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12/7/2015 PSY 2364 Animal Communication Homework assignment #2 Comparison of animal communication and human language • Due date: Wed. Dec. 9 • List and describe a set of universal properties that are found in language. (a) To what extent are these properties unique to language? (b) To what extent are they also found in animal communication systems? Give examples where appropriate. • • Prosimians Ceboid (New World) monkeys – C. & S. America Apes Lemurs – Madagascar Lorises, galagos and their allies – Africa, Asia Tarsiers (tarsiers, tree shrews) – Philippines, S.E. Asia Monkeys Order: Primates Cercopithecoid (Old World) monkeys – guenons, mangabeys, macaques, baboons, langurs, etc. Lesser Apes (Hylobatidae) – gibbons and siamangs Great Apes (Pongidae) – chimpanzees, bonobos, gorillas, orangutans Approximately 2 double-spaced, typed pages Submit by via eLearning Primate evolution • • Primates are intelligent animals. What factors are linked to higher intelligence? 1. 2. 3. 4. Arboreal living Sociality Fine motor skills Diurnal life style Humans (Hominidae) Primate evolution • • Brain-body size Primates are intelligent animals. What factors are linked to higher intelligence? 5. Generalized adaptation to greater environmental complexity 6. Large size 7. Large brains 8. Longevity The brain of a horse (Equus caballus) is more than six times bigger than that of a rhesus monkey (Macaca mulatta). But if they were equated for body size, the monkey would have a 20x larger brain. 1 12/7/2015 Brain-body size Diet and brain size • Within the primates, species that eat fruit tend to have relatively larger brains than species that mainly eat leaves. Spider monkey Fruit diet Neocortex • The neocortex is the layered outer shell of the brain, and is found only in mammals. • Primates show expansion of the neocortex. • In humans 80% of the brain is taken up by neocortex, compared to less than 20% in shrews. Howler monkey Leaf diet Neocortex • Convolutions (wrinkles) in the primate neocortex provides increased surface area. Cortical plasticity Most primates are social animals • An important property of the neocortex is plasticity. This term refers to changes that take place in the neocortex when connections are formed or strengthened along frequently used neural pathways, or when unused connections are weakened or lost. During the lengthy period of juvenile development, the wiring of the primate neocortex is modified through learning and interaction with the environment. • Most species of primates live in social groups consisting of both males and females and young. • Members of the group may spend their entire life with the same individuals, and get to know each other well. • The context of a communication signal includes a network of social relations that have a long history. This history helps determine how a signal is interpreted and responded to. 2 12/7/2015 Social learning • Observation-based learning • Food sharing – White-faced Capuchin monkeys – Chimpanzees: termite fishing – see Dugatkin p. 174-175 Social Learning • Copying Social learning • Learning by imitation – Developing a behavior as a result of observing another individual performing that behavior – Manipulation of objects to reach a desired outcome (e.g. potato washing in macaques) – Strategy for reaching a goal may be specific (budgerigars adopt different strategies to uncover food (beak vs. foot) depending on what the model did; Galef, 1986) Social Learning • Teaching (pedagogy) – Observer repeats the behavior of another individual – Sometime accompanied by rewards – Differs from imitation in that the action does not need to be novel, nor does it necessarily involve a topographically novel response. Vocal learning • How much of primate communication is the result of learning? (1) producing the appropriate call (acoustic structure); – One individual serves as the instructor, the other as the student who learns from the teacher – Implies an immediate benefit for the student but not for the teacher – Examples: hunting in cheetahs Vocal learning • Production of calls is largely independent of experience and learning (but studies are limited). (2) using the call in the appropriate social context; (3) understanding the significance or responding to the call in the appropriate manner. –Winter et al. (1973) found that infant squirrel monkeys developed normal vocalizations even if they were deafened when 4 days old, or when raised in isolation. 