Ambiguity has often been viewed as a hindrance to communi-cation. In contrast, Piantadosi et al. (2012) argued that ambi-guity may be useful in that it allows communication to be ef-ficient, and they found support for this argument in the spokenforms of modern English, Dutch, and German. The historicalorigins of this phenomenon cannot be probed in the case of spo-ken language, but they can for written language, as it leaves anenduring trace. Here, we explore ambiguity and efficiency inone of the earliest known written forms of language: Sumeriancuneiform. Sumerian cuneiform exhibits extensive ambiguity,and for that reason it has been considered to be poorly suited forcommunication. We find, however, that ambiguity in Sumeriancuneiform supports efficient communication, mirroring the ear-lier findings for spoken English, Dutch, and German. Thus, theearly stages of human writing exhibit evidence suggesting pres-sure for communicative efficiency.

It has long been noted that the best examples, or foci, ofcolor categories tend to align across diverse languages (Berlin& Kay, 1969)—but there is limited documentation of suchuniversal foci in other semantic domains. Here, we explorewhether spatial topological categories, such as “in” and “on”in English, have focal members comparable to those in color.We document names and best examples of topological spatialrelations in Dutch, English, French, Japanese, Korean, Man-darin Chinese, and Spanish, and find substantial consensus,both within and across languages, on the best examples of suchspatial categories. Our results provide empirical evidence forfocal best examples in the spatial domain and contribute fur-ther support for a theory of “natural concepts” in this domain.Keywords: Language and thought; spatial cognition; cate-gories; semantic universals.The central role of fociFor decades, discussions of natural language categories suchas “dog” or “blue” have emphasized prototypes, family re-semblance, and fuzzy sets—all notions specifying relationsbetween central cases and boundaries, and recognizing gra-dation in category membership. An especially well-studiedand debated case is that of focal colors, or best examplesof color categories (e.g. Berlin & Kay, 1969; Heider, 1972;Kay & McDaniel, 1978; Roberson et al., 2000; Regier etal., 2005; Abbott et al., 2016). Despite the ongoing debate,there is broad consensus that such best examples of color cat-egories often (but not always) align across languages, andthat languages sometimes have composite categories appar-ently organized around multiple foci—for example a com-posite green-blue or “grue” category.Despite the attention given to focal colors, studies of cate-gorization and semantic typology in many other semantic do-mains have not emphasized category best examples as promi-nently, but have instead tended to characterize categories assets, such that an exemplar may simply be a member of thecategory or not. Within the domain of spatial topological re-lations, previous work has drawn on extensional patterns innaming as evidence for central exemplars and core meaningsof categories like “in” and “on” (e.g., Levinson et al., 2003;Johannes, Wang, Papafragou, & Landau, 2015; Johannes,Wilson, & Landau, 2016; Landau, Johannes, Skordos, & Pa-pafragou, 2017), but without directly querying speakers aboutbest examples per se. Here, we employ empirical best ex-ample data to provide a long-overdue response to a call byFeist (2000: 236) to determine whether spatial relational cat-egories, like colors, have focal members.In what follows, we review key findings on focal colorsand their relationship to color category semantics. We thendescribe parallels to color in the domain of spatial topologicalrelations, and summarize an account (Levinson et al., 2003)of focal spatial relations that was developed and evaluatedon the basis of spatial naming data, but without groundingin empirical best examples. We then present our study, whichreexamines the hypotheses of this previous account using em-pirical best example data from seven languages. We explore