Naomi Caselli

Assistant Professor

Dr. Naomi Caselli studies how early language experience affects vocabulary acquisition and processing in American Sign Language. She leads an NSF funded project developing ASL-LEX, a database documenting the structure of the American Sign Language lexicon. She has also developed the ASL-CDI, an ASL adaptation of the MacArthur Bates Communicative Development Inventory, that assesses ASL vocabulary in children younger than five. She leads an NIH funded project that uses ASL-LEX and the ASL-CDI to examine how deaf children learn ASL vocabulary, and how delayed exposure to ASL affects vocabulary acquisition.

Find out more about Dr. Caselli’s grant-funded work investigating the relationship between language deprivation and the ASL lexicon on her LexLab website and ASL Vocabulary Acquisition Project site.


PhD in Psychology and Cognitive Science, Tufts University

MA in Psychology, Boston University

EdM in Deaf Education, Boston University

BA in Liberal Arts, The Evergreen State College

Naomi Caselli studies the effects of language deprivation--limited language exposure during early childhood--on language acquisition and development of deaf children. She is particularly interested how people learn and use signs in American Sign Language (ASL). She currently directs three grant funded projects. The first is aimed at developing ASL-LEX, a lexical database for American Sign Language published in Behavior Research Methods. The second is aimed at understanding how the visual modality has shaped the ASL lexicon. The third is aimed at developing ASL vocabulary assessments for young children, and examining the factors that shape early vocabulary acquisition among deaf children who are and are not at risk for language deprivation.

ASL-LEX ( is a lexical database that catalogues information about signs in American Sign Language (Caselli, Sevcikova Sehyr, Cohen-Goldberg, & Emmorey, 2016). It currently includes information about frequency (how often signs are used in everyday conversation), iconicity (how much signs look like what they mean), and phonology (which handshapes, locations, movements etc. are used). Many deaf children in the US unfortunately do not know ASL. Teachers can use ASL-LEX to support vocabulary in deaf and students who are learning ASL (e.g., to develop vocabulary lessons that prioritize commonly used signs). Students can also look up signs based on their sign form, without knowing a sign’s English translation, and begin to learn about linguistic patterns in the forms of signs. It can also be used by ASL researchers to develop experiments. ASL-LEX is also being used to understand how the visual modality has shaped the ASL lexicon. These projects are supported by the National Science Foundation (1625793 and 1749384).

Many deaf children have limited access to language early in life: they often do not have signing role models, and cannot hear the sounds of spoken language. These children are at risk of incomplete acquisition of their first language; this is called language deprivation. My work explores the trajectory of vocabulary development in deaf children with or without language deprivation, because early vocabulary is a critical building block in language acquisition. The goal is to identify the signs that children learn, the factors that promote vocabulary acquisition (Caselli & Pyers, 2017), and to develop assessment tools for identifying children who have limited ASL vocabularies. With these tools in hand, researchers and educators will be better able to develop interventions to mitigate the effects of language deprivation. This project is supported by the National Institute of Deafness and other Communication Disorders (R21DC016104).

Recent Grants/Contracts:

NSF, BCS-1918252 (Role: PI) 2019-2022 "Collaborative Research: Quantifying systematicity, iconicity, and arbitrariness in the American Sign Language Lexicon”

NSF, BCS-1749384 (Role: PI) 2018-2021 "Collaborative Research: Multimethod Investigation of Articulatory and Perceptual Constraints on Natural Language Evolution"

NIH R21 Early Career Research Award DC016104 (Role: PI) 2017-2021 "American Sign Language Vocabulary Acquisition”

NSF, BCS-1625793 (Role: PI) 2016-2020 "The structure of the ASL lexicon: Experimental and statistical evidence from a large lexical database (ASL-LEX)"

Visit Dr. Caselli's Faculty Profile
Visit Dr. Caselli's LexLab Website
Dr. Naomi Caselli awarded NIH grant to research language deprivation in deaf children
Research Update: Dr. Naomi Caselli’s Team Extends Investigation into Language Deprivation in Deaf Children

Caselli, N., Lieberman, A., Pyers, J. (2020). The ASLCDI 2.0: An updated, normed adaptation of the MacArthur Bates Communicative Development Inventory for American Sign Language. Behavior Research Methods.

Hall, M. L., Hall, W. C., Caselli, N. (2019). Deaf children need language, not (just) speech. First Language.

Richardson, H., Koster, Hale, J., Caselli, N., Magid, R., Olson, H., Benedict, R., Pyers, J., and Saxe, R. (2018). Language facilitates theory of mind development: Behavioral and FMRI evidence from individuals with delayed access to language. Nature Communications.

Caselli, N., Pyers, J. (2017). The road to language learning is not entirely iconic: Neighborhood density, iconicity, and frequency facilitate sign language acquisition. Psychological Science.

Caselli, N., Hall, W. C., Lillo-Martin, D. (2017). Operationalization and Measurement of Sign Language. [Letter to the Editor]. Pediatrics.

Caselli, N., Sevcikova Sehyr, Z., Cohen-Goldberg, A., Emmorey, K.  (2016). ASL-LEX: A Lexical Database for American Sign LanguageBehavior Research Methods.

Caselli, N., Caselli, M., Cohen-Goldberg, A. (2015). Inflected words in production: Evidence for a morphologically rich lexicon. Quarterly Journal of Experimental Psychology.

Caselli, N. & Cohen-Goldberg, A. (2014). Lexical access in sign language: A computational model. Frontiers in Psychology, 5.

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