Molly Flaherty
Research program
In my research I investigate how the human mind shapes language, and how language environment shapes the human mind.
I seek to better understand the developing human mind by closely examining the structure of language. My work explores the emergence of linguistic structure in one of the youngest languages known to science: Nicaraguan Sign Language (NSL). NSL was born in Managua about 35 years ago with the opening of the first school for deaf children. By examining and comparing the signing of different generations of signers today, we have the rare chance to watch the changes a new language undergoes as it is born. Additionally, I study the raw materials from which this new language was created: homesign. Homesign systems are gestural systems created by isolated deaf individuals to communicate with family and friends.
I also seek to recreate the conditions of natural language emergence inside the laboratory. New languages like NSL are singularly informative in terms of understanding how new languages are born, but because they grow in the complex real world, it is difficult to assess the relative contributions of individual factors when it comes to building a language. By replicating these conditions in the lab, we gain experimental control over factors of interest. By looking both at natural language emergence in the world and simulated language emergence in the laboratory, we can better understand the creation of new language by human minds.
In my newest research, I investigate child language learning in a wide range of early language environments. I seek to better understand when typical language learning parallels language emergence, and when it does not.
I also study the effects of one’s early linguistic environment on cognition. Language acquisition is thought to be key for normal cognitive development in many areas, but only a situation like that found in Nicaragua provides the opportunity to test that hypothesis.
Publications
Yu, Y., Barner, D., … Flaherty, M., et al. (2026). ManyNumbers 3: A Multi‐Lab Study of Demographic Correlates of Early Number Knowledge. Registered Report. Developmental Science, 29(3), e70184. https://doi.org/10.1111/desc.70184
Coppola, M. Flaherty, M., Gagne, D., Gagne, K., Kocab, A., Martin, A., Morales Blanco, D., Morales Ruíz I., Pyers, J., Senghas, A. (2025) How Nicaraguan signing has been shaped by vertical transmission and horizontal interaction: Evidence from the mergence and convergence of linguistic elements. Sign Language Studies 26(1): 69-103. https://doi.org/10.1353/sls.2025.a981200
Flaherty, M., Schouwstra, M. (2025). Validating lab studies of silent gesture with a naturally emerging sign language: How order is used to describe intensional vs. extensional events in Nicaraguan Sign Language. Topics in Cognitive Science. https://doi.org/10.1111/tops.12751
Cuskley, C., Woods, R., Flaherty, M. (2024). The limitations of Large Language Models (LLMs) for understanding human language and cognition. Open Mind: Discoveries in Cognitive Science, 8: 1058–1083. https://doi.org/10.1162/opmi_a_00160
Flaherty, M., Sato, A.**, Kirby, S. (2023). Quantifying the emergence of structure in Nicaraguan Sign Language with motion tracking technology. Cognitive Science. http://doi.org/10.1111/cogs.13277
Motamedi, Y.*, Montemurro, K.**, Abner, N., Flaherty, M., Kirby, S. Goldin-Meadow, S. (2022). The seeds of the noun-verb distinction in the manual modality: improvisation and interaction in the emergence of grammatical categories. Languages. https://doi.org/10.3390/languages7020095
Sato, A.**, Kirby S., Flaherty, M. (2022). Language emergence can take multiple paths: Using motion capture to track axis use in Nicaraguan Sign Language. Glossa, 7(1). doi: https://doi.org/10.16995/glossa.6151
Flaherty, M., Hunsicker, D., Goldin-Meadow, S. (2021). Structural biases that children bring to language learning: A cross-cultural look at gestural input to homesign. Cognition, 211, 104608.
Rissman, L., Horton, L., Flaherty, M., Senghas, A., Coppola, M., Brentari, D., Goldin-Meadow, S. (2020) Emergence of agent-backgrounding in homesign and Nicaraguan Sign Language. Cognition, 203, 104332.
Sato, A.*, Schouwstra, M., Flaherty, M., Kirby, S. (2020) Do all aspects of learning benefit from iconicity? Evidence from motion capture. Language and Cognition. Advance online publication. Language and Cognition, 12(1), 36-55. doi:10.1017/langcog.2019.37
Abner, N., Flaherty, M., Stangl, K.*, Coppola, M., Goldin-Meadow, S. (2019). Nouns and verbs: The Emergence of overt morphological marking in Nicaraguan Sign Language. Language, 95(2), 230-267.
Gleitman, L. Senghas A., Flaherty, M., Coppola, M., Goldin-Meadow, S. (2019) The emergence of the formal category “symmetry” in a new sign language. Proceedings of the National Academy of Sciences of the USA, 116(24), 11705-11711.
Flaherty, M., Stangl, K.*, Goldin-Meadow, S. (2016) Do Lab Attested Biases Predict the Structure of a New Natural Language? In S. Roberts, C. Cuskley, L. Barceló-Coblijn, O. Feher, & T. Verhoef, (Eds.), Proceedings of the Eleventh Evolution of Language Conference. Singapore: World Scientific Publishing Co.
Flaherty, M., Goldin-Meadow, S. (2014) Language from Gesture?: Emergent Transitivity Marking in Nicaraguan Sign Language. In E. Cartmill, S. Roberts, H. Lyn, & H. Cornish, (Eds.), Proceedings of the Tenth Evolution of Language Conference. Singapore: World Scientific Publishing Co.
Spaepen, E., Coppola, M., Flaherty, M., Spelke, E., Goldin-Meadow, S. (2013). Generating a lexicon without a language model: Do gestures for number count? Journal of Memory and Language, 69(4), 496-505.
Flaherty, M., Senghas, A. (2011). Numerosity and number signs in deaf Nicaraguan adults. Cognition, 121(3), 427-436.
Flaherty, M. (2010). Review of Sign Language Acquisition. Journal of Child Language. 37, 956-961.
Flaherty, M., Goldin-Meadow, S. (2010) Does input matter? Homesign in Nicaragua, China, Turkey and the USA. In A.D.M. Smith, M. Schouwstra, B. de Boer, & K. Smith, (Eds.), Proceedings of the Eighth Evolution of Language Conference (pp. 403–404). Singapore: World Scientific Publishing Co.
Hurford, J. R., Flaherty, M., Argyropoulos, G. (2007). Past and future, human and non-human, semantic/procedural and episodic, commentary on Suddendorf and Corballis: The evolution of foresight: What is mental time travel and is it unique to humans? Behavioral and Brain Sciences, 30, 324-325.
* indicates undergraduate student author
**indicates graduate student author
Press
The Measure of Everyday Life - Dr. Flaherty was interviewed about her research for this RTI International/WNCU Public Radio program. Audio and transcript are available at this link.
Congrats! It's a Language! Dr. Flaherty was interviewed about her work on Nicaragua Sign for this Duolingo Podcast.
The New Yorker - Dr. Flaherty provided her perspective on the creation of a new tactile language.
The World - Dr. Flaherty was interviewed for this PRI/National Public Radio Program.
Subtitle Podcast - Dr. Flaherty was interviewed about Nicaraguan Sign for this podcast sponsored by the Linguistic Society of America (LSA). Audio and transcript are available at this link.