3 12/7/2015 Old World monkeys • • • • • • • • Call classification by vervet monkeys • Vervet monkeys give acoustically distinct calls for different predators, and result in different behavioral responses: Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Primates Family: Cercopithecidae Genus: Chlorocebus Species: aethiops – Leopards (run and climb into trees) – Eagles (look up, run into bushes) – Snakes (mobbing response) Vervet monkey Vocal learning • Perception of calls may be shaped by learning. – Infant vervet monkeys do not produce any alarm calls before the age of 1 month, and only rarely at 6 months. – Infant vervet monkeys often produce alarm calls in the wrong setting, but they improve with age (learning by imitation). Vocal learning • Cheney and Seyfarth (1996): Vervet monkeys appear to interpret the calls as sounds that represent objects and events in the external world. • If a vervet monkey is habituated to the leopard alarm call (by playing it repeatedly without a leopard in the vicinity) the animal stops responding . • Playback experiments (Cheney & Seyfarth, 1988) elicit the same responses, even when the predator is absent Vocal learning • Perception of calls may be shaped by learning. – Vervets younger than 3-4 months run to their mothers when they hear alarm calls. After hearing an alarm call they often look at their mother. By 6-7 months they respond in the same way as adults. – Vervets also respond to alarm calls given by birds, such as the Superb Starling. This is probably a learned behavior. Vocal learning • A recording of the eagle alarm call produced by the same individual does not produce any response either. • But a recording of the eagle alarm call produced by a different individual produces the expected response (hiding in bushes). 4 12/7/2015 Evidence for vocal learning • How much of primate communication is the result of learning and imitation? (1) producing the appropriate call (acoustic structure); (2) using the call in the appropriate social context; (3) understanding the significance or responding to the call in the appropriate manner. • Production of calls largely independent of experience and learning (but studies are limited) Primate life styles • Most primates are arboreal (forest, jungle). • Some old world monkeys (e.g. olive baboons) are terrestrial, i.e. adapted to living and foraging on the ground. • Some apes (gorillas, chimpanzees) spend a lot of time on the ground. • No primates are exclusively terrestrial. • What about perception? Primates – physical traits • Features shared with other mammals – e.g., giving birth to live young, fed on milk • Features that define primates as unique – – – – – tendency toward erect posture prehensile (grasping) limbs 5 digits on hands and feet opposable thumb; fingernails rather than claws long gestation period, delayed maturation, long lifespan Primates – diet • Most primates are omnivorous and eat a combination of fruits, seeds, leaves, and insects • Some species kill and eat small mammals • Some eat mainly leaves Primates – sensory systems Primate communication systems • Binocular vision: eyes positioned in the front of the face provides capacity for depth perception and stereoscopic vision. • Color vision: Diurnal primates see in color; nocturnal primates lack color vision. • Acute hearing • Reduced reliance on olfaction • Expanded brain size (cerebral hemispheres) • Primate communication is multimodal (vocalizations, facial expressions, gestures, postures, tactile contact signals, olfactory signals). • Primate communication takes place within an extended context, not in isolation – same sound may appear in different situations – context helps to determine meaning (response) 5 12/7/2015 Marler (1965) • Multimodal signals • Long-term social contacts • Short-range signals – calls, visual gestures and postures, contact • Long-distance signals – usually unimodal, because of signal degradation – specialized structures for long-distance vocalization (throat pouches used for long calls by howler monkeys and siamangs) Variety of message states • • • • • • Submissiveness Aggression Anxiety Fear Mating and courtship signals Parent-infant interactions Culture in chimpanzees? • Whiten, Goodall, McGrew, Nishida, Reynolds, Sugiyama, Tutin, Wrangham and Boesch (1999). Culture in chimpanzees. Science 399: 682-685. • Field studies from 7 long-term studies revealed patterns of variation far more extensive than previously recorded for any animal species except humans. • 39 different behavior patterns including tool usage, grooming and courtship behaviors consistent with the idea of cultural transmission. Marler (1965) • Discrete versus graded signals – many primate signals are graded; variations in meaning are correlated with small changes in behavioral pattern rather than discrete and different behaviors. • Graded signals are well suited for conveying messages along a continuous scale (e.g. degree of confidence or aggression level). • Discrete signals are well suited for delivering a single message (e.g. vervet monkey alarm calls) Variety of message states • Signals to coordinate group movements, dispersal – increase distance (territorial exclusion) – maintain distance (constant spacing of adjacent troops) – reduce distance (bring animals together) • Environmental information – So far, restricted to alarm calls for different types of predator Cultural Transmission • Transfer and acquisition of information via social learning and teaching • Learned patterns are passed on from one individual to another • Cultural transmission involves a “model” and an “observer” who learns a specific behavior from the model 6 12/7/2015 Cultural Transmission • Vertical transmission: information is passed from parent to offspring – Some songbirds learn the species-specific song by listening to their father sing – “Sponging” behavior in dolphins: learned behavior in female bottlenose dolphins, who break off a piece of marine sponge to protect their mouths when probing the sea floor for fish prey Cultural Transmission • Horizontal transmission: information is transmitted from peer to peer – Guppies form foraging groups with peers of similar age and size – Laland &Williams (1998) trained 2 groups of guppies. One group trained to follow a short path to a food source, the other a long path. When new members were added to each group, they adopted the learned strategy of the group. Cultural Transmission Snake aversion in monkeys • Oblique transmission: information is transmitted across generations but not from parent to offspring • Lab-raised monkeys who have never seen a snake do not respond in the same way as wild-raised primates who have seen them. • Observing an adult model respond to snakes with fear gestures and actions, a juvenile rhesus monkey adopts the same gestures. • This happened even when the model was not related to the juvenile (oblique transmission) – Common in species with no parental care – Predator recognition in blackbirds – Snake aversion in rhesus monkeys Snake aversion in monkeys • In one condition juveniles observed an adult monkey who had been conditioned to show a fear response in the presence of a neutral object (flowers). But in this situation the juvenile did not display fear when exposed to flowers, suggesting an interaction of oblique transmission with an innate predisposition to fear snakes. Local enhancement • Not all interactions between individuals involve cultural transmission. – Local enhancement describes situations where one individual is attracted to an area because of the actions of another individual (or group of individuals) that are already there. Learning is not the result of observing another’s behavior. – Example: Cliff Swallows find good foraging areas by looking for crowds of swallows. 7 12/7/2015 Social facilitation • Not all interactions between individuals involve cultural transmission – Social facilitation describes situations where the mere presence of an individual in an area facilitates learning on the part of another animal. – Example: increased group size leads to increased foraging rates in Starlings. Cultural transmission • Interaction of cultural transmission and genetic inheritance • Learning and transmission of bird song in Galapagos finches – Learned behaviors may serve as reproductive isolating mechanism – Females selectively mate with males who sing the species-specific song Foraging behavior • Experiments on the use of a novel food source by Capuchin monkeys (Cebus paella). The novel food source was sampled by a lone monkey only when it was in view of other monkeys eating a different type of food; not when the other monkeys were present but not eating anything (supports local enhancement, not social facilitation). Cultural transmission and brain size • Studies of primate brain anatomy indicate a significant positive correlation between brain size and the frequency of tool use, social learning and innovation. • In this study, brain size was a better predictor than brain-body ratio. Hockett’s design features of language What is language? Bee dance Bird song Language Vocal-auditory channel • Hockett’s design features of language: • All human languages share 16 basic properties that distinguish language from other forms of communication in animals. • Some (but not all) of these properties may also be found in animal communication systems. Rapid fading Charles Hockett (1966). The Problem of Universals in Language. Interchangeability Total feedback Specialization No Yes Yes ? Yes Yes Some ? Yes ? Yes Yes ? Yes Yes Semanticity Yes Yes? Yes Arbitrariness No Yes? Yes Discreteness No ? Yes Displacement Yes ? Yes Productivity Yes ? Yes Traditional transmission No Yes Yes Duality of patterning No ? Yes 8 12/7/2015 Levels of linguistic analysis Phonetics 1. Phonetics – speech sound production/perception 2. Phonology –patterning of sounds (phonemes) in a language • Speech sound production • Speech sound perception 3. Morphology – principles of word (morpheme) formation 4. Syntax – organization and arrangement of morphemes in sentences 5. Semantics – study of meaning 6. Pragmatics – language use in social context Phonology • Phonology is the study of sound patterning in a given language • Phonemes are the sound units in a given language Phonology • Phonemes – Small units of language; do not convey meaning by themselves – Minimal pairs test (“pit” vs. “bit”) – American English has 12 vowels (e, o, u, …) and 24 consonants (p, t, k, …) Morphology Syntax • Morphology is the study of word construction in a given language • Morphemes are the smallest units in a language that carry meaning • Syntax is the study of the principles and rules for constructing sentences in a language. • Units of syntax are the traditional “parts of speech” (nouns, verbs, adjectives, adverbs) • Syntactic theories describe the rules of sentence construction (rules of grammar) – Morphemes are similar to words, but some words consist of more than one morpheme – dogs = ‘dog’ + ‘s’ (plural marker) – Formal mathematical theories – Characterization of grammatical knowledge (Chomsky) 9 12/7/2015 Semantics • Semantics is the study of meaning – – – – Lexicon (dictionary) Color terms Kinship terms Cross-language comparisons Language acquisition • Critical period for language acquisition? • Hemispheric specialization • Recovery from aphasia • Stages of language development • “Motherese” (infant-directed speech) • Prosody of speech Milestones of speech development (P. Kuhl, Nature Neuroscience Reviews, Nov 2004) Infant-directed Speech • Limited vocabulary, concrete reference – doggie, potty, choo-choo train, boo-boo • Simple syntax: short sentences; more imperatives and questions • Precise articulation • Repetition • Exaggerated pitch contours – “what a good boy!” Infant-directed Speech Prosody – melody of speech 1. approval heavily modulated, extensive rise/fall in fundamental frequency (pitch) 2. prohibition ("NO!") 3. attention (shorter than approval, more rapid rise to maximum) 4. comfort (relatively unmodulated, downsweep in fundamental frequency) Infantdirected speech P.K. Kuhl (2004). Early language acquisition: Cracking the speech code. Nature reviews – Neuroscience Volume 5 | Nov 2004 | 831 10 12/7/2015 Learned communication Language and animal communication • • • • • • • Vocal imitation and invention Vocal tract anatomy and motor control Perceptual abilities Brain mechanisms Theory of mind, attribution of mental states Referential signaling Rule-based learning, sign language, artificial language systems • Factors that favor learned communication: – – – – – – – Learned communication Sources of evidence for learning • • • • • • existence of (learned) dialects interspecific mimicry acoustic isolation deafening to remove auditory feedback disruption of neural pathways (CNS lesioning) tape tutoring (birds); social tutoring (captive rearing) • cross-fostering (young reared by adults of another species) Learning and behavior Variability in signal production & perception Individual or group recognition Adaptation to unpredictable environments Need for complex decision making Long period of parental care Stable long-term social interactions Capacity for imitation and invention • Factors that favor learned communication: – – – – – – – Variability in signal production & perception Individual or group recognition Adaptation to unpredictable environments Need for complex decision making Long period of parental care Stable long-term social interactions Capacity for imitation and invention Tool use and learning in crows • Captive New Caledonian crows have learned to develop and use tools to solve complex problems. • This crow was able to bend a piece of straight wire into a hook, and used the hook to lift a bucket containing food from a vertical pipe. • Reference: Weir, Chappell, & Kacelnik Science 297, 981 (2002). • http://www.youtube.com/watch?v=fumsiIGE9c0 11 12/7/2015 Mirror self-recognition Joshua M. Plotnik, Frans B. M. de Waal and Diana Reiss (2006). Self-recognition in an Asian elephant. PNAS 103 (45): 17053–17057. Mirror self-recognition • Previously found only in humans, apes, and dolphins • MSR involves four stages: (i) social response (ii) inspection (e.g., looking behind the mirror) (iii) repetitive mirror-testing (iv) self-directed behavior (i.e., recognition of the mirror image as self) www.pnas.orgcgidoi10.1073pnas.0608062103 Word learning by a dog Word Learning in a Domestic Dog: Evidence for “Fast Mapping”. Juliane Kaminski, Josep Call, Julia Fischer Science 304: 1682-1683. www.sciencemag.org/cgi/content/full/304/5677/1682/ A border collie, Rico, learned the labels of over 200 different items. He inferred the names of novel items by exclusion learning and correctly retrieved those items right away as well as 4 weeks after the initial exposure. 12