Does the pressure to communicate effectively explain differences in iconic strategy between signers and gesturers?

In sign languages, it is common for words to be highly iconic, with the form of a word having some non-arbitrary resemblance to the real life thing it refers to (Sandler & Lillo-Martin, 2006). For example, in American Sign Language, the word for ‘bird’ features the opening and closing of the hand in front of the mouth, mimicking a bird’s beak. Iconic forms in sign language can often be categorised in terms of iconic strategies — distinct methods of conveying something iconically. For words involving handheld objects, prominent iconic strategies are handling, where the signer’s hand mimics the shape of a hand using the object, and instrument, where the signer’s hand mimics the shape of the object itself (Padden et al., 2013).

Across different sign languages, the usage of these different strategies varies drastically (Nyst et al., 2021). In general though, an unexplained pattern has been noticed, where sign languages will use the instrument strategy significantly more than silent gesturers (non-signers prompted to convey a meaning through gesture). In contrast to the mix of instrument and handling signs typical of sign languages, silent gesturers overwhelmingly prefer the handling strategy (Padden et al., 2015). To explain this, I hypothesise that the instrument strategy tends to be more communicatively effective, and as a result is selected for over time, becoming more frequent over sign languages’ evolution. Specifically, I hypothesise that because handshapes while holding different object are often very similar, the handling strategy would lead to higher rates of homophony, and tend to be less effective at communicating a specific intended meaning.

To test this hypothesis, I will run two experiments. The first involves showing a large number of participants videos of gestures using one of the two iconic strategies, and asking them what they think the intended meaning of the gesture was. In support of the hypothesis that the instrument strategy will be more effective at communicating a narrow meaning, I predict that videos of instrument gestures will receive a narrower range of proposed meanings. The second experiment will show participants two videos — one instrument and one handling gesture for the same object — and ask them which they prefer for the intended meaning. Participants will be in one of two conditions, one with and one without a communication pressure. Hypothesising that more effective strategies will be more common when a communication pressure is present, I predict that the instrument video will be favoured more often when there is a communication pressure.

If these hypotheses are supported, it will add choice of iconic strategy in sign language to a growing list of linguistic features that may be explained by the pressures involved in language acquisition and communication (c.f. Slobin, 1977; Smith, Tamariz & Kirby, 2012).

References: 

Nyst, V., Morgado, M., Mac Hadjah, T., Nyarko, ... & Schüller, A. (2021). Object and handling handshapes in 11 sign languages: towards a typology of the iconic use of the hands. Linguistic Typology.

Padden, C., Hwang, S. O., Lepic, R., & Seegers, S. (2015). Tools for language: Patterned iconicity in sign language nouns and verbs. Topics in Cognitive Science, 7(1), 81-94.

Padden, C. A., Meir, I., Hwang, S. O., Lepic, R., Seegers, S., & Sampson, T. (2013). Patterned iconicity in sign language lexicons. Gesture, 13(3), 287-308.

Sandler, W., & Lillo-Martin, D. (2006). Sign language and linguistic universals. Cambridge University Press.

Slobin, D. I. (1977). Language change in childhood and in history. Language learning and thought, 185-214.

Smith, K., Tamariz, M., & Kirby, S. (2013). Linguistic structure is an evolutionary trade-off between simplicity and expressivity. In Proceedings of the annual meeting of the cognitive science society (Vol. 35, No. 35).