Comparative psychology Concept learning Number Time Conditional learning

2. Comparative psychology Concept learning Number Time Conditional learning Just more stuff that animals can do? NO! Associations are for all of us – and they are clever! Don’t just glue things that occur together – sensitive to correlations – can track causal relationships ...and in man they can do clever stuff: connectionist networks – language, pattern recognition so can animals do clever stuff too?

3. Comparative psychology Concept learning Number Time Conditional learning Asks -- How do animals do these things? Is it the same way as humans do them? Need to analyse tasks to ask these questions Learn more about our abilities too

4. C82NAB Neuroscience and Behaviour Categorization and concept formation Charlotte Bonardi

8. Concept: The mental representation of something. Many concepts are based on the sharing of common properties by items in a class. Concept formation: The induction of concepts that divide items into classes according to their shared properties (categorization).

9. Note that concepts are not always defined by specific features... sometimes do not have NECESSARY or SUFFICIENT features to define them... "polymorphous"e.g. What is the defining feature of a game?

11. even simple things like tables...

12. even simple things like tables...

13. Types of concept: (i) Basic level concept -- based on similarity of perceptual qualities (e.g., bird, flower).(ii) Superordinate concept -- groups of basic level concepts; not based on perceptual similarity (e.g. politician, tools).(iii) Abstract concept -- does not refer to individual entity, but to some property, relation or state (e.g., sameness, truth).

14. Questions.. Can animals form basic level concepts? superordinate concepts?abstract concepts? If so, how do they do it? Do animals form concepts in the same way as humans?

15. Basic level concept formation in animals Bhatt, Wasserman, Reynolds & Knauss, 1988 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 the four categories of picture. chair people car flower

17. Basic level concept formation in animals Bhatt, Wasserman, Reynolds & Knauss, 1988 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 the four categories of picture. Then they tested them with some new exemplars, that they had never seen before......

19. Basic level concept formation in animals Bhatt, Wasserman, Reynolds & Knauss, 1988 They also were able to respond correctly to the new exemplars, that they had never seen before. This suggests that the birds had formed a “concept” of flowers, cars, people and chairs. However, performance was more accurate with the training stimuli (80%) than with the novel, test stimuli (60%).

20. Theories of basic level concept formation -- how do they do it?: (i) Exemplar theory: Learn about every instance independently. Can classify novel exemplars on the basis of similarity to learned instances. (ii) Prototype theory: Abstract a prototype that corresponds to the central tendency of training exemplars. Classify novel exemplars on basis of similarity to protype.

21. Animals are clearly storing information about the training exemplars -- which is why they were more accurate with them than with the novel test stimuli. This implies their performance can be explained by exemplar theory Theories of basic level concept formation -- how do they do it?:

22. Animals are clearly storing information about the training exemplars -- which is why they were more accurate with them than with the novel test stimuli. This implies their performance can be explained by exemplar theory However, it is reported that humans show the prototype effect (e.g., Homa et al., 1981) -- they categorize the prototype more accurately than the training stimuli, even if it has never been seen before This is more consistent with prototype theory ... and doesn’t seem to fit exemplar theory Theories of basic level concept formation -- how do they do it?:

23. So do animals store examplars and humans a prototype? Are humans and animals forming basic-level concepts in different ways? Red Rag to a Bull! so someone tries to show a prototype effect in animals... Theories of basic level concept formation -- how do they do it?:

24. Aydin & Pearce, 1994. The prototype effect in pigeons: A B C D E F

25. Aydin & Pearce, 1994. The prototype effect in pigeons: A B C D E F The positive and negative prototypes are defined as ABC and DEF... ABC + DEF -

26. ABC + DEF - The birds trained on three-element displays, created by distorting the prototypes (swapping one prototype element for one from the other category): + + +

27. ABC + DEF - The birds trained on three-element displays, created by distorting the prototypes (swapping one prototype element for one from the other category): + + +

28. ABC + DEF - The birds trained on three-element displays, created by distorting the prototypes (swapping one prototype element for one from the other category): -- -- --

29. ABC + DEF - The birds trained on three-element displays, created by distorting the prototypes (swapping one prototype element for one from the other category): -- -- --

30. The animals were taught that the three positive patterns were always paired with food, whereas the three negative patterns were not. Birds pecked a response key more at positive than at negative patterns.

