so they can be tested in a meaningful
way isn’t easy, she explains. It’s hard to
say whether a cat that snags open the
kibble cabinet is displaying a cool, analytical approach to life, or whether trial
and error has simply led to success this
time around.
While psychologists describe human
behavior in five dimensions (
conscientiousness, agreeableness, neuroticism,
openness and extraversion), personality testing for nonhumans tends toward
simpler terms. Nonhuman animals can
be shy or bold, aggressive or docile, social
or asocial, and so on.
The key to distinguishing a personality amid all of a creature’s behaviors is
whether the individual responds consistently across time. A fish that hangs back
in the reeds today might be considered
shy if it does so next week and the week
after. Researchers differ in the terms
they use to describe such consistent
behavioral tendencies, using “behavioral
type,” “temperament” or “personality.”
To capture more complicated effects,
Andrew Sih of the University of California, Davis has pioneered the idea of
“behavioral syndrome,” which describes
suites of behaviors linked in different
situations, such as voracious feeding
during foraging and frequent cannibalizing of suitors during courtship.
A fishy test
Whatever terms are used for consistent
behavioral trends, mosquito fish have
them. What’s more, recent work suggests that the fortunes of any individual
loner or clinger can vary depending on
the blend in the neighborhood.
Two groups of journalist-fish, told
nothing about results from mosquito
fish studies, were persuaded to try an
exercise in mixing up types. Each put on
a mask and drew a personality profile
out of a hat. Social fish had to stay near
others as they swam along, foraging for
animal crackers and chocolate kisses
hidden among the reeflike environment
of cubicles, journal stacks and crevice-rich hallways. Loners were instructed
to dart off into more open water if two
other fish crowded nearby.
Behavioral ecologist Sean Fogarty,
who agreed to a debriefing by phone
after the event, said that some of the
office results replicated effects he sees
in his computer simulations, which are
based on real mosquito fish living in
experimental pools at UC Davis. Most
telling was a remark by fish AB/S (known
as editorial assistant Allison Bohac in
her human form), who said that as the
only social fish in a loners’ group, she
had scrounged her snacks from caches
discovered by the elusive loners she
was trying to swim with. In his computer simulations, Fogarty finds similar
behavior among social fish surrounded
by loners — in effect, a rarity bonus.
Each personality type gets some
form of bonus when it’s rare, but benefits dwindle when the type becomes
too common. If social fish are rare, just
about any individual they try to buddy
with will probably be a loner, prone to
discovering new food patches. So social
fish should grow and prosper in a largely
loner world, Fogarty says. Conversely,
a loner fish should have an advantage
when social types abound because types
that club together fail to cover maximum
ground, leaving plenty of food patches
for a loner to discover.
Had the editor-predator been permit-ted to eat a fish, the office simulation
would have shown another important
dynamic, Fogarty says. In fish-rich hallways, the victim would probably have
been one of the loners (the asocial fish
KT/L aka editor Kate Travis and RE/L
writer Rachel Ehrenberg did have close
calls). Loners don’t have the protective
cluster of buddies that can distract hungry newsroom management. In dense
populations, asocial fish face greater
risks, Fogarty says, and the size of those
risks will nudge the ultimate balance
of fish types. In the fish world, then,
socials and loners could see their local
mix affect how well they eat and whether
they are eaten.
Under what circumstances a rarity bonus will actually show up among
behavioral types in the real world is
turning out to be tricky to predict,
though. Both bold and shy barnacle
One bad strider One hyperaggressive
male water strider can spoil success for the
whole bunch. Females spend more time avoiding a group of males when one member has
this extreme trait. The avoidance means less
mating activity for the group.
Aggressivity and female avoidance
No
extreme
male
Extreme
male
0
Females in hiding
(proportion of time)
0.4 0.6 0.2 0.8
1
0.6
Mating and female avoidance
Mean group
mating activity
0.4
0.2
0
0
Females in hiding
(proportion of time)
0.4 0.6 0.2 0.8
SOURCE: A. SIH AND J.V. WATTERS/BEHAVIOUR 2005
1
geese could, in theory, nibble more food
when surrounded by their opposite type,
Ralf H. J. M. Kurvers of the Leibniz Institute of Freshwater Ecology and Inland
Fisheries in Berlin predicted before
testing real birds. He found something
else: Geese, shy or bold, found more food
when keeping bold company, Kurvers
and colleagues reported in the January-February Behavioral Ecology.
Shared fates
It’s not just the dinner of a particular
goose or fish, but the fate of the gaggle,
school or group that can change depending on the particular mix of personality
types within.
A classic demonstration of group-level
effect comes from the leggy Aquarius
