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'

Abstract

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.

WEIRD People and BIZARRE Chimps

The article "the weirdest people in the world?" (which I already mentioned last year, here), has finally been published in the current issue of the Behavioral and Brain Sciences (subscription needed, preprint can be found here).

In this article, Joseph Henrich, Steven J. Heine and Ara Norenzayan from the University of British Columbia in Vancouver, Canada, argue that

"Behavioral scientists routinely publish broad claims about human psychology and behavior in the world’s top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies."

Henrich et al. question whether these 'standard' subjects are really representative of homo sapiens as a species and instead hold that there is a substantial variability across cultures in domains such as

"visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ."

The data they review indicate that both adults and children living in WEIRD societies

"are among the least representative populations one could find for generalizing about humans."

This position is sure to cause much debate, especially given that the article contains such tongue-in-cheek parts as mentioning that psychologists would surely bristle if the premier journal in social psychology, the "Journal of Personality and Social Psychology", would be renamed to more accurately reflect its main sample: "Journal of Personality and Social Psychology of American Undergraduate Psychology Students" (Henrich et al. 2010: 63)

This is why the target article is accompanied by 28 commentaries, which interestingly, are too a large extent quite positive. What is less surprising is that many of the commentaries use the acronym WEIRD for puns or come up with their own ones.

Here's a sample of the titles:

• Weird people, yes, but also weird experiments (Baumard & Sperber 2010)
• Weirdness is in the eye of the beholder (Bennis & Medin 2010)
• It’s not WEIRD, it’s WRONG: When Researchers Overlook uNderlying Genotypes, they will not detect universal processes (Gaertner et al. 2010)
• Wired but not WEIRD: The promise of the Internet in reaching more diverse samples (Gosling et al. 2010)
• ODD (observation- and description-deprived) psychological research (Rai & Fiske 2010)
  
• In a very interesting article, Leavens et al. (2010) claim that "BIZARRE chimpanzees do not represent “the chimpanzee.”" They caution that great apes from "Barren, Institutional, Zoo, And other Rare Rearing Environments" (BIZARRE) differ cognitively from great apes living in the wild. This makes it dangerous to make generalized statements about the cognitive capacities of great apes that are based mainly on experiments with BIZARRE apes. This is also the main thrust of the commentary by primatologist Christophe Boesch.

Leavens et al. (2010: 101) also have a very interesting graph comparing the pointing behaviors of wild chimpanzees, instituationalized chimpanzees and home-raised or language trained-chimpanzees, which varies markedly from one another. Rearing history and early development thus seem to be able to influence the pointing behaviour and interaction skills of chimpanzees quite heavily.

This is especially important given that researchers like Michael Tomasello and others argue that pointing declaratively to help, inform, and share motives and attitudes in a rich interactive setting characterized by joint attention, shared intentionality, common ground, as well as role- and perspective-taking is the key human cognitive specialization that makes us human and separates us from the other apes.

Most strikingly, in Leavens et al. 's (2010) analysis, chimpanzees also point declaratively, but this is contested by other researchers (e.g. Tomasello 2006, Tomasello 2008, see here). The main question here is how to understand "declarative pointing" and the cognitive capacities behind it, but this is a difficult topic. For Tomasello "declarative pointing" involves "a declarative motive" which

"assumes a partner with the psychological states of interest and attention, which one can then attempt to share."

And according to Tomasello, chimpanzees lack this understanding (Tomasello 2006).
Leavens et al. on the other hand define "declarative pointing" as

"Pointing to draw somebody’s attention to an object or event; includes responses to queries, such as pointing to an object when asked where that object is."

Tomasello would argue that the latter part does not belong into the category of declarative pointing as these kinds of gestures are not to be seen as as truly declarative or informative, as they are more

„recognitory or classificatory, as the ape simply recognizes something and produces the associated sign in recognition“ (Tomasello 2008: 38)."

But as Leavens et al. (2010) also claim that chimpanzees point "to draw somebody’s attention to an object or event" and not only as a direct classificatory reaction, this stands in direct contrast to Tomasello's position. I'm very interested in how this debate will continue.

