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Summary of Scientific Contributions
Petitto’s
research and discoveries span several scientific disciplines. Her early
work with Nim Chimpsky and her later work with humans encompasses
Anthropology, Comparative Ethology, Evolutionary Biology, Cognitive
Neuroscience, Cognitive Science, Theoretical Linguistics, Philosophy,
Psychology, Psycholinguistics, American Sign Language, Language Acquisition, Child Development,
Evolutionary Psychology, Deaf Studies, Bilingualism, and Reading Her overall discoveries can be summarized as follows:
- Cross-species (apes and humans) language and cognitive capacities
- The
nature of early human language acquisition, structure, and
representation in the human brain, and, crucially, the brain tissue that
supports it
- The structure, grammar, and representation of natural signed languages of Deaf people, especially American Sign Language
- The
nature of bilingual infants, children, and adults’ bilingual language
and reading development, processing, and brain organization, with key
comparisons to monolinguals
Educational Neuroscience: Petitto
had a leading international role in the creation of a new scientific
discipline that she and her colleagues have termed Educational
Neuroscience (aka Mind, Brain and Education), involving the marriage of
basic scientific discoveries about the developing brain/child with its
principled application to solving core problems in the education of
young children.
Taken together, the major contribution of her scientific
writings have been to offer both testable hypotheses and theory
regarding the neural basis for the brain’s specialization for human
language, and how it is possible for very young babies to acquire
language. These include:
- Using
signed languages as a new “microscope” to discover the
central/universal properties of human language in the brain (those that
are distinct from the modality of language transmission and reception),
Petitto advanced 5 branches of research.
- Universal
Linguistic Structures (cross-linguistic studies of signed and spoken
languages and cross-linguistic studies of different signed languages,
especially ASL and Langue des Signes Québécoise, LSQ
- Linguistic
Timing Milestones in Development (the highly similar maturational
timing in the achievement of language milestones across young children
acquiring spoken and signed languages)
- Universal
Linguistic Structures in Development (the highly similar acquisition of
specific parts of natural language structure, with similar timing and
use, across signed and spoken languages). For example, similar Pronouns,
Pronominal Reference, and Pronoun-Reversals, across young children
acquiring spoken and signed languages, despite the radically different
linguistic form of pronouns in signed languages. The discovery of
rhythmically-alternating, phonetic-syllabic “manual Babbling” on the
hands in babies acquiring signed languages (be they Deaf or hearing),
identical in linguistic structure, timing, and use to vocal Babbling in
hearing babies acquiring spoken languages. For decades, Babbling was
viewed as inextricably tied to sound and speech. However, the discovery
of hand Babbling demonstrated that rather than sound being key, Babbling
reflects the infant’s biologically-given sensitivity to highly specific
patterns that are part of language structure. The discovery forced a
reconceptualization of the nature of human Language by decoupling Speech
and Language. Featured on both the
cover of Science and the front page of the New York Times on the same
day.
- Distinct Knowledge
Representation in Development (domain-specific versus domain-general
knowledge in child development; the difference between language versus
communicative gesture in all children’s development; the acquisition of
pronominal reference, and pronoun reversals, versus gestures in young
Deaf children acquiring ASL and young hearing children acquiring spoken
language)
- Brain Tissue
Dedication for Aspects of Human Language Structure and Processing
(convergences of specific linguistic functions on specific brain tissue
across signed and spoken languages). For example, previously regarding
spoken language, phonological processing was found to occur in the left
hemisphere's (LH) Superior Temporal Gyrus (brain tissue regarded as
unimodal sound processing tissue for 125 years), and the Left Inferior
Frontal Cortex was regarded as the brain's site for the search and
retrieval of information about word meanings (due to its proximity to LH
speech production mechanisms). However, Petitto and her team found that
the same brain tissue recruitment is used when processing the same
parts of language regardless of whether the language was on the hands in
signed language or the tongue in spoken language. Petitto is associated
with advancing the new hypothesis (a new understanding) that this brain
tissue is not neurally set to sound but instead to specific
rhythmic-temporal patterns in maximal contrast –crucially, in ~1.5 Hertz
temporal bursts – which are uniquely part of language phonetic-syllabic
structure, which corroborated her earlier infant manual babbling
discoveries and moved beyond “where” language processing occurs in the
human brain to explain the nature of its underlying neural basis.
Petitto’s research has
contributed to the body of knowledge establishing that the signed
languages of Deaf people around the world are real languages with the
full expressive capacity as spoken languages.
 Petitto and colleagues
were also the first to study experimentally the validity of a widely
used educational practice with Deaf children in the 1970s, whereupon
teachers (typically hearing) used parts of ASL signs and linguistic
structure simultaneously while speaking English in the classroom, called
“Total” or “Simultaneous Communication” (or “Simcom”). The Petitto
team’s experimental study of Simcom with Deaf children demonstrated
empirically that it was highly impoverished at representing either ASL
or English (and, in turn, was a non-optimal teaching method), and
instead supported the use of a natural language with Deaf children from
early life (such as ASL), which would best provide a solid linguistic
foundation upon which to learn other languages (such as English) and
advanced the idea that Deaf Education would be best to move closer to a
full bilingual/bicultural educational model. This research had lasting
implications for subsequent Deaf Education policy and practice.
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> Petitto's Education
> Petitto's Lab and New and Current Research
> Research Awards (Select)
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