TOOL USING AND THE USE OF THE SCIENTIFIC METHOD
I. INTRODUCTION (examples of behavioral complexity)
A. Simple learning strongly affected by heredity:
Rats can readily associated nausea with a particular liquid or food and after one exposure will subsequently avoid that liquid or food thereafter (taste aversion learning: Garcia Effect)
B. Trial and error learning:
Bluejays form a search image of a cryptically colored moth after repeated exposure to the moth
C. Developmentally channeled learning:
White crown sparrows must hear the species-typical song in order to sing it in adulthood
Social living bank swallows can discriminate their offspring from alien young
D. Acquisition of complex motor skills
Satin bowerbirds take about 6-7 years to become proficient at building a bower
E. Mental representation, theory of mind
Chimpanzees can recognize their images in mirrors
II. TOOL USING IN BIRDS AND PRIMATES
A. What is tool use?
1. Definition -
2. Kinds of tool using:
a. extend reach
b. probe and insert
c. others
3. Tool manufacture - objects are modified to serve as tools (what are some examples?)
B. Examples of tool using in birds
1. Hungry Egyptian vultures use rocks to break the shells of ostrich eggs, and they often travel 50 yards or more to find an appropriate tool, a rock. The vulture holds the rock in its beak and drops it on the egg below. Vultures hit the egg in only about 40-60% of their throws. It is unclear how this pattern may have evolved. However, vultures may have originally thrown the eggs to break them. In that regard, vultures typically select rocks that are oval shaped like eggs.
2. Woodpecker finches not only use a tool; they also carry their tool with them. The finch uses a cactus spine inserting the spine into the tree bark with its beak and using it to stab grubs and remove them. The finch then drops the spine and grabs it with its foot while eating the grub. The finch usually carries the cactus spine to the other branches for reuse. The woodpecker finch also shows some ability to manufacture its tools in that it shortens the spines and removes bristles or knobs.
3. Herons use bait fishing to attract fish to the surface. Herons select a small stone and drop it into the water. Fish that are attracted to the stone come to the surface and are gobbled up by the heron. This pattern is relatively rare among herons.
4. New Caledonian Crow (see videoclip) - what does the crow do?
D. Example of tool using in primates
1. The two most studied species are capuchins and chimpanzees
2. Capuchins can extend reach, insert and probe, use rocks to break nuts (see video clip)
What does the capuchin do?
3. Chimpanzees can use tools to extend reach, insert and probe, and use rocks to break nuts and coconuts (see videoclip of termite fishing)
What are the two different task requirements?
E. Individual variation
There is considerable variation in tool using performance with only some members of a species using tools. Little is known about why some animals appear to use tools whereas others do not
III. TOOL USING IN RHESUS MONKEYS (use of the scientific method)
A. Objectives
1. To determine if rhesus monkeys could spontaneously use tools even though earlier studies indicated that rhesus monkeys could only use tools if they were trained to do so
2. To examine how the monkeys solved the problem (3 possible strategies)
a. trial and error - fixed solution that was not optimal and performance did not improve with time
b. ________________________________
c. Mental representation (what does this mean)
3. Comprehension: an important part of determining what animals know.
a. Using a tool does not mean that animals know what they are doing.
b. To test the hypothesis that monkeys actually comprehended their actions, monkeys were provided with modifications of the task and predictions were developed
B. Types of tasks
1. Rake Task (extending reach)
a. Monkeys were given a single rake to retrieve treats located outside their cage. They received no training. Some monkeys learned to maneuver the rake to capture treats within the rakehead and to pull the rake toward their pen.
Solution Type Number of Monkeys Nonuser Trial and Error-Fixed Trial and Error Flexible Mental Representation b. See video of monkey with a fixed strategy versus a monkey with a flexible strategy
c. To determine whether monkeys comprehended their actions:
1. Hypothesis: monkeys should understand how rakes work.
2. Different rakes were created, some of which could retreive a treat (functional) and some of which didn't work either because of position or structure (nonfunctional). Monkeys were asked to select a functional from a nonfunctional rake.
3. Prediction: monkeys should select the functional rake. Did they select the functional rake?
2. Tube Task (inserting and probing)
a. monkeys were required to insert a rod into a clear plexiglas tube mounted in the pen in order to push a treat out of the tube. No training was provided.
Solution Type Number of Monkeys Nonuser Trial and Error-Fixed Trial and Error Flexible Mental Representation b. monkeys who failed the task were given portable tubes, demonstrations, and tubes with the rod partially inserted. Did any of these manipulations have any effect?
c. The three monkeys (Ivan, Taz, and Violet) who solved the task were tested for comprehension of their actions. Did they merely learn to push a rod or did they understand more about the task?
1. Hypothesis: Monkeys comprehended the relationship between inserting a rod and getting a treat
2. Prediction: Monkeys would insert the rod only into the tube that had treats when exposed to three parallel rods only one of which had a treat
3. The parallel tube task - was the monkeys' first insertion to the correct tube?
4. Revised hypothesis: Perhaps the tubes were too close to one another that the monkeys perceived them as a single apparatus.
5. Prediction: If tubes were placed on separate walls of their pen, monkeys would insert the rod into the tube that had treats
6. Did the monkeys solve the task in this case (Yes/no) ______
What did a retest on the parallel tubes yield
for Ivan and Taz
For Violet
3. The Combo Task (Rake and Tube)
a. This task assessed whether monkeys can use two tools in sequence
a. Start with a tube task (new location and orientation). However the rod is out of reach and can only be obtained with the rake. Monkeys had to use the rake to retrieve the rod, insert the rod into the tube expelling the treat outside their cage, and then use the rake to retrieve the treat. Only the three monkeys that could solve both tasks were tested here.
Solution Type Number of Monkeys Nonuser Trial and Error-Fixed Trial and Error Flexible Mental Representation b. Why did the monkeys fall into different categories?
C. Conclusions