PROTO-HUMAN COGNITION IN NON-HUMAN ANIMALS James R Hurford Language Evolution and Computation Research Unit, University

1. PROTO-HUMAN COGNITION IN NON-HUMAN ANIMALS James R Hurford Language Evolution and Computation Research Unit, University of Edinburgh

2. Descartes Animals as automata, and humans as automata+Reason Darwin Humans are evolutionarily related to apes and all other animals. Morgan's Canon “In no case is an animal activity to be interpreted in terms of higher psychological processes, if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development.” Anthropomorphism versus continuity

3. Seeds of language: precursors of aspects of language in animal life • object permanence, • episodic memory, • metacognition, • competence with abstract relations, • transitive inference, • subitizing, • the where/what-dorsal/ventral separation, • global and local attention. • `frame-of-reference' systems,

4. Displaced reference Human language enables us to refer to things distant in time and space. No animal communication system allows the animal to refer to distant things, (except honeybee communication). But many animals can solve object permanence tasks.

5. Relative performance on object permanence

6. A solipsistic, private view of the origins of reference. Private attention to objects (visible or hidden) is the basis for later-evolved public reference to objects (e.g. via language). Animals’ abilities in object permanence tasks are the evolutionary seed of displaced reference in language.

7. Episodic memory (mental time travel) Humans describe specific events, often in the distant past (or future). Tulving (and Suddendorf) claims that episodic memory is unique to humans. But there are degrees of ‘episodic-like’ memory. ‘Episodic-like’ memory in animals is usually restricted to the domains animals are interested in (e.g. food).

8. Clayton et al.: Scrub jays remember where they hid food, of what type and how long before. Schwartz & Evans: apes have episodic-like memory. MacDonald: Gorillas could remember where food was hidden 24 hours later. Schwartz: the gorilla King could remember the order in which he had been given food items, 5 minutes apart. (Backwards only!) Schwartz: the gorilla King could remember which of three possible events, which had no lasting effect, he had seen up to 15 minutes earlier. Menzel: The chimp Panzee could remember the hiding of food several days later.

9. Episodic memory – a methodological problem Did Panzee recall the hiding of food (episodic memory) or where food lies hidden (semantic memory)? How could we tell the difference? Humans are “inferentially promiscuous” (Susan Hurley) Possible experiment: (1) Prominently show a chimp a key being placed on a high shelf – this should be a salient event, but irrelevant (yet) to the chimp’s normal life. (2) Later, train the chimp to connect the key to the unlocking of a food cupboard; (3) one day, appear to have lost the key, and see if the chimp ‘tells’ you it is on the shelf.

10. Metacognition Humans express propositional attitudes to states of affairs. E.g. I (don’t) know/believe/think/hope that this is correct. “When an organism knows what it knows, its actions are different from an organism that is locked out of its library of knowledge” (Marc Hauser) Uncertainty monitoring: Smith and Washburn: Pigeons and chimpanzees trained to respond `Yes’, `No’ or `Don’t know’. The ‘Don’t know’ response typically takes longer than the more certain responses and is given at the borderline between categories. Keddy-Hector et al. Piglets backing out of a maze when they `realize’ they have made a wrong choice.

11. Animals can represent abstract properties and relations Alex the parrot. What colour is this? Red RED(x) COLOUR(RED) What’s same about these? Shape. SQUARE(x), RED(x), PLASTIC(x) SQUARE(y), BLUE(y), WOOD(y) SQUARE(z), GREEN(z), GLASS(z) SHAPE(SQUARE)

12. Animals can represent abstract properties and relations Relations between relations SAME DIFFERENT DIFFERENT DIFFERENT DIFFERENT SAME

13. Animals can do transitive inference Baboon social hierarchy (3160 possible pairs) (X dominates Y & Y dominates Z) X dominates Z Chickens submit to a chicken who has beaten a chicken who has beaten them. Chickens challenge a chicken who was beaten by a chicken they have beaten. Lab studies on ordering: A > B > C C > D > E A > G E > F > G

14. “The magical number 4” (Nelson Cowan) Short-term memory is limited to about 4 objects. Subitizing collections of objects, up to about 4. Human sentences are limited to about 3 participants (subject, direct object, indirect object).

