Why study animal cognition? To understand the role of nature and nurture in complex, cognitive behaviors Cognition and language do not fossilize. Use same technique as Darwin: comparative method. Did particular components of cognition evolve just for humans and thus are unique to humans.
The case of acquisition of bird song • 9,000 species of birds and virtually all have up to a dozen distinct calls, peeps, buzzes etc/ Songs are longer and highly patterned • In most birds, song is innate: 3 orders show evidence of learning: • Parrots • Hummingbirds • Oscine songbirds (e.g., sparrows)
Certain parallels with human acquisition Different paths to acquiring birdsong 4,000 species of song birds; most show evidence of learning: Isolated birds develop abnormal songs
Case of isolated white-crowned sparrows, e.g., Nelson • http://blb.biosci.ohio-state.edu/nelson.html • Click on “song learning” to left • Click on the 3 spectrograms: song of an isolated sparrow, song of a sparrow exposed to adult song and the adult song
In many species, males are most sensitive to learn songs in the first few months of life: a critical period After critical period cannot compensate for lack of exposure to language
Actual vocal production begins with subsong. Subsong has been compared to babbling in human infants. Example from Nelson: http://blb.biosci.ohio-state.edu/nelson.html • Click on “stages of learning” and then on first spectrogram of “subsong” or babbling. • Next spectrogram shows early learning: relation between youngster’s song and the model song.
Homologue versus analogue • Distinguish between analogous features which are similar in function and form between species AND homologous features which are connected by unbroken line in evolution
Do birds have language? • Is there genetic link to humans? • Analogue or homologue?
Lewontin: what are comparable characteristics in different species? Requires analysis of cognition: • “Are the grunts of a chimpanzee the primitive homologues of Hamlet’s soliloquy?”
Compare to the human eye • Remarkably similar structure of human and octopus eye. Not homologous. Analogous because of constraints placed by laws of optics and need to focus image on receptors
Characteristics touted as uniquely human have been re-evaluated when animal cognition studies, e.g., categorical perception
Why study animal cognition? To better understand the brain. • Look for homologous brain areas
Hemispheric laterality: Thought to be unique to humans, special adaptation for competing modes of processing: language versus spatial processes
Macaque monkeys discriminate between their own vocalizations better than vocalizations of another species and better with their right ear left hemisphere specialization
Broca’s area has a homologous area in monkeys. • When stimulated in monkeys, movement of lips, tongue and face, but no vocalization. • Function of this area has changed between monkeys and humans
Why study animal cognition? To better understand the organization of cognition • Infants may have inherent ability to use language (symbols) because of certain genetic endowments: • Categories versus individuals, Pinker, Marcus
Concept of individual central to human thought • Not based on perceptual properties
Sorrentino (1998) • 3-year olds point to first bear (Zavy) • How do you update connectionist model? • An instance of the kind to which Zavy belongs (teddy bear with bibs) that is in center is more strongly associated with Zavy node than instance not in center locations • Problem of tracking individuals over time
Connectionist networks have problem distinguishing between individuals and kinds (types and tokens)
Where does this ability come from? Do animals have? • Tracking individuals benefits predators, e.g. hyenas and wildebeests • Ability to keep track of where seeds are stashed. Clark’s nutcracker can keep track of 33,000 seed caches • Chicks a few hours old travel in direction of recently occluded object