[3] His research has ranged from speech errors and pauses, short-term memory deficits, reading and the dyslexias both in alphabetic scripts and Chinese, and mathematics and dyscalculia.
His early work, following Goldman-Eisler's pioneering studies, explored the functions of pauses in speech.
He went on to show that gestures and glances were also coordinated with planning and with turn-taking in naturally occurring conversations, So, for example, certain gestures—'iconic' gestures— similarly both anticipate lexical selection and resist interruption.
According to the two-route model, the reader simultaneously processes words as a whole and the components of words—letters in alphabetic scripts, and radicals in Chinese.
He showed that the phonic route could be selectively impaired or spared in both learners and neurological patients.
In development, learners who are unable to parse a whole syllable into their component phonemes will have great difficulty learning to read, and will have to rely on recognizing words as a whole, as he was the first to show.
A comprehensive review of research on number abilities in animals made no mention of humans and developmental psychologists ignored the brain.
The central idea is that human numerical abilities are based on an inherited mechanism specialized for extracting numerosity information from the environment.
In his book The Mathematical Brain (1999) he proposed the idea of a 'number module,' an innate, domain-specific mechanism that extracts numerosity from the environment and represents it abstractly, independently of modality and mode of presentation.
This representation is used in an adaptive way, by entering into combinatorial processes isomorphic with arithmetical operations, including =, <, >, +, -, x, etc.
Learners for whom this mechanism is defective or inefficient, will have trouble learning arithmetic, but not necessarily other branches of mathematics.
Brian Butterworth designed an experiment that ran as an interactive exhibit at the Explore-At-Bristol science museum to find whether subitising differed between women and men.
Participants were asked to estimate as fast as they could between one and 10 dots and press the answer on a touch screen.
Language Production Volume 1: Speech and talk Academic Pr ISBN 978-0-12-147501-7 Butterworth B.
Explanations for Language Universals Mouton De Gruyter ISBN 978-3-11-009797-9 Mareschal, D., Butterworth, B., & Tolmie, A.