31. The animals were taught that the three positive patterns were always paired with food, whereas the three negative patterns were not. Birds pecked a response key more at positive than at negative patterns. Then the birds were tested with the training patterns and the prototypes....

33. 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. This is evidence of a kind ofprototype effect (though not everyone thinks this evidence is good enough - pigeons fail to learn more complex prototypes)

34. Narrowing the gap... humans and animals more similar than we thought... so let’s ask the converse question – do humans store exemplars as well?

35. Whittlesea, 1987 But do humans store information about the training items...? Prototype FURIG 1 FEKIG FUTEG PURYG FYRIPKURIT 2 FYKIG FUTYG PUREG FERIPPURIT 3 FUKIPPUTIG FURYT FYREG KERIG

36. But do humans store information about the training items...? Whittlesea, 1987 Prototype FURIG 1 FEKIG FUTEG PURYG FYRIPKURITSTUDY 2 FYKIG FUTYG PUREG FERIPPURIT 3 FUKIPPUTIG FURYT FYREG KERIG Pretest with all stimuli (30ms presentation followed by a mask; then had to write down as many letters as they could). Studied list 1 Tested with lists 1, 2 and 3.

37. Whittlesea, 1987 PrototypeFURIG 1 FEKIG FUTEG PURYG FYRIPKURIT 2 FYKIG FUTYG PUREG FERIPPURIT 3 FUKIPPUTIG FURYT FYREG KERIG If they have abstracted the prototype, then they should be equally good at categorising 1, 2 and 3, as they all differ from the prototype by two letters...

38. So do we abstract a prototype? maybe not... Whittlesea, 1987 Prototype FURIG 1 FEKIG FUTEG PURYG FYRIP KURIT 2 FYKIG FUTYG PUREG FERIP PURIT 3 FUKIPPUTIG FURYT FYREG KERIG But if they are remembering the exemplars, they should be best with 1 (studied) and better at 2 than at 3 – list 2 more similar to list 1 than list 3.

39. Prototype theory says subjects should be equally good at lists 1, 2 and 3 -- all equally similar to the prototype. Exemplar theory says list 1 should be easiest (studied), then list 2 (differs a little from studied list) and then list 3 (differs a lot from studied list) And that is what they found... 1 1.07 2 0.80 3 0.51 (improvement from pretest)

40. Conclusion: Both humans and animals retain information about the training items/exemplars (consistent with exemplar theory) So what about prototype theory? It turns out that exemplar theory can even explain the prototype effect! The two theories do not make very different predictions after all. How? Let’s go back to Pearce’s experiment: we need to explain why birds peck more at positive prototype than to other members of the positive category

41. Prototypes A B C + D E F - Training stimuli: + + + -- -- --

42. Positive Prototype Positive Trained stimulus A B C + Training stimuli : + + + -- -- --

43. Positive Trained stimulus Training stimuli: + + + -- -- --

44. Positive Trained stimulus Training stimuli: + + + -- -- --

45. Positive Trained stimulus five positive, four negative Training stimuli: + + + -- -- --

46. Positive Prototype Positive Trained stimulus five positive, four negative Training stimuli: + + + -- -- --

47. Positive Prototype Positive Trained stimulus five positive, four negative Training stimuli: + + + -- -- --

48. Positive Prototype Positive Trained stimulus six positive, three negative five positive, four negative Training stimuli: + + + -- -- --

49. Conclusion: If exemplar theory assumes that each stimulus is composed of a set of elements, that are more or less associated with category membership, then it can explain the prototype effect This explanation is actually viewed as a new theory "feature theory"

50. Feature theory versus Exemplar theory The difference between feature theory and exemplar theory is subtle. They both say you store something about the stimuli on each trial Exemplar theory implies that each stimulus is a configuration -- new stimuli classified on basis of similarity to stored configures Feature theory says that each stimulus is composed of a set of elements, -- new stimuli classified on basis of sharing stored elements