Degree and not type of iconicity affects sign language vocabulary acquisition

Abstract

Lexical iconicity-signs or words that resemble their meaning-is overrepresented in children's early vocabularies. Embodied theories of language acquisition predict that symbols are more learnable when they are grounded in a child's firsthand experiences. As such, pantomimic iconic signs, which use the signer's body to represent a body, might be more readily learned than other types of iconic signs. Alternatively, the structure mapping theory of iconicity predicts that learners are sensitive to the amount of overlap between form and meaning. In this exploratory study of early vocabulary development in American Sign Language (ASL), we asked whether type of iconicity predicts sign acquisition above and beyond degree of iconicity. We also controlled for concreteness and relevance to babies, two possible confounding factors. Highly concrete referents and concepts that are germane to babies may be amenable to iconic mappings. We reanalyzed a previously published set of ASL Communicative Development Inventory (CDI) reports from 58 deaf children learning ASL from their deaf parents (Anderson & Reilly, 2002). Pantomimic signs were more iconic than other types of iconic signs (perceptual, both pantomimic and perceptual, or arbitrary), but type of iconicity had no effect on acquisition. Children may not make use of the special status of pantomimic elements of signs. Their vocabularies are, however, shaped by degree of iconicity, which aligns with a structure mapping theory of iconicity, though other explanations are also compatible (e.g., iconicity in child-directed signing). Previously demonstrated effects of type of iconicity may be an artifact of the increased degree of iconicity among pantomimic signs. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Figure 1

The concept “frog” is concrete, but the sign FROG is not iconic.

Figure 2

The signs BABY, BUTTERFLY, and GLASSES from left to right. The sign BABY was considered pantomimic because it is mimics how the arms hold a baby. The sign BUTTERFLY was considered perceptual because the hands are used to depict the wings of a butterfly. The sign GLASSES was considered both pantomimic and perceptual because the hand is used to depict the shape of the lens, and place of articulation (the eye) is also where glasses are worn.

Figure 3

The relationships between degree of iconicity, type of iconicity, babiness, and concreteness. On the right, the grey shapes in the violin plots indicate the density of the distribution of each type of iconic sign. The hinges of the boxplots indicate the 25^th and 75 percentiles, and the whiskers indicate 1.5 times the interquartile range. Note that for the sake of readability only a subset of items were labeled here. The labels are English glosses from ASLLEX. Videos of each sign can be found at http://asl-lex.org/. Figures were plotted using the library ggplot2 (Wickham, 2016), and the geom_flat_violin function (Robinson, 2015).

Figure 4

The percentage of children who have acquired each sign as a function of the sign’s type of iconicity. The grey shapes indicate the density of the distribution. The hinges of the boxplots indicate the 25^th and 75 percentiles, and the whiskers indicate 1.5 times the interquartile range. Note that for the sake of readability only a subset of items were labeled here. The labels are English glosses from ASL-LEX. Videos of each sign can be found at http://asl-lex.org/ Figures were plotted using the library ggplot2 (Wickham, 2016), and the geom_flat_violin function (Robinson, 2015).

Figure 5

Observed versus randomly generated estimates of proportion of pantomimic signs, degree of iconicity, concreteness, and babiness. Red bars indicate the 5^th and 95^th percentile of the proportion (pantomimic signs) or average (iconicity degree, concreteness, and babiness) in 1,000 randomly generated vocabularies of a given size, and black dots indicate the observed proportion or mean for each child.

Figure 6

Many aspects of the form map to aspects of meaning in the pantomimic sign BRUSH. It also has an invisible referent (the brush itself is not represented in the form).