Syntactic chunking reveals a core syntactic representation of multi-digit numbers, which is generative and automatic

Abstract

Representing the base-10 structure of numbers is a challenging cognitive ability, unique to humans, but it is yet unknown how precisely this is done. Here, we examined whether and how literate adults represent a number’s full syntactic structure. In 5 experiments, participants repeated number-word sequences and we systematically varied the order of words within each sequence. Repetition on grammatical sequences (e.g., two hundred ninety-seven) was better than on non-grammatical ones (hundred seven two ninety). We conclude that the participants represented the number’s full syntactic structure and used it to merge number words into chunks in short-term memory. Accuracy monotonously improved for sequences with increasingly longer grammatical segments, up to a limit of ~ 4 words per segment, irrespectively of the number of digits, and worsened thereafter. Namely, short chunks improved memorization, whereas oversized chunks disrupted memorization. This chunk size limit suggests that the chunks are not based on predefined structures, whose size limit is not expected to be so low, but are created ad hoc by a generative process, such as the hierarchical syntactic representation hypothesized in Michael McCloskey’s number-processing model. Chunking occurred even when it disrupted performance, as in the oversized chunks, and even when external cues for chunking were controlled for or were removed. We conclude that the above generative process operates automatically rather than voluntarily. To date, this is the most detailed account of the core representation of the syntactic structure of numbers—a critical aspect of numerical literacy and of the ability to read and write numbers.

Syntax-driven number reading: The identification of digits is dominated by the number’s syntactic structure

“…For example, the number 234,567 would be represented as [2 & (3 & 4)] & [5 & (6 & 7)]. A recent study support the idea that numbers are indeed represented in a hierarchical manner, at least when the task involves verbal numbers (Barash & Dotan, 2019; also see Dotan & Brutman, 2022). The existence of a syntactic hierarchy when processing verbal numbers fits well with the wellestablished idea that humans represent linguistic-verbal information using tree-like hierarchical representations (Chomsky, 1956(Chomsky, , 1995.…”

Correction: Syntactic chunking reveals a core syntactic representation of multi-digit numbers, which is generative and automatic

“…The original article Dotan and Brutman ( 2022 ) contained an error in co-author, Nadin Brutmann’s name which has since been corrected.…”

A pure syntax of multi-digit numbers in the absence of lexicon and semantics

“…;Moura et al, 2013;Power & Dal Martello, 1990. Some syntactic processes handle highly specific aspects of syntax -e.g., the order of digits, the positions of the digits 0 and 1 (which have special syntactic importance), how many digits a number has, and the specific lexical class (ones, tens, teens) of each number word (Cohen et al, 1997;Cohen & Dehaene, 1991;Dotan, Eliahou, et al, 2021;Dotan & Friedmann, 2018;McCloskey et al, 1986; see review in Dotan & Brutmann, 2022). Critically, on top of these lowlevel syntactic processes, there exists a core representation of the number's full syntactic structure (Dotan, Breslavskiy, et al, 2021;Dotan & Brutmann, 2022;Friedmann et al, 2021;McCloskey et al, 1986).…”

“…Some syntactic processes handle highly specific aspects of syntax -e.g., the order of digits, the positions of the digits 0 and 1 (which have special syntactic importance), how many digits a number has, and the specific lexical class (ones, tens, teens) of each number word (Cohen et al, 1997;Cohen & Dehaene, 1991;Dotan, Eliahou, et al, 2021;Dotan & Friedmann, 2018;McCloskey et al, 1986; see review in Dotan & Brutmann, 2022). Critically, on top of these lowlevel syntactic processes, there exists a core representation of the number's full syntactic structure (Dotan, Breslavskiy, et al, 2021;Dotan & Brutmann, 2022;Friedmann et al, 2021;McCloskey et al, 1986). This representation, which is hypothesized to parallel the syntactic representation of sentences in language (Barash & Dotan, 2019), mediates several number-processing tasks (even if not all, Campbell & Clark, 1992;Cohen & Dehaene, 1991, 2000González & Kolers, 1982;Noël & Seron, 1997).…”

“…First, I aimed to corroborate the existence of a core syntactic representation. In particular, I aimed to rule out the possibility that the previous evidence for its existence (Dotan, Breslavskiy, et al, 2021;Dotan & Brutmann, 2022;Friedmann et al, 2021) was confounded by a semantic representation, which unavoidably exists in tasks involving numbers. The second goal was to arbitrate between two views about the relation between the core syntax and the semantics of multi-digit numbers.…”