james r hurford language evolution and computation
play

James R Hurford Language Evolution and Computation Research Unit, - PowerPoint PPT Presentation

PROTO-HUMAN COGNITION IN NON-HUMAN ANIMALS James R Hurford Language Evolution and Computation Research Unit, University of Edinburgh Descartes Animals as automata, and humans as automata+Reason Darwin Humans are evolutionarily related to


  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 Species Visible/invisible How long? Domestic chicks Neither Squirrel Visible only monkeys Cotton-top Both tamarins Parrots Both Dogs Both Up to 4 mins Chimpanzees Both Overnight Humans over 3 Both Very long times

  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.

  9. 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.

  10. 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.

  11. 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.

  12. Animals form perceptuo-motor categories Only apes and humans can use these categories in further learning. Reversal learning experiments

  13. Reversal Learning Training regime Prosimians Great apes First session: Stimulus-1 > reward Association of Formation of Concept Stimulus-2 > nothing Stimulus-1 with reward. of Stimulus-1, and . association with reward. Second session: Stimulus-1 > nothing Association of Application of negation, Stimulus-2 > reward Stimulus-2 with reward. or oppositeness to . (Di � cult unlearning Concept of Stimulus-1 . and relearning.) NOT( Stimulus-1 ) . associated with reward. . (Relearning facilitated by . use of acquired concept.)

  14. 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)

  15. 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

  16. The size and shape of minimal subscenes “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).

  17. Watch carefully: how many stars are there?

  18. 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 .)

  19. 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)

  20. • 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.

  21. Primacy of objects In a given perceptual scene, different languages tend to agree in the way in which they conflate perceptual information into concrete objects, which are then lexicalized as nouns. There is more variation in the way in which languages conflate relational components into the meanings of verbs and other predicates. To put it another way, verb conflations are less tightly constrained by the perceptual world than concrete noun conflations. Loosely speaking, noun meanings are given to us by the world; verb meanings are more free to vary across languages. (Gentner, 1981, p.169)

  22. There is some human-universality in how we carve up actions and events into manageable packages. Schleidt and Kien (1997) analyzed film of ‘the behavior of 444 people (women, men, and children) of five cultures (European, Yanomami Indians, Trobriand Islanders, Himbara, Kalahari Bushmen)’ (p.7). Based on careful definitions and cross-checking by independent analysts, they found that ‘human action units are organized within a narrow and well-definable time span of only a few seconds. Though varying from 0.3 seconds up to 12 seconds or more, most of the action units fall within the range of 1-4 seconds’.

  23. Perceptual events last for about three seconds. We re-analyze scenes roughly every three seconds.

  24. Nicaraguan Sign Language evolved from small sentence-packages to larger ones. 1st cohort 2nd cohort later ISN MAN PUSH WOMAN FALL > MAN WOMAN PUSH FALL > MAN PUSH WOMAN . MAN PUSH FALL WOMAN (Sequence of two (Verbs brought adjacent) (Adjacent verbs Noun-Verb clauses) collapsed to one) This is now near the natural limit for simple clauses.

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

Recommend


More recommend