visual psychophysics to economic choice.
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