Categorisation and concept formation

Question 1

What is concept formation?

Answer 1

The induction of concepts that divides items into classes according to their shaped properties

Concepts are not always defined by specific features, sometimes do not have necessary or sufficient features

Question 2

What did Bhatt et al (1988) say about basic level concept formation in animals?

Answer 2

• Pigeons in a chamber with choice of four response keys
• Shown pictures of flowers, cars, people and chairs
• Birds learned to peck different keys for exemplars of each of four categories of pictures
• Then tested with new exemplars, they had never seen before
• They were also able to respond correctly to the new exemplars

Suggests birds had formed ‘concept’ of flowers, cars, people and chairs

Performance more accurate with the training stimuli (80%) than with the novel, test stimuli (60%)

Question 3

What is the exemplar theory?

Answer 3

Learn about every instance independently, classify novel exemplars via similarity to learned instances

• predicts classifying a novel item always worse than one you have seen before

Question 4

What is the prototype theory?

Answer 4

Learn about abstract prototype, corresponding to central tendency of training exemplars

• predicts classifying a novel item can be better than one you have seen before, it may be the prototype you stored

Classify novel exemplars on basis of similarity to prototype you have never seen

Question 5

What are the predictions of the two theories?

Answer 5

In that experiment, birds clearly stored information about training exemplars - were more accurate with them than the novel test stimuli

Their performance could be explained by exemplar theory

However, humans can show the prototype effect – categorize prototype more accurately than the training stimuli - even though it has never been seen before

Question 6

What did Aydin and Pearce (1994) study on prototype effect in pigeons?

Answer 6

1. Create a prototype
2. Artificial positive and negative prototypes defined as ABC and DEF
3. The birds trained on 3 element displays, created by distorting the prototypes

Birds taught three positive patterns always paired with food, the three negative patterns were not

Birds pecked more at positive than negative patterns

Tested training patterns and the prototypes, test of prototype theory is whether they are more accurate with prototype they never experienced

Birds responded more to positive prototype ABC than to positive patterns, and less to negative prototype, DEF, than to any negative patterns

Question 7

What did Whittlesea (1987) study about exemplar effect in humans?

Answer 7

Lists 1, 2 and 3 all differ from prototype by 2 letters equally similar to prototype
Examples in list 1 more similar to list 2 than 3

If they learned prototype, lists are equally similar to prototype, should be equally good at categorising all lists

Pretest with all stimuli: 30ms presentation followed by a mask, then has to write down as many letters as they could
Score is improvement from pretest

List 1 was easier than list 2, which was easier than list 3
Humans show results consistency with exemplar theory

Question 8

Which theory is correct?

Answer 8

Both humans and animals retain information about the training items/exemplars (consistent with exemplar theory)

But show the prototype effect (consistent with prototype theory)

It turns out that a variation of exemplar theory can explain the prototype effect!

The two theories not so different

Question 9

What did Aydin and Pearce (1994) study?

Answer 9

Examine learning about each component feature of the positive trained exemplar

Components of training exemplar appear on 5 food and 4 no food trials

Components of prototype appear on 6 food and 3 no food trials - more than training exemplar

Question 10

What is the feature theory?

Answer 10

They both say you store something about stimuli on each trial
Learn about/store component features of each exemplar

New stimuli classified on basis of sharing features with stored exemplars

Question 11

What is blocking of categorisation according to Shanks (1990)?

Answer 11

Subjects given trials in which medial symptoms paired with a disease diagnosis

Subjects must predict disease from symptom

Headache paired with flu, runny nose is also present and when headache paired with NA, rash is also present and runny nose predicts flu much better than rash predicts

So flu is less surprising when paired with headache than NA is when paired with headache - poorer learning about flu

Question 12

What do the theories predict about blocking of categorisation?

Answer 12

Nonassociative account predicts that, given headache, subjects will be just as likely to predict flu as NA

Associative theory predicts that, given headache, subjects will be more likely to choose rare NA than common flu

Ppts more likely to predict that a headache will produce NA

Associative learning is best explanation of performance on this categorisation task in human subjects

Question 13

What are superordinate categories?

Answer 13

Have members that are not necessarily physically similar to each other, but share a common associate

Question 14

How did Wasserman et al (1992) say about superordinate level concept formation?

Answer 14

• Pigeons trained with slides of people, chairs, cars and flowers
• Reinforced for making Response 1 to either people or chairs, and for making Response 2 to either cars and flowers
• People and chairs in one category, cars and flowers in another
• Then made Response 3 to people, and Response 4 to cars tested chairs and flowers, with choice of Response 3 & Response 4

Question 15

How is superordinate level concept formation presented in animals?

Answer 15

Birds formed superordinate category

Treat people and chairs as equivalent because both paired with the same response in the first phase

A more complex type of categorization because category members not physically similar

Some say this is not true categorization, just simple “associative learning” - and that what humans do is somehow more complicated

Question 16

What is abstract concept formation in animals?

Answer 16

Relatively little done on abstract concepts in animals

The one that has been studied most is same/different, usually studied using a match-to-sample technique (MTS)

Birds shown a sample key, then given a choice of red and green

Must peck the same colour as the sample

Question 17

How do more complex training techniques seem to produce better results?

Answer 17

• Pigeons shown complex stimulus displays, and given a choice of a red and a green key
• They were trained on arrays with one set of specific icons
• Rewarded for pecking red on same trials, green on different trials
• Finally they were tested with different arrays involving different specific icons

Question 18

What are the conclusions of abstract concept formation?

Answer 18

• Animals can form basic, superordinate, and to a limited extent abstract concepts

Three theories of basic level concept formation:

• Exemplar, prototype and feature theory
• Debate as to which is best
• May involve associative learning