I am an Assistant Professor at the Leiden Institute of Advanced Computer Science (LIACS) where I co-founded the Creative Intelligence Lab and conduct research at the intersection of language, cognition, cultural evolution and computation. I teach about these topics in the Media Technology MSc program and I currently supervise three PhD students: Ross Towns, Tom Kouwenhoven and Yuchen Lian. On this page you will find information about my background, my research interests and my contact information.

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About me

A little bit of background...


Iconicity and patterns in gesture and sign

This project focuses on the interaction between cognitive biases and learning in creating symbolic representations for tools in gesture and sign. Systematic preferences have been found for the use of different strategies for naming man-made hand-held tools. People tend to either show how you hold it or show what it looks like. Sign languages differ in the relative frequencies of use of these strategies and variations in the choice of strategy seem to be conditioned by meaning and context. With the use of online crowdsourcing platforms we rapidly mapped out initial biases people may have and through laboratory artificial language learning experiments we investigate how these biases interact with pressures from human learning.

Quantifying gesture and sign with Kinect and Deep Learning

The goal of this project is to develop novel methods for analyzing video and depth data capturing human (communicative) behavior. I conducted a first experiment in this domain with Savi Namboodiripad, Ryan Lepic and Dan Lenzen, where we measured changes in gesture as a result of the process of conventionalization with Microsoft Kinect, while participants played a charades-like guessing game. I also worked with Nuno Vasconcelos, head of the Statistical Visual Computing Laboratory (SVCL) at UCSD on machine learning methods for the analysis of sign language data. Most recently my group in Leiden collected new data to look at the emergence of spatial devices in sign languages, again using Kinect.

The emergence of space-time mappings in language

This collaboration studies the emergence of language about time. With Tyler Marghetis and Esther Walker, I designed and implemented experiments in which participants were asked to communicate about concepts of time with a novel, spatial signaling device. Processes like social coordination and transmission resulted in the emergence of patterns. While many results in the field of language evolution suggest that language adapts to the brain, the brain responses of participants in these kinds of experiments has, to the best of our knowledge, never been directly measured. Therefore we teamed up with Seana Coulson, head of the Brain and Cognition Lab (BCL) at UCSD, to investigate the impact of initial bias and social convention on brain responses with EEG.

DIY electronics pet projects

I have always loved making things and besides getting creative with different kinds of arts and crafts I get very excited about DIY electronics projects. As a master's student in Artificial Intelligence I collaborated with a few classmates to build an autonomous robotic blimp, named Zeppy. The project was financially supported by the University of Groningen and the AI department used our robot for promotional activities and special events. At UCSD I brought life and bounciness into a crocheted purple penguin bird, a dancing robot, with Eric Leonardis.

Live exhibits

I love designing outreach projects to bring scientific experiments and lectures to non-academic communities. It started with an interactive Science Live exhibition in Science Center Nemo in 2012 when my experiment ran for 2 weeks at the museum. Since then, my studies appeared at the ‘Discovery festival’ in Amsterdam, the Science Museum Utrecht, the ‘Nacht van Kunst en Kennis’ in Leiden and various festivals in California where I became part of 'BrainScratch', a collective of thinkers, makers, artists and communicators who create immersive experiences related to complex systems. By creating interactive interfaces, I collect real data with event visitors as participants, give talks and engage in conversations about science one-on-one. Most recently, I participated in Lowlands Science (2019), a competitive program organized by one of the biggest music festivals in the Netherlands

Combinatorial structure in artificial whistled languages

My PhD research was on the emergence of structure in speech. I worked with computer models to run language evolution simulations and I developed innovative experimental methods for studying the evolution of combinatorial structure with human participants. In my experiments, people learned and produced artificial languages that were produced with a slide whistle. One of the main aims was to investigate to what extent structures in sound systems for speech can be explained as the result of general cognitive biases and the process of cultural transmission.


Selected list of published work

Check my Google Scholar page for a more complete list

  • Lian, Y., Bisazza, A., & Verhoef, T. (2021) The Effect of Efficient Messaging and Input Variability on Neural-Agent Iterated Language Learning. In Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing (pp. 10121–10129) Association for Computational Linguistics.

  • Verhoef, T., & Ravignani, A. (2021) Melodic universals emerge or are sustained through cultural evolution. Frontiers in Psychology, 12, 668300

  • Hofer, M., Verhoef, T. & Levy, R. (2020) Hierarchical Inferences Support Systematicity in the Lexicon. Proceedings of the 42nd Annual Conference of the Cognitive Science Society. (pp. 2398-2403). Cognitive Science Society.

  • Verhoef, T. & Lepic, R. (2020) Gestural Origins of Verb and Noun Encoding in Sign Language Emergence. The Evolution of Language: Proceedings of the 13th International Conference (EvoLang13). doi:10.17617/2.3190925.

  • Towns, R., Gómez-Maureira, M. A., Sommer, K., van Duijn, M. & Verhoef, T. (2020) The Evolution of Spatial Devices in Gestural Storytelling. The Evolution of Language: Proceedings of the 13th International Conference (EvoLang13). doi:10.17617/2.3190925.

