Language as a Cognitive Technology: English-Speakers Match Like Pirahã When You Don't Let Them Count

Language as a Cognitive Technology: English-Speakers Match Like Pirah˜a When You Don’t Let Them Count Michael C. Frank, Evelina Fedorenko, and Edward Gibson {mcfrank, evelina9, egibson}@mit.edu Department of Brain and Cognitive Sciences, 43 Vassar Street Cambridge, MA 02139 USA Abstract To support this hypothesis, we first discuss numerical cognition, a case study of language and conceptual change (Carey & Spelke, 1994) which has been studied across a vari- ety of populations. In particular, we focus on the finding that the Pirah˜a—an Amazonian hunter-gatherer group who lack words for exact numbers, are able to perform simple one-to- one matching tasks but unable to perform numerical tasks that require remembering exact quantities (Everett, 2005; Frank et al., in press; Gordon, 2004). Here we present experimen- tal data showing the same pattern of performance in Amer- ican participants who performed these matching tasks while simultaneously engaged in verbal shadowing. We then dis- cuss these data in light of results from several other domains. The Pirah˜a, an Amazonian hunter-gatherer tribe, lack words for numbers and are unable to complete simple matching tasks when the tasks require memory for exact quantities (Gordon, 2004; Frank et al., in press). Here we show that American par- ticipants perform similarly to the Pirah˜a when asked to execute the same kinds of matching tasks under verbal interference. These results provide support for the hypothesis that number words act as a “cognitive technology”: a method for quickly and efficiently storing information via abstraction. We review a variety of other evidence supporting this proposal from the domains of color, navigation, and theory of mind. Keywords: Numerical cognition; verbal interference; lan- guage and thought; Whorf hypothesis; Pirah˜a. Introduction Numerical cognition in infants and non-human primates is thought to be subserved by two distinct systems (Feigenson et al., 2004). The parallel-individuation (“object file”) system is related to visual attention and object tracking and is used to track the identity of small numbers of discrete objects. In con- trast, the analog magnitude system is used to represent large, approximate quantities and can operate over arbitrarily large quantities. Parallel individuation is precise but only functions for quantities below three or four; in contrast, analog mag- nitude estimation exhibits a constant coefficient of variation (error relative to the size of the set being estimated) (Whalen et al., 1999). How does knowing a language affect the way you are able to perceive, act and reason in the world? Do the differences be- tween languages cause systematic differences in the cognition of their speakers? These questions about the relationship be- tween language and thought have been among the most con- troversial in cognitive science for many years. However, re- cent evidence from non-linguistic and cross-cultural popula- tions has given some insight into this relationship in domains such as number, color, navigation, and theory of mind. In this paper, we propose a unifying account of these strands of evidence, which we call the “cognitive technology” hypothesis (Dascal, 2002; Frank et al., in press): The relationship between a lack of number language and reliance on these core, pre-linguistic numerical systems was first documented via case studies of two Amazonian groups, the Pirah˜a (Gordon, 2004) and the Munduruk´u (Pica et al., 2004). The Pirah˜a presented a particularly interesting case: their language was reported to have words roughly corre- sponding to the concepts of “one,” “two,” and “many”, and they were unable to perform a variety of simple matching tasks. Gordon interpreted these results as providing evidence for a strong Whorfian claim: that without language for num- ber, the Pirah˜a had no notion of exact quantity and were thus unable even to put objects in one-to-one correspondence. Rather than altering underlying representations, lan- guages instead help their speakers accomplish difficult or intractable cognitive tasks by providing abstractions which allow for the efficient storage and processing of informa- tion. This hypothesis synthesizes a number of existing theoretical ideas. Vygotsky (1986) suggested that language could be a scaffold for action by providing external support for difficult tasks. Similarly, several authors have suggested that language works to code experience and that Whorfian effects stem from differences in the way experience is coded (Hunt & Agnoli, 1991), or that language augments cognition by providing an external resource for information storage and transformation (Clark, 1998). While these proposals are deeply related to our own, we believe that the contribution of the view here is to synthesize these ideas into an account in which the role of lan- guage as a tool for abstraction explains a number of recently identified “Whorfian” effects, while still acknowledging the existence of core cognitive abilities which are unaltered by language (Spelke & Kinzler, 2007; Carruthers, 2002). In recent work (Frank et al., in press), we provided evi- dence that Pirah˜a in fact has no words for exact quantities whatsoever; the previously reported numerical terms appear to be comparative or relative terms. In addition, we showed that—contra Gordon (2004)—the Pirah˜a succeeded in sim- ple one-to-one matching tasks, suggesting that the concept of exact quantity (the idea that adding or subtracting one object makes a difference) does not depend on linguistic knowledge. However, we replicated Gordon’s results that the Pirah˜a had