Michael Tomasello - The Origins of Human Communication (summary pt. 3)

I wanted to finish this summary on the weekend but just didn't get round to it because I've got a lot to do right now. Here it is anyway:

Like I said in my last post, the rest of Chapter 2 focuses on what in the chimpanzee/human lineage provided a basis for modern language.

Pointing

One crucial factor is chimpanzees' ability to use and comprehend pointing.

In the wild, chimpanzee pointing is very rare. But approximately 60 to 70 percent of all captive chimps spontaneously use pointing in an imperative manner in their interactions with humans, e.g. by pointing to food that is out of reach as a request for the human to get it. But pointing gestures that aren't imperative are virtually absent. This even applies to language-trained apes such as Kanzi. In the few studies that have been done on this, 96-98 percent of all their pointing were imperative. The other 2-4 had no clear function.

Thus there is nothing in chimpanzees' pointing behavior that would suggest that they are capable of or interested in sharing attention within a joint attentional frame.

On the other hand, in a Brain Science Podcast interview, Stuart Shankar, co-author of The First Idea: How Symbols, Language, and Intelligence Evolved From Our Primate Ancestors to Modern Humans , reports of a an encounter he had with the bonobo Panbanisha in which she showed him various plants and classified them, for example, as poisonous. Shankar interprets this as truly sharing attention and informing for the the sake of informing, but Tomasello argues that these kinds of gestures are not to be seen as as truly declarative or informative, as they are more

„recognitory or classificatory, as the ape simply recognizes something and produces the associated sign in recognition“ (Tomasello 2008: 38).

Comprehending Pointing

Interestingly, chimpanzees are much worse comprehending other people's pointing than they are producing it themselves.

In a cool experiment, Tomasello and his colleagues have shown that in a cooperative situation, chimpanzees are unable to grasp the fact that the hidden food is in the bucket that the experimenter is pointing to. Human infants, on the other hand, are able to understand this task by 14 months of age. (Behne et al. 2005) In a competitive version of this task, however, chimpanzees fare much better (Hare & Tomasello 2005). These results suggest that chimpanzees have problems with "shared intentionality," i.e. recognizing situations where you have shared cooperative goals with others and have the same shared attentional frame.

Intentionality & Perception

According to Tomasello, apes and young human children both attribute simple forms of intentionality to other actors. For example, when a human repeatedly tries to give food to a chimpanzee but fails because he is clumsy, the chimp reacts patiently, whereas he gets frustrated when the human is failing to pass him the food for no good reason or because of unwillingness.

Most of the time enculturated chimpanzees also imitate

“demonstrator’s action more often when he freely chose his action than when he was forced to use it by some constraint” (Buttelman et al. 2007: F37, see here).

Crucially, chimpanzees also understand that others have perceptions and see things. In a competitive task with a dominant chimpanzee, for example, subordinate chimps, secretly take a food reward when the other one is unable to see him, but not when the food can be seen by the dominant chimp.

According to Tomasello then,

"The overall conclusion is thus that apes understand others in terms of their goals and perceptions and how these work to determine behavioral decisions, that is, they understand others as intentional, perhaps even rational, agents (Tomasello 2008: 4)

Intentionality + gestural fexibility = evolutionary foundations of language ?

This seems to be the conclusion Tomasello draws at the end of the second chapter. Clearly, when a chimpanzee produces a gesture, he does this in a very flexible manner that even shows sensitivity to the attention of the other. Ape vocalizations on the other hand are mostly inflexible and do not take into account the presence or absence of attention to the displays. Thus there is strong evidence that the capacities apes display in the gestural modality

"are the original font from wich the richness and complexities of human communication and language have flowed. " (Tomasello 2008: 55).

References:

Behne, T., Carpenter, M., and Tomasello, M. (2005). One-year-olds comprehend the communicative intentions behind gestures in a hiding game. Developmental Science, 8, 492–499.

Buttelmann, D., Carpenter, M., Call, J., and Tomasello, M. (2007). Enculturated apes imitate rationally. Developmental Science, 10, F31– 38.

Hare, B., and Tomasello, M. (2004). Chimpanzees are more skillful in competitive than in co-operative cognitive tasks. Animal Behaviour, 68, 571–581.

