The interaction between cognitive ease and informativeness shapes the lexicons of natural languages (2022)

Abstract: It is common for languages to express multiple meanings with the same word, a phenomenon known as colexification. For instance, the meanings FINGER and TOE colexify in the word “dedo” in Spanish, while they do not colexify in English. Colexification has been suggested to follow universal constraints. In particular, previous work has shown that related meanings are more prone to colexify. This tendency has been explained in terms of the cognitive pressure for ease, since expressing related meanings with the same word makes lexicons easier to learn and use. The present study examines the interplay between this pressure and a competing universal constraint, the functional pressure for languages to maximize informativeness. We hypothesize that meanings are more likely to colexify if they are related (fostering ease), but not so related as to become confusable and cause misunderstandings (fostering informativeness). We find support for this principle in data from over 1200 languages and 1400 meanings. Our results thus suggest that universal principles shape the lexicons of natural languages. More broadly, they contribute to the growing body of evidence suggesting that languages evolve to strike a balance between competing functional and cognitive pressures.

## introduction across languages, it is common for words to be associated with multiple meanings. moreover, certain meanings are expressed by the same form more often than others @xcite . for instance, the colexification -i.e., the conventional association of multiple meanings with the same form-of toe and finger is found in at least 135 languages @xcite . these languages are spoken throughout the world and span multiple unrelated language families. recent research suggests that semantic relatedness increases colexification likelihood @xcite . semantic memory may favor colexifying meanings that are easy to relate to one another. this, in turn, may aid vocabulary acquisition, lexical retrieval and interpretation. building on these findings, we investigate the interplay between this and another major force: pressure for the lexicon to be informative, in the sense of supporting accurate information transfer (e.g., @xcite . we hypothesize that languages strike a balance between these two forces. in particular, we expect colexification likelihood to increase with semantic relatedness, until a point is reached at which meanings are too related; for these highly related meanings, we expect pressure for informativeness to counteract the increasing trend, because these meanings would not be easy to disambiguate even in context. we find support for this hypothesis in two large scale analyses. foot_0 ## analysis 1 to study the relationship between semantic relatedness and colexification, we fit three generalized additive logistic models to colexification data spanning over 1200 languages and more than 1400 meanings, totaling 203056 data points. this data comes from clics 3 @xcite , the largest cross-linguistic database of colexifications available to date. the models characterize how likely a pair of meanings is to colexify in a given language as a function of one of three data-induced estimates of relatedness: distributional similarity, using pre-trained embeddings @xcite ; associativity data @xcite ; and the first principal component of these two measures (pc1). both distributional and associative information are based on dutch and english glosses of the meanings found in clics 3 ; that is, dutch and english words are used as surrogates for meanings to estimate the latter's relatedness. since language contact and common linguistic ancestry influence colexification @xcite , the models are also passed information about how often a pair of meanings colexifies in other languages. this information is weighted by the phylogenetic/geographic distance to the response language. an indicator codifies whether a relatedness estimate stems from dutch or english data. model comparison using approximate leave-oneout cross-validation suggests that pc1 is the best predictor of colexification, with a difference of -715 in expected log pointwise predictive density to the second highest ranked model. figure 1 shows its estimated marginal effects. these results largely support to our hypothesis: colexification increases with relatedness until meanings are "too related", which makes their colexification decrease. note, however, that the data are also consistent with a plateau rather than a decrease for highly related meanings (see shaded area in the figure). this is still consistent with the main hypothesisinformativeness counteracting simplicity for highly related meanings-, with a smaller effect of informativeness than we had expected. ## analysis 2 our hypothesis specifically predicts that the decrease in colexification likelihood for highly related meanings is due to their confusability. we next probe confusability more directly, focusing on the kind of relationship meanings stand in. pressure for informativeness should make colexifying opposites (e.g., left and right) less likely than colexifying meanings in other kinds of relationships. opposite meanings express contrasts, being maximally similar in every respect but one (e.g., @xcite . therefore, losing the distinction they encode can be expected to be particularly harmful in communicative terms. we compare opposites to meaning pairs standing in two semantic relations that do not necessarily lead to high confusability: part-whole (e.g., toe-foot) and subsumption (e.g., calf-cattle). colexification rates were estimated from 1416 meanings and 2279 languages from clics 3 . semantic relations are from wordnet @xcite , using english words as proxies for meanings. pairs in none of the three relations were classified as 'none/other'. as expected, this group has the lowest mean percentage of colexification (0.06, with a 95% ci of [0.06, 0.06]), followed by opposites (1.4 [1.3, 1.5]), then by subsumption (3.1 [3.0, 3.3]) and part-whole pairs (3.7 [3.5, 3.8]). these results suggest, first, that standing in one of the three relations increases the odds for meanings to colexify compared to 'none/other'; and second, that not all relations are equally conducive to colexification, with opposites being less likely to colexify. we thus again find that relatedness makes colexification more likely, but that the need to distinguish confusable meanings can counteract this trend. under our interpretation, simplicity makes colexification likelihood for opposites increase, whereas informativeness makes them decrease, resulting in their position in the middle compared to the other relations. ## conclusions a growing body of research supports the idea that languages are efficient in the sense that they strike a good balance between informativeness and simplicity (e.g., @xcite . our large scale analyses suggest such a balance in the lexicon. we find that colexification likelihood increases with semantic relatedness, until an inflection point is reached, after which it decreases or flattens out (analysis 1). this shift may be a consequence of a need for meanings to be distinguishable in context (analysis 2).