The image below shows the eye-movement fixation patterns of four age groups--adults, and three-, six-, and nine-month-old infants--as they watched a short clip of "A Charlie Brown Christmas." See if you can guess which is which. Infants' interest in different aspects of complex videos tells us about their developing social knowledge and attentional abilities, two parts of cognition that will play an important role as they begin the process of language learning.
How do children learn to use and understand language? Each aspect of language acquisition--from learning sound categories to learning syntactic rules--is a difficult computational challenge. We are interested in characterizing the nature of the computations underlying language learning, particularly how this process interacts with and makes use of social and conceptual knowledge. We study problems like finding the boundaries between words (word segmentation) and mapping words to concepts (word learning) in order to understand how learning mechanisms interact with the rich variety of information available in learners' social and physical environment. Our investigations use a wide variety of methods, including infant eye-tracking, naturalistic observation and corpus work, behavioral experiments with preschool and school-aged children and adults, web-based experimentation, and computational modeling.
What is the relationship between the language you speak, the culture you live in, and the way you think about the world? We study this fascinating set of inter-related questions via cross-cultural work using number and mathematics as a case study of how language, concepts, and culture intertwine. Number is an important case study of these kinds of issues because it is so fundamental to life in Western, industrialized nations. However, there is wide variance in the kinds of number systems that are used across the world. For example, we have examined the numerical cognition of the Pirahã, a tribe of indigenous people living in Amazonas, Brazil who have no words for numbers. We are also currently investigating the numerical cognition of "mental abacus" experts, who picture an abacus and imagine manipulating the beads in their heads to perform astonishing arithmetic feats.
Rather than using any particular method, our approach is to make use of a broad variety of different approaches to the same questions: experimental, observational, and computational. As usual, Roger Brown said it best:
We would like to express the distaste experimentalists must feel for the assumptions, compromises, and qualifications involved in the use of naturalistic data. We find that naturalistic studies build an appetite for experiment - for controls, complete data, large samples, and statistical analysis. But we also find the reverse. The two kinds of research are complementary activities and complementary forms of evidence. In experimental work one uses the ingenuity he has on advance planning for data collection, whereas in naturalistic work little ingenuity goes into the data collection and all that is available goes into data analysis. The history of psychology generally and of psycholinguistics in particular shows that careful experimental work provides no sure path to the truth. Neither does naturalism. There are rich opportunities for error in either method. But on the whole, the opportunities arise at different points, and when the methods are used in combination, the truth has a chance to appear. (Brown and Hanlon, 1970)