Lecture 23: Animal Cognition II (Special Topics)

Learning, Psychology 5310

Spring, 2015

Professor Delamater

Selected Special Topics in the Study of Comparative Cognition

1. Episodic memory in non-human animals2. Interval Timing3. Serial Order learning4. Categorization and Concept Learning

Episodic Memory: Food Caching Birds

1. Kamil and Balda (1985) study2. Clayton and Dickinson (1999) study

• Clark’s nutcrackers live in Alpine regions of the western US.• They are known for their uncanny ability to retrieve cached

food in the wild. They store seeds from pine cones during the summer and fall, and then retrieve them in the winter and spring.

• They can store up to 33,000 seeds and recover several thousand of them at some later time.

• Can they do this because they remember well, or because they can spot markings of where they’ve been? Or just randomly run into food they’ve or others have previously stored?

Kamil and Balda (1985) study

Episodic Memory: Food Caching Birds

1. Kamil and Balda (1985) study2. Clayton and Dickinson (1999) study

• Kamil and Balda forced the birds to store up to 18 seeds in a laboratory environment with 225 storage holes. However, only 18 were available at any given time.

• Then, after some delay period, they were allowed to retrieve their stored caches.• But, during this retrieval test, all 225 storage holes were accessible.• The birds could recover their caches 2-4 times greater than would be expected by

chance.• Furthermore, they could remember these after as long as a 285 day delay.

Episodic Memory: Food Caching Birds

1. Kamil and Balda (1985) study – This study shows an amazing memory ability.2. Clayton and Dickinson (1999) study – This study shows some evidence for episodic

memory in birds (Scrub Jays).

What is “episodic” memory? Is it uniquely human?a. Usual answer is that it is a recollection of a particular event that took place

in a particular location at a particular time. In essence, you reexperience theepisode.

b. Aside from the conscious aspects of this memory, it can be characterizedAs a memory containing “what,” “where,” and “when” information.

c. Clayton and Dickinson (1999) asked if scrub jays had this kind of memory.

Episodic Memory: Food Caching BirdsClayton and Dickinson (1999) study

• Birds were asked to cache different types of food (peanuts and mealworms) into icecube trays that had sand in them and were surrounded by lego block structures.

• Then they were asked to retrieve them after 4 or 124 hour delays.• Some birds learned, though, that the meal worms deteriorated after 124 hours,

whereas for others the bad mealworms were replenished with fresh ones.

Episodic Memory: Food Caching BirdsClayton and Dickinson (1999) study

• Since the jays preferred mealworms to peanuts, the Replenish group always retrievedmore mealworms (W) than peanuts (P) during the 4 and 124 hour tests.

• The birds that learned that mealworms decay after 124 hours preferred the peanuts tothe mealworms after 124 hours, but worms to peanuts after 4 hours.

• This means that the birds knew after 124 hours what food was stored where and whenit was stored there.

• This suggests that the scrub jays, like humans, may have episodic memories.

Interval Timing: Methods & Properties

1. Duration Estimation (symbolic matching to sample task….)

• In the duration estimation task, the subject judges whether the first stimulus (the sample stimulus) is short or long.

• If it is short, then choosing the left response is reinforced with food, but if it is long, then choosing the right response is reinforced with food.

Tone

Tone

Choose Response 1 if shortChoose Response 2 if long

Sample Stimulus Choice

Interval Timing: Methods & Properties

1. Duration Estimation (symbolic matching to sample task….)2. Peak Procedure (duration production)

• In the peak procedure, a stimulus comes on and signals reward opportunity after a fixed interval (e.g., FI 20 s).

• But on nonreinforced probe trials, the duration of the trial is extended and no reward can be earned.

• It is on these trials that we assess responding as a function of time.

ResponseS

Training trialsFixed Interval 20 s

S

Nonreinforced Probe trials80-s S duration

RewardResponse

Interval Timing: Methods & Properties

1. Duration Estimation (symbolic matching to sample task….)2. Peak Procedure (duration production)

• In this case one discriminative stimulus signaled FI 20 reward, while a second signaled FI 40.

• The rats lever press rate on probe trials peaked at 20 and 40 s, respectively, in the presence of the two stimuli.

• This indicates that they have learned about reward time.

• Also, not that the variability (spread) of the two timing functions differ.

• The amount of variation increases with the mean of the interval being estimated.

Roberts (1981) study

• In fact, responding is related to the proportion of time elapsed, independent of the value of the interval being judged. This is known as the scalar invariance property of interval timing.

