Biology Reference
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by a dominant bird, than when they were observed by their partner or by a subordinate
bird. There is also an intriguing hint that birds that have pilfered themselves are more
likely to move their caches when they have been observed, a case of 'it takes a thief to
know a thief ' (Emery & Clayton, 2001).
The third aspect of animal intelligence investigated in scrub jays is sometimes dubbed
'mental time travel', the ability to project into the future, independently of current
physiological requirements, and plan appropriately, just as humans do when they make
a weekly shopping list and head off to the supermarket even when they are not hungry.
Experiments aimed at demonstrating this ability have to carefully control for other
explanations, such as learning through repeated exposure to a sequence of events, or
timing linked to the body's internal clock.
Raby et al . (2007) demonstrated behaviour in food storing scrub jays that could be
interpreted as mental time travel. The birds lived in a set up with three compartments: a
central area and a 'room' at either end. During a training phase, the birds were locked
in one of the two end rooms overnight. In one room they were provided with food as
soon as the lights came on in the morning, whilst in the other room, there was a delay
of two hours before food was offered. After this training, the birds were allowed to store
pine nuts placed in a bowl in the central compartment, and they preferred to hide the
food in the room where they were not fed first thing in the morning. They did this on the
first occasion they were allowed to store food, suggesting that they could project forward
and anticipate in which room they would be hungry if locked in overnight. In a second
experiment, birds were trained to experience breakfast in both rooms, but in one room
the meal was always pine nuts and in the other it was always dog food. When given a
choice of food to store, the birds hid pine nuts in the dog food room and dog food in the
pine nuts room, as though anticipating the kind of food they would get for breakfast,
and making their diet more varied by storing the opposite kind of food.
These studies show that food storing birds have surprising mental abilities that extend
beyond spatial memory, but are they specialized adaptations that have arisen during
evolution in association with food storing behaviour? At the moment we cannot say
without a comparison of storing and non-storing species, such as those on spatial
memory of corvids that were described earlier. The study of food storing birds does,
however, provide a remarkable example of inter-relationship between ecology, behaviour
and the brain.
The food storers also raise a more general question about 'animal intelligence'. Sarah
Shettleworth (2010a, 2010b) asks whether the results from food storing birds, and
other similar examples, could be the result of simple processes, such as associative
learning, or whether they imply that non-human animals have more complex cognition
involving a 'theory of mind', namely treating others as intentional beings, attributing
to them knowledge, belief, desires and other intentional states.
Shettleworth makes three important points. Firstly, apparently complex behaviours
can be generated by very simple behaviour mechanisms: these are what Daniel Dennett
(1983) has called 'killjoy' explanations. A famous example of this is the demonstration
that pigeons, with appropriate pre-training, could solve a novel problem that involved
moving a box to the correct place and then climbing onto it get to a reward that was
otherwise out of reach (Epstein et al ., 1984). This experiment mimicked a classic report
by Wolfgang Kohler (1929) who concluded that similar behaviour by chimpanzees
showed that they had 'insight' (the 'aha' experience of suddenly figuring out the
Mental time
travel: planning
for the future
Intelligence and
simple rules
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