Data from: Do goldfish like to be informed?

Like humans, several mammalian and avian species prefer foretold over
unsignalled future events, even if the information is costly and confers
no direct benefit. It is unclear whether this is an epiphenomenon of basic
associative learning mechanisms or whether these preferences reflect a
derived form of information-seeking that is reminiscent of human
curiosity. We investigate whether a fish that shares basic reinforcement
learning mechanisms with birds and mammals, also shows such a preference,
with the aim of elucidating whether widely shared conditioning processes
are sufficient to explain paradoxical preferences resulting in unusable
information. Goldfish (Carassius auratus) chose between two alternatives,
both resulting in a 5s delay and 50% reward chance. The ‘informative’
option immediately produced a stimulus correlated with the trial’s
forthcoming outcome (reward/no reward). Choosing the ‘non-informative’
option instead triggered an uncorrelated stimulus. Goldfish discriminated
between the different contingencies, but did not develop a preference for
the informative option, suggesting that in goldfish, associative learning
mechanisms are not sufficient to generate preferences between alternatives
differing only in outcome predictability. These results challenge the
notion that informative preferences are a by-product of ubiquitous
associative processes, and are consistent with the possibility that
derived information-seeking mechanisms have evolved in some vertebrate
species.