D
o you remember Dory, the well-meaning
surgeonish with the 1-minute memory in the
ilmFinding Nemo? Although the ilm
portraits her as unusual, in many ways she plays
to the common conception that ish only have
a very limited memory. Onejoke even concludes that there’s no
need to worry about the ish tank becoming boring because
every time the ish turn around they think: “Oh, that’s nice,
haven’t seen that before!”
But like a lot of our preconceptions, there’s precious little
evidence to support this notion. Indeed, goldish have been
tested on some tasks and can recall them months and even years
later.
In fact, work in our lab has revealed that some species of reef
ish can recognise faces belonging to other individuals of their
own and other species. How is this possible in an animal with
a 3-second memory and a very small brain?
Our indings challenge assumptions about the limited capa-
bilities of the ish brain. Beyond that, they are informing us
about what is, and what is not, special about the human cere-
bral cortex.
So why our special interest in face recognition? Many neuro-
scientists argue that the human brain possesses innate, specialised
face discrimination circuits that are central to basic face recog-
nition tasks. The task is complicated by the presence of other
very similar-looking objects – other faces – and made even
harder by changes in hair, clothes, facial expression and viewing
direction. Our capacity to do this is effectively at the limit of our
visual abilities. A bank robber or a superhero only needs to wear
an eye mask to obscure their identity.
How do humans do it? What features are they using? How
can they recognise a face when a person turns their head or
walks into a room with different illumination?
One clue lies in the ish we have been studying. If, as we have
shown, ish can tell individual faces apart as easily as they can
tell other objects apart, it appears that some aspects of face
recognition do not require specialised cortical circuitry after
all. These indings are motivating us to delve deeper into theJUNE 2016|| 15Recognising Nemo
ULRIKE SIEBECK & GUY WALLIS
Recent studies are helping to dispel the myth that fish have a 3-second memory. In fact, some
species of reef fish can even recognise human faces.
Stephen Coburn/adobe