  • Bragg, D., Koller, O., Bellard, M., Berke, L., Boudreault, P., Braffort, A., Caselli, N., Huenerfauth, M., Kacorri, H., Verhoef, T., Vogler, C. and Morris, M. (2019) Sign Language Recognition, Generation, and Translation: An Interdisciplinary Perspective. In Proceedings of the 21st International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS) (pp. 16-31) Pittsburgh, PA, USA

  • Verhoef, T., Walker, E., Marghetis, T. & Coulson, S. (2018) Neural measures of sensitivity to a culturally evolved space-time language: shared biases and conventionalization. In: Proceedings of the 40th Annual Conference of the Cognitive Science Society (pp. 1151-1156) Austin, TX: Cognitive Science Society.

  • Verhoef, T., Walker, E. & Marghetis, T. (2018) Cognitive biases and cultural evolution in the emergence of space-time mappings in language. The Evolution of Language: Proceedings of the 12th International Conference, doi:10.12775/3991-1.127

  • Ravignani, A. & Verhoef, T. (2018) Which melodic universals emerge from repeated signaling games. Artificial Life, 24(2), 149-153

  • de Boer, B. & Verhoef, T. (2018) Evolution of Speech. In The Oxford Handbook of Psycholinguistics (pp. 841-864). Oxford University press.

  • Roberts, S. G., & Verhoef, T. (2016) Double-blind reviewing at EvoLang 11 reveals gender bias. The Journal of Language Evolution, 1(2), 163-167.

  • Namboodiripad, S., Lenzen, D., Lepic, R. & Verhoef, T. (2016) Measuring conventionalization in the manual modality. The Journal of Language Evolution 1(2), 109-118.

  • Verhoef, T., Walker, E. & Marghetis, T. (2016) Cognitive biases and social coordination in the emergence of temporal language. Proceedings of the 38th Annual Conference of the Cognitive Science Society. (pp. 2615-2620) Austin,TX: Cognitive Science Society.

  • Verhoef, T., Padden, C. & Kirby, S. (2016) Iconicity, Naturalness and Systematicity in the Emergence of Sign Language Structure. The Evolution of Language: Proceedings of the 11th International Conference (EVOLANG11)

  • Verhoef, T., Kirby, S. & de Boer, B. (2015) Iconicity and the Emergence of Combinatorial Structure in Language. Cognitive Science. pp. 1–26.

  • Verhoef, T., Roberts, S. G. & Dingemanse, M. (2015) Emergence of systematic iconicity: Transmission, interaction and analogy. Proceedings of the 37th Annual Conference of the Cognitive Science Society. (pp. 2481-2486) Austin,TX: Cognitive Science Society.

  • Verhoef, T., Kirby, S. & de Boer, B. (2014) Emergence of combinatorial structure and economy through iterated learning with continuous acoustic signals. Journal of Phonetics 43C, pp. 57-68

  • Verhoef, T. & de Boer, B. (2014) Iterated learning of sound systems and the emergence of tone categories. In The evolution of language: Proceedings of the 10th international conference (evolangX). (pp. 545-546). Hackensack NJ: World Scientific.

  • Verhoef, T. (2014) Cultural evolution, compression and the brain. In The Past, Present and Future of Language Evolution Research (pp. 22-30).

  • Verhoef, T. (2013) Efficient coding in speech sounds: Cultural evolution and the emergence of structure in artificial languages. PhD Thesis, University of Amsterdam

  • Verhoef, T. , Kirby, S. & de Boer, B. (2013) Combinatorial structure and iconicity in artificial whistled languages. In M. Knauff, M. Pauen, N. Sebanz, & I. Wachsmuth (Eds.), Proceedings of the 35th Annual Conference of the Cognitive Science Society (pp. 3669-3674) Austin, TX: Cognitive Science Society.

  • Verhoef, T. (2012) The origins of duality of patterning in artificial whistled languages. Language and Cognition 4(4), 357-380.

  • Verhoef, T., de Boer, B., & Kirby, S. (2012) Holistic or synthetic protolanguage: Evidence from iterated learning of whistled signals. In The evolution of language: Proceedings of the 8th international conference (evolang8). (pp. 386-375). Hackensack NJ: World Scientific.

  • de Boer, B. & Verhoef, T. (2012) Language Dynamics in Structured Form and Meaning Spaces, Advances in Complex Systems 15(3),1150021-1–1150021-20

  • Verhoef, T., Kirby, S. & Padden, C. (2011) Cultural emergence of combinatorial structure in an artificial whistled language. In L. Carlson, C. Hölscher & T. Shipley (Eds.), Proceedings of the 33rd Annual Conference of the Cognitive Science Society (pp. 483-488). Austin, TX: Cognitive Science Society.

  • Verhoef, T. & de Boer, B.G. (2011) Cultural emergence of feature economy in an artificial whistled language. In E. Zee & W. Lee (Eds.), Proceedings of the 17th International Congress of Phonetic Sciences (pp. 2066-2069). Hong Kong: City University of Hong Kong.

  • Verhoef, T. & Boer, B.G. de (2011). Language acquisition age effects and their role in the preservation and change of communication systems. Linguistics in Amsterdam, 4(1), 1-23.

  • Verhoef, T. & de Boer, B. (2010) The critical period and preservation of emerged vowel systems, In: Smith, A. D. M., Schouwstra, M., de Boer, B. & Smith, K. (Eds.) The Evolution of Language, Proceedings of the 8th International Conference (evolang8) (pp. 509–510 ) New Jersey: World Scientific