Chapter 11Tool use in animals

Cognitive Ethology

Examines cognitive processing in animals

What is cognition?The ability to relate different unconnected pieces of

information in new ways, and apply the resulting knowledge in an adaptive manner

While no one doubts cognition in humans, the question of cognition in animals is quite controversial

How could animals learn how to solve new problems?

Stimulus-response learning: making simple associations between a stimulus and a response

Explicit learning: learning explicit representations of facts that are accessible to many different processes

Procedural learning: learning how to execute a particular procedure. This knowledge does not generalize to different procedures

This rat has a mental imageof its goal, and moves through the

maze seeking that goal; it canapply this knowledge to a variety of

different mazes or situations

Explicitknowledge

Proceduralknowledge

This rat has learned how toperform in the maze, and movesthrough the maze automatically

(i.e., without a specific goal)

Definition of Tool Use“the use of an external object as a functional extension of

mouth or beak, hand or claw, in the attainment of animmediate goal” (van Lawick-Goodall, 1970)

Examples of Tool Use in AnimalsUsing toolsSea otters break mollusk shells on stone “anvils” that they hold on their chestEgyptian vultures throw stones at ostrich eggs to crack themChimpanzees use bunches of leaves as sponges to collect water from crevices

Making and using toolsCaptive blue jays have been observed tearing strips of paper and using them to pull

in food through the bars of their cagesChimpanzees make a variety of tools from sticks, leaves and grassSee example with New Caledonian crows on next page

Bending wire into hooks by a captive Caledonian crow

The female New Caledonian crow is extracting a bucket containing

meat using a piece of wire that she just bent.

Outline tracings of all the bent wires, with the end inserted into the tube facing right. Numbers refer to the trial number. The wire bent in trial 8 was not successfully used to

retrieve the bucket.SEE MOVIE

In 1925, Wolfgang Kohler examined “insight learning” in captivechimpanzees. He was one of the first cognitive ethologists.

A chimpanzee using a stick, which was left in the cage, to obtain an apple

A chimp standing on boxes to obtainfruit suspended from above.

Note that the boxes it is standing on, and the stick it is reaching with, had been strewn randomly in the cage.

Is the chimp using explicit or procedural knowledge?

Chimpanzee modifyingthe tip of a stick beforeexhibiting the “termite

fishing” behavior

What type ofknowledge it the

chimpanzee usingto perform this

behavior accurately?

One troop of chimpanzees lives in an area of the Congo with abundantcoula nuts. The shell of these nuts is extremely hard, and can

be opened only with the help of heavy stones. The nut crackingbehavior consists of the following components:

1. Chimp ranges over large distances in search of appropriate stones orsticks

2. Chimp collects large number of nuts3. Chimp collects small probes4. Chimp assembles collected items in one area and sits down5. Chimp places a nut on top of one stone and then crushes it by striking it

from above with another stone6. Chimp scoops out fruit or nut7. Chimp cracks another nut…

Note the infant observingits mother exhibit the nut

cracking behavior

Photograph of femalechimpanzee cracking

a coula nut, withher infant watching

from behind

There are severalobservations of

mothers correcting theiryoung as they attempt

to learn the behavior

Comparison of tool-use in a great ape and new world monkey

Prosimians

Greatapes Old World

monkeys New Worldmonkeys

! !

Problem 1: The tube task

The monkey must learn to insert the stick into the tube, from either end, to push out the candy

A capuchin monkey is attentively observing a cage-mate solving the tube task

All of the capuchin monkeys and the chimpanzees learned the tube test relatively quickly and easily

Trap-tube test

To obtain the candy, there is only one way to insert the stick

While watching the candy, Roberta inserts the stick into the wrong side of the tube

Note that a candy, lost in a previous trial, is already inside the trap

Results of sequential blocks of tests with 4 different capuchin monkeys:

Only 1 monkey solved the trap-tube test (Rb)

Results of sequential blocks of testingwith 5 different chimpanzees:

Only 2 chimps solved the trap-tube task (Darrell and Sheba)

How did the 1 capuchin monkeyand 2 chimpanzees solve the trap-tube task?

Did they use a type of procedural knowledge?

Or, did they use a type of explicit knowledge?

If they used explicit knowledge, then how would you expect them to perform in the trap-tube test with configurations A and B?

A

B

So, what type of knowledge about the trap-tube task does eachtype of primate have?

The 2 chimps selectively inserted the stick into the left side withconfiguration B, but not with configuration A

A

B

The capuchin monkey selectively inserted the stick into the left sidewith configurations A and B

How did the capuchin monkey solve the trap-tube test?