Categorisation and concept formation

Question 1

what is concept formation?

Answer 1

the induction of concepts that divides items into classes according to their shared properties

Question 2

what does it mean if something is polymorphous?

Answer 2

when features are characteristic rather than defining

Question 3

Basic level concept formation in animals, Bhatt, Wasserman, Reynolds & Knauss, 1988

Answer 3

• pigeons in a chamber with choice of four keys
• shown pictures of flowers, cars, people and chairs
• birds learned to peck different keys for examples or each of the four picture categories
• then they tested them with some new examples that they had never seen before
• they were also able to respond correctly to the new examples
• suggests birds had formed “concept” of flowers, cars, people and chaors
• however performance more accurate with the training stimuli (80%) than with the novel test stimuli (60%)

Question 4

what is examplar theory?

Answer 4

Learn about (store) every instance independently.
Classify novel exemplars via similarity to learned instances

Question 5

what is prototype theory?

Answer 5

Learn about (store) abstract prototype corresponding to central tendency of training exemplars.

Question 6

what does exemplar theory predict?

Answer 6

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

Question 7

what does prototype theory predict?

Answer 7

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

Question 8

The prototype effect in pigeons, Aydin and Pearce (1994)

Answer 8

• created a prototype
• artificial positive and negative prototypes defined as ABC and DEF
• The birds trained on three-element displays, created by distorting the prototypes (swapping one prototype element for one from the other category)
• birds taught the three positive patterns always paired with food, the three negative patterns were not
• birds pecked more at positive than negative patterns
• then tested with training patterns and the prototypes, the test of prototype theory is whether they are more accurate with prototype they have never experienced
• The birds responded more to the positive prototype ABC than to any of the positive patterns, and less to the negative prototype, DEF, than to any of the negative patterns
• evidence of a kind of prototype effect
• Narrowing the gap humans and animals more similar than we thought

Question 9

Lists 1, 2 and 3 all differ from prototype by two letters
equally similar to prototype, Whittlesea (1987)

Answer 9

• Studied list 1 tested with lists 1, 2 and 3
• but examples in List 1 more similar to examples in List 2 than examples in List 3
• If they have learned prototype, Lists 1, 2 and 3 equally similar to prototype should be equally good at categorising Lists 1, 2 and 3 – all differ from the prototype by two letters list 1 = list2=list3
• But if learned exemplars in list 1, these are more similar to examples in List 2 than examples in List 3; so List 1 should be easiest (studied),
  then List 2 (differs a little from List 1) and then List 3 (differs a lot from List 1)
  List 1 > List 2 > List 3

Question 10

How do humans show consistent with examplar theory

Answer 10

Prototype: predicts List 1 = List2 = List 3
Exemplar: predicts List 1 > List 2 > List 3

• Pretest with all stimuli: 30ms presentation followed by a mask; then had to write down as many letters as they could
• Score is improvement from pretest (high scores = good)
• List 1 was easier than List 2, which was easier than List 3
• list 1 score: 1.07
• list 2 score: 0.80
• list 3 score: 0.51

Question 11

How can exemplar theory explain the prototype effect?
using to Aydin & Pearce’s experiment on pigeons

Answer 11

• 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 which is more than training examplar
• If exemplar theory assumes each stimulus comprises a set of component features, that are more or less associated with category membership (here food/no food), then can explain prototype effect
• This explanation is actually viewed as a new theory - “feature theory”
• They both say you store something about the stimuli on each trial
• Exemplar theory – learn about/store each whole exemplar
• new stimuli classified on similarity of whole stimulus to stored exemplars
• Feature theory – learn about/store component features of each exemplar
• new stimuli classified on basis of sharing features with stored exemplars
• They can probably both explain the prototype effect
  (but easier to show with feature theory)

Question 12

what is blocking?

Answer 12

• pairing only produces association between X and Category if Category surprising
• If try and associate X with category in presence of Feature already predicting that category, X then Category association will be blocked

Question 13

Experiment by Shanks (1990; cf. Gluck and Bower,1988)

Answer 13

• subjects given trials in which medical symptoms paired with a disease diagnosis
• subjects must predict disease from symptoms
• symptom → disease association
• given 2 diseases, one common e.g. flu and one rare e.g. neuroscience allergy
• one target symptom: (a-headache) and two nontarget symptoms (b- a runny nose, c-rash)
  trails that participants experienced:
• 24 runny nose → flu
• 6 runny nose & headache →flu
• 6 rash & headache →NA
  asked which does headache predict more - flu or NA?
• same number of pairings - 6
• BUT when headache paired with flu, runny nose is present
• and when headache paired with NA, rash is also present
• and runny nose predicts flu much better (24) than rash predicts NA (6)
• so less surprising when paired with headache than NA is when paired with headache → poorer leaning about flu

Question 14

what is a nonassociative account?

Answer 14

predicts that, given headache, subjects will be
just as likely to predict flu as NA (pairings important) flu = NA

Question 15

what is associative theory?

Answer 15

predicts that, given headache, subjects will be
more likely to choose rare NA than common flu (surprise important) flu < NA

Question 16

what theory is better?

Answer 16

Proportion common disease (flu) diagnoses: .37
Proportion rare disease (NA) diagnoses: .63

• Participants more likely to predict that a headache will produce NA
• Associative theory wins
• suggests that associative learning is the best explanation for performance on this category task in human subjects

Question 17

what are subordinate categories?

Answer 17

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

Question 18

Wasserman, De Volder & Coppage, 1992

Answer 18

• Pigeons trained with slides of people, chairs, cars and flowers
• The birds reinforced for making Response 1 to either cars and flowers
• people and chairs in one category, cars and flowers in another
• They made response 3 to people and response 4 to cars tested chairs and flowers, with choice of response 3 and response 4
• would they also make response 3 to chairs and response 4 to flowers

Question 19

superordinate level concept formation in animals

Answer 19

• birds formed superordinate category
• this means they treat people and chairs as equivalent because both paired with the same response in the first place
• a more complex type of categorisation because category members not physically similar

Question 20

Abstract concept formation in animals

Answer 20

• relatively little done on abstract concepts in animals
• the one that has been studied is same/different, usually studied using match-to-sample techniques (MTS)
• birds shown a sample key e.g. red; then given a choice of red and green
• must peck the same colour as the sample - i.e. red.
• on the other trials bird must get a green sample; then task is to peck the green comparison
• found birds could master this, but were typically poor at transferring the skill to different colours (e.g. blue and yellow)
• this suggests that they had not really learned the concept of same

Question 21

complex training techniques with birds for better results study, Wasserman, Hugart and Kirkpatrick-Steger (1995)

Answer 21

• pigeons shown complex 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