15. Watch carefully: how many stars are there?

16. There is a psychological limit on perceivable discrete numerosity around 4-5. Short-term memory (Nelson Cowan, “The Magical Number 4”) Many animals can discriminate discrete numerosities up to about 3-4. (Stanislas Dehaene, The Number Sense.)

17. For any language, the maximum number of obligatory noun phrases in any sentence (with any verb) is 3. E.g. Mary awoke (1 NP) Mary ate breakfast(2 NPs) Mary put her keys on the table (3 NPs)

18. A limit of four objects in visual working memory (Luck and Vogel, 1997) • Mean short-term memory capacity in adults of 3-5 chunks (Cowan, 2001) • Deictic subsystems are limited to about three degrees of difference (e.g. Japanese ano, kono, sono). • Minimal subscenes (Arbib) contain up to about four separate participants. The basic clauses of languages are adapted to describing such minimal subscenes.

19. Animals (don’t) have propositional representations of the world Logically minimal propositions: E x [LION(x)] There is a lion

20. Many animals have simple predicate-argument structure. • The most basic semantic distinction is between predicates and arguments – PREDICATE (x). • This asymmetric relation is the first sign of semanticstructure. • The innermost brackets in any complex semantic formula are those separating predicates from their arguments: • believe(john, ( x y (woman(x) & man(y) & love(x,y)))) E A

21. Many animals have simple predicate-argument structure. A parallel between the predicate-argument structure PREDICATE(x) and distinct neural mechanisms for (i) Attending to an arbitrary object - (x) - (via the dorsal stream), (ii) Categorizing an object - PREDICATE(x) - (via the ventral stream).

22. (z) RED(z) Dorsal stream locates object Ventral stream categorizes object (x) (y) (z)

23. Posterior Parietal Cortex Pulvinar Superior Colliculus Dorsal Stream Lateral Geniculate Nucleus dorsalis Primary Visual Cortex Retina Ventral Stream Infero-temporal Cortex (After Milner & Goodale, 1995)

24. `` ... the most primitive contact that the visual system makes with the world (the contact that precedes the encoding of any sensory properties) is a contact with what have been termed visual objects or proto-objects ... As a result of the deployment of focal attention, it becomes possible to encode the various properties of the visual objects, including their location, color, shape and so on.'' (Pylyshyn (2000):206)

25. So, I am committed to one-place predicates as the basis for representations of scenes/objects/events in animals. • How can at least some scenes/objects/events be represented solely in terms of one-place predicates? • (More in my talk at 4.00pm.) But here I appeal to two psychological themes: • Global versus local attention • Frame of Reference

26. Global and local attention

27. Quick global attention delivers something like RED YELLOW PURPLE DANCE GIRL SKIRT GIRL with predicates only approximately bound

28. Global and local attention

29. Another example

30. Quick global attention delivers KISS GIRL BOY SMILE

32. Frame of Reference Judgements are maderelative to theircontexts. E.g. What is judged as WHITE in half-light is judged as GREY in full light. Jokisch & Troje (2003) Fast-striding animals are seen as relatively small, and slow-striding animals are judged to be relatively big. Sarris (1998) Chickens can be trained to make perceptual judgements such as ‘big for a red cube’ and ‘small for a green cube’.

33. An iconic notation, taking a cue from event semantics KISS AGENT BOY PATIENT GIRL SMILE Boxes correspond to individual variables, e, w, x, y, z. KISS(e) & AGENT(x) & BOY(x) & PATIENT(y) & GIRL(y) & SMILE(y)

34. An iconic notation, taking a cue from event semantics AGENT GIRL SMILE Boxes correspond to individual variables, e, w, x, y, z. AGENT(y) & GIRL(y) & SMILE(y) (No ontological distinction between a one-participant event/state and an individual object.)

35. Thank you.