Tomasello, Michael (2008): The Origins of Human Communication. Cambridge, MA; London, England: MIT Press.

Michael Tomasello - The Origins of Human Communication (summary pt. 1)

A pretty long time ago – before I went to Nottingham for my year abroad – I announced that I would write some more about Michael Tomasello's new (2008) book The Origins of Human Communication.

Although I haven't finished the book yet, and I don't know if I can really contribute something not already covered in Edmund Blair Bolles' interesting multi-part book review over at Babel's Dawn (see here, here, here, and here), I thought I'd still give it a go and see how it turns out.

I hope the next few posts will at some point intersect with a post about Tomasello's arguments against linguistic innateness and his view of language acquisition (e.g. Tomasello 2003), which I have been meaning to write for ages.

Tomasello's main interest in this book is to flesh out “the social-cognitive and social-motivational infrastructure” (2) that enables modern human communication. He also tries to present a plausible evolutionary scenario of how we arrived at this point.

His hypothesis is that “the first uniquely human forms of communication were pointing and pantomiming.” (2)

Social Cognition




In a close analysis of pointing and pantomiming in infancy Tomasello arrives at the conclusion that they already embody

“most of the uniquely human forms of social cognition and motivation required” (2) for full-blown linguistic communication. They are thus perfect candidates for “the critical transition points in the evolution of human communication” (2)

The reason why Tomasello sees pointing as the primordial form of human communication is the following:

Imagine we are walking to the library and I point out some bicycles leaned against the wall to you. Without “context” this would be entirely meaningless. However, if we share some kind of “common ground”, some kind of previous knowledge or past experience the otherwise empty gesture suddenly can be 'filled' with a variety of meanings. “By itself, pointing means nothing," but if we both have knowledge of the fact that one of the bikes is your ex-boyfriend's, with whom you just had a nasty break-up, or if one of the bikes was the one stolen to you some days ago, you are suddenly able to interpret my gesture in a meaningful way. You are thus able to answer to the question.

“what is his intention in directing my attention in this way?” (4)

This example leads Tomasello to the conclusion that

“The ability to create common conceptual ground— joint attention, shared experience, common cultural knowledge—is an absolutely critical dimension of all human communication.” (5).

This enables a richness of meaning and reference all other forms of primate communication lack.

Social Motivation

As Tomasello remarks the second important and unique aspect is the prosocial motivation of the pointing example. In this example and in dozens of other examples from early infancy on, there is no ulterior motive to somebody pointing other than to simply being helpful and cooperative. Apes on the other hand, usually don't point in natural contexts, and they never point cooperatively just to inform somebody of something.

In contrast, there is evidence of infants as young as 12 months pointing for others just to share attention or inform them of something.
Here's one of the examples Tomasello (2008: 114f.) mentions, which is taken from a study by Carptenter et al. (in prep.)

"At age 13.5 months, while Mom is looking for a missing refrigerator magnet, L points to a basket of fruit where it is (hidden under the fruit). Gloss: Attend to the basket of fruit; it’s there."

Another example particularly fitting for this season is reported by Tomasello (2008: 114):

“At age 13 months, J watches as Dad arranges the Christmas tree; when Grandpa enters the room J points to tree for him and vocalizes. Gloss: Attend to the Christmas tree; isn’t it great?”

These cooperative capacities form the ability often called “shared intentionality.”

In general,

"shared intentionality is what is necessary for engaging in uniquely human forms of collaborative activity in which a plural subject “we” is involved: joint goals, joint intentions, mutual knowledge, shared beliefs—all in the context of various cooperative motives” (6f.)

The key aspect of human communication is thus that it is

“a fundamentally cooperative enterprise, operating most naturally and smoothly within the context of (1) mutually assumed common conceptual ground, and (2) mutually assumed cooperative communicative motives.” (6)

Following these assumptions, Tomasello then sets out to identify “the species-unique features of human communication and their ontogenetic and phylogenetic roots.” (11)

I'll write more about this in my next post.

References:

Tomasello, Michael (2003): Constructing A Language. A Usage-Based Approach. Cambridge, Massachusetts; London, England: Harvard University Press.

Tomasello, Michael (2008): The Origins of Human Communication. Cambridge, MA; London, England: MIT Press.