Sunday, March 27, 2011

The relation between pointing and language development

The December 2010 issue of 'Developmental Review' features a nice meta-analysis of of studies on pointing and language development by Cristina Colonnesia, Geert Jan J.M. Stamsa, Irene Kostera, and Marc J. Noomb. Here's their abstract and their 'research highlights'

The use of the pointing gesture is one of the first ways to communicate with the world. This gesture emerges before the second year of life and it is assumed to be the first form of intentional communication. This meta-analysis examined the concurrent and longitudinal relation between pointing and the emergence of language. Twenty-five studies were included into the meta-analysis, including 734 children. The role of several moderators was examined: pointing modality, pointing motive, age at which the pointing was measured, the assessment method of the pointing gesture and language development, the modality of language, SES, and country. The results showed both a concurrent (r = .52) and a longitudinal (r = .35) relation between pointing and language development.
The relation between pointing and language development became stronger with age, and was found for pointing with a declarative and general motive, but not for pointing with an imperative motive. It is concluded that the pointing gesture is a key joint-attention behavior involved in the acquisition of language.

Research highlights
► Pointing gesture is concurrently (r = .52) and longitudinally (r = .35) related to language development. ► The relation between pointing gesture and language becomes stronger with age, in particular during the end of the second year of life. ► Both the production (r = .33) and the comprehension (r = .38) of pointing gesture are related to language development. ► Pointing with a declarative (r = .39) and with a general motive (r = .39), rather than with an imperative motive (r = .04), are related to language.

Monday, March 21, 2011

The need for multimodality in primate communication research

Barbara King points to a very interesting article in press at Animal Behaviour. In their essay "The language void: the need for multimodality in primate communication research" Katie Slocombe, Bridget Waller and Katja Liebal analyse more than 550 studies on primate communication from 1960 to 2008 and argue that research in one modality (e.g. gesture) often differs so strongly in its methodology from research on another modality (e.g. alarm calls) that the results can hardly be reliably compared. Here's their abstract:

Theories of language evolution often draw heavily on comparative evidence of the communicative abilities of extant nonhuman primates (primates). Many theories have argued exclusively for a unimodal origin of language, usually gestural or vocal. Theories are often strengthened by research on primates that indicates the absence of certain linguistic precursors in the opposing communicative modality. However, a systematic review of the primate communication literature reveals that vocal, gestural and facial signals have attracted differing theoretical and methodological approaches, rendering cross-modal comparisons problematic. The validity of the theories based on such comparisons can therefore be questioned. We propose that these a priori biases, inherent in unimodal research, highlight the need for integrated multimodal research. By examining communicative signals in concert we can both avoid methodological discontinuities as well as better understand the phylogenetic precursors to human language as part of a multimodal system.

Barbara King's discussion of the article is also very illuminating.

Wednesday, March 2, 2011

John Hawks: How language eats brains, and why it matters to language evolution.

John Hawks has posted a fascinating discussion of a new paper published in the Proceedings of the National Academy of Sciences (here) by Bedny et al. that shows that in congenitally blind adults, "brain regions that are thought to have evolved for vision can take on language processing as a result of early experience." (to quote from the abstract) (see also John Lehrer's discussion, here)

These results show the brain's immense plasticity, especially in early development. Crucially, the fact that "brain regions that did not evolve for language can nevertheless participate in language processing" (Bedny et al.) poses the questions whether language-specific processing functions need to have evolved at all.

To quote from John Hawk's discussion at lenght:

"The blind subjects tell us that the ground for language processing is almost as fertile elsewhere in the cortex. Many brain areas have the genetic equipment to recruit and organize neurons into useful circuits for language processing. Language development is developmentally robust because it can rely on a rich language environment, not because of genetic standardization. The basic problems of language evolution must be explained by showing how robust language communities emerged. I don't preclude genetics, far from it -- weaker language environments may have become stronger because of evolutionary change. But that evolution must have been substantially domain-general, because language processing is not specifically canalized by genetics.

I like this scenario because it means we shouldn't be looking for lots of language-specific genetic changes in the last few hundred thousand years. The Neandertal genome suggests that there may not have been any at all"

To me, these results also seem compatible with arguments made by Morten Christiansen, Nick Chater, and others, who argue that language was shaped by the human brain and its learning and processing mechanisms, instead of there being a language-specific biological endowment. On this view, then "language evolution is a process of cultural change, in which linguistic structures are shaped through repeated cycles of learning and use by domain-general mechanisms" (Chater & Christiansen 2010).

UPDATE [21/03/11]: John Hawks has written another highly interesting post that is also relevant to this topic and the question of the evolution of language and cognition more generally: The development of sharing and cooperation from infancy to school-age and (here).