PSY352H5 Lecture Notes - Lecture 8: Classical Conditioning, Reinforcement, Operant Conditioning
Friday, March 14, 2014
Lecture 8
WHAT IS FORAGING?
-Foraging is looking for and consumption of food, the search for food and its
consumptions is universal to all animals
-The specific principles of foraging are common to all animal species, even if the
actual behaviours exhibited may be very diverse
-What can foraging tell us about animals?
•Foraging behaviour can describe the relationship between species, these
relationships can be simple and involve two species (ex. panda eats only bamboo
leafs) or these relationships can involve the complicated web if predators and prey
(ex. squirrels, rabbits, mice eat grass but they are being food for another predators
such as fox, hawks and owls..)
-Foraging behaviour has a range of motivations:
•Hunger is considered the primary motivation for foraging but is not the only factor
that can stimulate foraging
•Social cues such as lunch time, friends eating, food around, conditioning
•MOTIVATIONS= learning what to eat, learning can shape foraging behaviour,
solitary animals can learn where to forage and what to eat. Associations made by
classical conditioning by pairing neutral stimulus with the conditioned stimulus and
conditioned response. Once you are conditioned to like some food, you can start
salivate as a intuitive response, without any conscious effort (Pavlov’s experiment).
-octopus: you can use animal’s ability of foraging to teach them something, so this
octopus learned how to open jar when there was food inside by operant
conditioning, so they opened the jar and the positive reinforcer - food was
gained, so they learned how to open even more hardly closed jar
-rats demonstrate neophobia -> aversion to new food, if you show them
something new they will avoid it for a great amount of time, maybe start trying to
eat slowly slowly and if there is no problem they eat it, if there is problem they
just avoid it which protects them from poisoning -> this has evolutionary value in
terms of survival and protection from novel food that can make them poison
1
Friday, March 14, 2014
-CONDITIONED TASTE AVERSION (CTA): it is a form of classical conditioning, in
classical conditioning an unconditioned stimulus (USC) is paired with a
conditioned stimulus (CS) to produce an conditioned response (CR)
•UCS produces an unconditioned response (UCR)
•CS + UCS = UCR eventually
•CS=CR
•CTA: food (UCS) laced with an sickness inducing agent (CS) causes animal to
associate the food with the sickness
•this type of conditioning requires very little exposure and most times just one
bad experience is enough to condition the animal -> this form of conditioning is
also very resistant to extinction (animals and humans do not forget it easily)
-Animals exploit information provided by neighbours
•Information transfer hypothesis - one individual gains insight/information from the
actions/cues provided by another and then acts upon the information for its own
benefits: example of ospreys: there were four fish A,B,C, and D. Fish A does not
form a group and stays by herself, on the other hand fish B,C and D live in groups.
When birds eat fish from group A, they do not tend to come back to the same fish
because they are not living in groups so they better go back to group B,C and D
because they can get more fish from there. Birds can transfer this information
between each others and it is called information transfer hypothesis.
-Group membership has both benefits and disadvantages. Group membership can
increase an individual’s foraging success
•because, being part of a group may afford some degree of protection (if you are by
yourself you need to be eating and watching of you are save)
•working with a group may be more advantageous for the individual than working
alone - it has been shown that flock size increase the individual success of gulls
•once the balance between number of species in the group is reached, the natural
selection will choose the best possible behaviour for next generations
•cooperation benefits all!!!
-herbivores do not need capture prey thus increased ease of prey capture cannot
explain the formation of foraging groups of herbivores
2
Friday, March 14, 2014
-bret geese - feed on saltmarsh that have maximum nutrition after 4 days of
growth after cropping, synchronized feeding insures that all Brent geese eat
-active cooperation enhances foraging success -> working together increases
hunting success for lions, wolves, killer whales, humans and others
-What can foraging tell us about animals? How animals decide what to eat? Quantity
vs. Quality - some animals prefer quantity and others prefer quality. It works for
ecosystem that animals have different preferences because then there is less conflict
of for food resources
•Quantity: trigger fish and butterfly fish may consume between 50 to 100% of alga
production a reef system, seaweed is relatively poor in nutrients, this in order to
maximized energy intake each fish needs to consume large amounts of material,
thus these fish maximize nutrient intake by increasing quantity
•Quality: green turtles primarily graze on sea grass Thalassia testudinum, which has
a constant nutrient quality, but the more mature plants are high in cellulose which is
hard to digest even for green turtles. However, young shoots are low in cellulose
and are high in protein, green turtles return to same areas and crop over and over
again
-Deciding what to eat: does not only depends on the quality vs. quantity preferences
BUT also those dietary preferences may depend upon age or developmental stage of
an individual (subtidal feeding vs. intertidal feeding)
•Experimental support: in 1986 Trillmich and Trillmich studied the foraging patterns
of marine iguanas of the galapagos islands: These researchers noticed that there
were two foraging strategies:
-subtidal feedings: swimming out to sea to the subtidal areas which is dominated
by a large diversity of plants
-intertidal feeding: feeding around the low tide in the intertidal zone, which is
covered in water during high tide and exposed during low tide
-they found that sub tidal feeders were larger members weighing more than 1.8
kg, while intertidal feeders were smaller members weighing less than 1.2 kg ->
iguanas that used both strategies were between 1.2 and 1.8 kg
-explanation: subtidal foraging is independent of weather patterns and tides,
Intertidal feeders have to match their foraging to the tides, they may have
insufficient time to warm up before foraging the morning and after foraging at
3
Document Summary
Foraging is looking for and consumption of food, the search for food and its consumptions is universal to all animals. The speci c principles of foraging are common to all animal species, even if the actual behaviours exhibited may be very diverse. Associations made by classical conditioning by pairing neutral stimulus with the conditioned stimulus and conditioned response. Once you are conditioned to like some food, you can start salivate as a intuitive response, without any conscious effort (pavlov"s experiment). Birds can transfer this information between each others and it is called information transfer hypothesis. Group membership has both bene ts and disadvantages. Herbivores do not need capture prey thus increased ease of prey capture cannot explain the formation of foraging groups of herbivores. Bret geese - feed on saltmarsh that have maximum nutrition after 4 days of growth after cropping, synchronized feeding insures that all brent geese eat.
