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Chapter 5: Learning and Cognition
5.1 Learning Allows Animals To Adapt To Their Environment
1. Learning: a relatively permanent change in behaviour as a result of experience.
LEARNING AS AN ADAPTIVE TRAIT
2. One of the simplest approaches to answer this question is to compare the
behaviour of individuals that differ in age and experience.
1. If learning improves fitness, then older more experienced individual should
outperform those that are less experienced.
3. Sullivan tested this hypothesis in a simple experiment with yellow eyes juncos,
small sparrow s that live in the mountain of southwestern North America.
1. Previous worked allowed Sullivan to age birds into four categories, recently
fledged juveniles (four to seven weeks after leaving the nest, or fledging),
young juveniles (eight to ten weeks after fledging), older juveniles (11 to 14
weeks after fledging), and adults (greater than 1 year old).
2. Juncos manoeuvre food in their bill for several seconds to prepare it for
consumption. Sullivan predicted that as birds age, they gain more
experience handling food items and so become more efficient foragers.
3. She tested this prediction by providing good that required different levels of
manipulations mealworms were cut into small pieces (0.009g dry weight_ that
were easy to handle or large pieces (0.026 g dry weight) that were more
difficult to handle. Birds had access to one food type for several days to be
sure they had some exposure to each food type.
4. Each day over the following two weeks, Sullivan recorded the handling time
of each food item (the time from first contact until the item was consumed) for
each bird. She found that for both prey types, adults had the lowest handling
time while recently fledged birds had the highest.
1. She also calculated energy gain for the foraging birds. The difference in
handling times led to differences in energy intake rate: it was highest for
adults and lowest for recently fledged birds.
1. Sullivan attributed these patterns to differences in experience. Older
birds with more experience had learned how to best handle insect prey
and this became more proficient at the task.
EVOLUTION OF LEARNING
4. Theory indicates that two factors affect the evolution of learning: environmental
stability and the usefulness of past experience.
5. Two possible types of worlds: one is fixed and nothing ever changes (i.e. no new
predators or parasites ever appear), while the other is dynamic and changes
unpredictably (e.g. new predators and parasites may appear in the middle of
the breeding season)
1. Now imagine two habitats (A and B) that differ in quality of reproduction:
breeding in one leads to high fitness, while breeding in the other leads to
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2. In the fixed world, the high-fitness habitat (A) will have always be the best
place to reproduce. In the dynamic world, the high-fitness habitat can change.
Sometimes A will be best and at other times B will be best, thanks to the
unpredictable nature of predators and parasites.
1. Let’s assume that in this changing world, each habitat has a 50% chance
each breeding season of being high quality or causing reproductive
3. In both worlds, learning would not evolve. In the fixed world, individuals that
breed in the high-fitness habitat would quickly outcompete those that
reproduce in the other habitat.
1. If habitat choice is influenced by genes, the world would soon be full of
individuals that selected only the high-fitness habitat, and there would be
no need to learn about the other habitat or the differences between them.
2. On the other hand, the dynamic world, there is nothing to learn, because
learning is useful only if the individual can benefit from their experience.
There must be a predictable relationship between experience and the best
option now available.
1. In this world, the habitats change unpredictably, and so both habitats
always have a 50% chance of being the best option, no matter what
happened in the past. Again there is not benefit of learning.
4. These factors are independent of each other but are not mutually limited. AS
environmental regularity increase, learning will become less favoured
because in a completely regular world, evolution will fix behaviour. As the
reliability of experience increases, learning will be strongly favoured because
individuals that learn will have higher fitness than those that do not.
GREEN FROG HABITUATION TO INTRUDER VOCALIZATIONS
6. Habituation: the reduction and then lack of response to a stimulus over time.
7. An environmental stimulus is anything in the environment (biotic and abiotic) that
an individual can perceive, and any reaction to the stimulus is a response.
8. Deer enemy hypothesis: territory owners will show reduced aggressive
interactions toward territorial neighbours compared to strangers.
1. The mechanism for this reduction is aggression is habituation. Strangers
represent potential threats as new competitors for territorials space, while a
neighbours represents a much lower threat, because it has already established
a nearby territory. A territory owner can save time and effort by essentially
ignoring a neighbour while aggressively interacting with strangers.
9. Owen and Perrill investigated whether the dear enemy hypothesis explains
aggression in territorial green frogs. Males defend territories around ponds,
where they vocalize to attract females. Territorial males respond to strangers with
both aggressive vocalize to attract females. Territorial males respond to strangers
with both aggressive vocalizations and physical attacks.
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1. Aggressive vocalizations can be distinguished from advertisement calls used
to attract females by their lower dominant frequency. They predicted that if
males habituate to familiar stimuli, there should be a decrease in response
to new rival’s vocalization after an initial aggressive response.
10. The researchers studied males at four ponds. They simulated intruders by
synthesizing the calls of two males and played them from a speaker placed 1 to
2m away from a focal calling male. Synthesizing the calls standardized their
length and intensity. One intruder’s dominant frequency was set at 350 Hz, while
the second intruder’s dominant frequency was set at 450 Hz.
1. For each focal calling male, the researchers first recorded advertisement.
Next, they played one of the synthetic intruder calls at 5-15 second interval
for up to an hour. During playback, the researchers recorded the focal frog’s
movement towards the speaker and it’s aggressive vocalization.
2. When the focal frogs stopped moving and began to produce advertisement
calls again the researchers stopped the playback and started 15-minute rest
period, after which they initiated the same intruder call once more.
3. The researchers again recorded the focal male’s movement toward the speaker
and aggressive calls. When movement ceased and advertisement calls were
being produced, the researchers played the second synthetic call to stimulate
a new intruder and recorded the vocalizations of the focal frog.
4. Habituation to the intruder calls was observed in both the focal frog’s
movement and vocalizations. At first, focal frogs made several movements
toward the speaker increased following the rest period and re-initiation of the
synthetic call, but at a lower level. Calling frogs produced advertisement calls
prior to the playback of the synthetic intruder but switched to aggressive calls
when the synthetic call began.
1. Eventually, focal frogs switched back to advertisement calls until a new
synthetic call was played.
5. These results suppose the deer enemy hypothesis and demonstrate habituation
to a stranger: both physical and vocal responses to the simulated intruder
were initially high but over time, both responses declined as the intruder
became more familiar and was perhaps perceived to be less of a threat.
5.2 Learning Is Associated With Neurological Changes
11. Information from experiences and environmental stimuli are perceived via
sensory receptors and relayed to the central nervous system through nerves.
Nerves are composed of neurons, cells that receive and transfer electrical and
12. The junction between two neurons, the synapse, is believed to play an important
role in learning and memory. Two aspects of the nervous system is believed to
play an important role in learning and memory: both changes in neurotransmitter
and the number of synapses between the neurons are associated with learning.
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