Interval Timing: Theories1. Scalar Expectancy Theory (Gibbon & Church, 1984)2. Behavioral Theory of Time (Killeen & Fetterman, 1993)3. Multiple Oscillator Theory (Church & Broadbent, 1990)

• There are clock, memory, and decision processes in the scalar expectancy model.

• Clock generates counts in an accumulator.

• Memory: Running count vs reinforced memory count (at time of reward).

• Decision: Compares running value of elapsed time in working memory to the stored reinforced time in reference memory.

• Comparator rule shows how behavior will be proportionally related to the value of the reinforced time in reference memory.

Gibbon and Church, 1984

Comparator:(N* - N) < b (threshold) N*

Interval Timing: Theories1. Scalar Expectancy Theory (Gibbon & Church, 1984)2. Behavioral Theory of Time (Killeen & Fetterman, 1993)3. Multiple Oscillator Theory (Church & Broadbent, 1990)

• In the Multiple Oscillator theory, there are different oscillators that run concurrently.

• Each oscillator has a different periodicity.

• Each moment in time has a different pattern of activation across the different oscillators.

• These different patterns of activation are thought to code different temporal intervals.

Church and Broadbent, 1990

Time 1 Time 2

Serial Order Learning1. Learn a sequence of responses: 123 234 345 456 567 678 (Fountain, et al, 2012)2. Do the rats learn an internal representation of the sequence or do they learn

a chain of S-R associations?

• They learn a structured sequence better than a non-structured one.• But that could be understood in terms of easier associative learning….

Serial Order Learning1. Learn a sequence of responses: 123 234 345 456 567 678 (Fountain, et al, 2012)2. Do the rats learn an internal representation of the sequence or do they learn

a chain of S-R associations?3. Terrace, Son, and Brannon (2003) study

• Monkeys first learned 4, 7-item sequences:A1 – A2 – A3 – A4 – A5 – A6 – A7B1 – B2 – B3 – B4 – B5 – B6 – B7C1 – C2 – C3 – C4 – C5 – C6 – C7D1 – D2 – D3 – D4 – D5 – D6 – D7

• These stimuli were different pictures taken from several different categories.• Then the monkeys were given a set of 2-item probe tests consisting of different

stimuli from the different sets. They asked whether the monkeys couldaccurately select the first item.A3 – C5, B2 – D4, C5 – D7, D3 – A4, etc

• The monkeys DID choose the “earlier” item of each sequence even though theseparticular items were never trained together.

• It looks like the monkeys had constructed a representation of the order of each sequence, and this order guided their choices, not a series of S-R associations.

Categorization & Concept Learning1. Classic Herrnstein, Loveland, and Cable (1976) study

• Pigeons learn to categorize pictures of people vs plants.• A control group is trained to arbitrarily categorize different sets of stimuli.• The individual stimuli chosen for this study are taken from a large number of items

(somewhere on the order of 100 or more).• Then, during a test phase the animals are tested with NEW exemplars (ones they

never saw before), and were asked to choose to respond.• The birds learning the Categorization task did so fairly well, with some loss in

accuracy.• Later work has shown that greater generalization occurs in these tests as the

number of exemplars in the training set increases.

Categorization & Concept Learning1. Grainger, et al (2012) study with baboons

• Baboons first learned to categorize English words vs non-words (up to over 300 exemplars of each)

• Then they were tested with new words and non-words they hadnt seen before.

• They’re performance was pretty good, as can be seen on the graph to the right.

Categorization & Concept Learning: Mechanisms of Concept Learning

1. Aust and Huber (2003) study with pigeons

• The birds first learned to classify picturesof people vs no people

• Then they were tested with new exemplarsof people that were in their originalform or were rearranged in variousways.

• The birds responded most when the newpeople were in their original form, butthey responded more to rearrangedpeople than to slides with no people in them.

• This suggests that the birds responded at least partly on the basis of the specific features making up the original slides.

• This is the Feature Theory of Concept learning.• Notice how this is rather similar to the Rescorla-Wagner theory of simple

conditioning.

Categorization & Concept Learning: Mechanisms of Concept Learning

2. Wright and Katz (2007) study with pigeons, rhesus monkeys, capuchin monkeys

• This was a Same/Different concept learning task• Do these species learn “abstract” concepts?• If the two objects on a trial are the same, then

touching the lower picture is correct.• If the two objects are different, then touching the

button to the right of the lower picture iscorrect.

• After the basic learning phase, then the animalsare given tests with new exemplars.

• The basic findings are that generalization to new exemplars increases as the number of training exemplars increases.

• This result occurs in all species suggesting that all species may learn in similar ways.

• Perhaps they are abstracting some general notion of sameness, and responding on the basis of this representation. Further work is needed to clarify the nature of that representation.