communication

Chimpanzees use their own version of Broca's area when they communicate, according to a new PET scan study by Jared Taglialatela and colleagues. The abstract:

Broca's area, a cerebral cortical area located in the inferior frontal gyrus (IFG) of the human brain, has been identified as one of several critical regions associated with the motor planning and execution of language. Anatomically, Broca's area is most often larger in the left hemisphere, and functional imaging studies in humans indicate significant left-lateralized patterns of activation during language-related tasks [1], [2] and [3]. If, and to what extent, nonhuman primates, particularly chimpanzees, possess a homologous region that is involved in the production of their own communicative signals remains unknown. Here, we show that portions of the IFG as well as other cortical and subcortical regions in chimpanzees are active during the production of communicative signals. These findings are the first to provide direct evidence of the neuroanatomical structures associated with the production of communicative behaviors in chimpanzees. Significant activation in the left IFG in conjunction with other cortical and subcortical brain areas during the production of communicative signals in chimpanzees suggests that the neurological substrates underlying language production in the human brain may have been present in the common ancestor of humans and chimpanzees.

I wrote a couple of years ago about the Broca's area homolog in macaques, and the involvement of the area in planning time-sensitive action sequences in people. Those studies clearly foreshadowed the current result, since they provide both a phylogenetic expectation that this brain area evolved early in anthropoid evolution (or earlier), and the functional expectation that motor sequences characteristic of communication depend on it.

There is some uncertainty in the current analysis, because the PET scanning method doesn't localize the increased activity as tightly as they would like:

Although these data indicate that the left IFG is involved in the production of communicative signals in chimpanzees, cytoarchitectonically, it is not clear what cell types fully comprise this region [36]. Therefore, it is not possible to determine whether or not the neuronal metabolic activity reported in this study corresponds to an area within the chimpanzee IFG that contains Brodmann's area 44/45 cells -- those cells that comprise Broca's area in humans. In fact, additional areas of significant activation are observed in the frontal orbital gyrus and the frontal pole (Figure 2). Additional work is needed to explore the significance of these areas of activation.

Nice piece of work. I wouldn't want to be the one to get a chimp into a scanner...

References:

Taglialatela JP, Russell JL, Schaeffer JA, Hopkins WD. 2008. Communicative signaling activates 'Broca's' homolog in chimpanzees. Curr Biol 18:1-6. doi:10.1016/j.cub.2008.01.049

Paleontologist Neil Shubin has a guest post on Pharyngula, describing his experience preparing for an appearance on The Colbert Report. Shubin is the discoverer of Tiktaalik and author of the current book, Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body.

Being a scientist on the show carries with it some challenges. We need to convey facts of science correctly and do so in a way reveals how fun our science is to do and to think about. We need to educate, enlighten, and excite. The challenge is we need to do this in 5 minutes with Stephen Colbert sitting across the table. To make matters worse, the show does not tell you the tack Colbert is going to take in advance, largely because so much of what he does is ad lib.

Colbert has become the one place on television where you are most likely to see prominent scientists (of course, mostly hawking their books). I think Shubin's post is very interesting, as a reflection on how you prepare for a 5-minute interview. What he doesn't mention is that every scientist's education should include preparation for 5 minute interviews -- because that's exactly what we have to do hundreds of times as we are looking for work.

So students, read and learn!

There's a nice little article on the topic from Reuters:

CHICAGO - The arch of an eyebrow or the curve of a lip tells chimps a lot about each other, a finding that may give scientists new understanding about the evolution of human communication, researchers reported Friday.

Human faces can be easy to read, but sometimes people must look in different places on the face to get an accurate picture.

"What we know from humans is that even a single movement added to an expression can change the entire meaning," said Lisa Parr, director of the Yerkes National Primate Research Center at Emory University in Atlanta. "It can significantly affect the outcome of interactions."

The article describes Parr's work classifying facial expressions with the help of a computer program, and getting chimpanzees to try to identify expressions from cartoon images. It alludes to the difficulty of scoring what is essentially a continuous range of variation in expressions -- one of the reasons why the "analog" system of facial expressions poses interpretive difficulties.

There's no link to the original research, though -- if anybody knows where it is appearing, please let me know!

Chris Chatham has an informative post up about a current paper by Michael Tomasello and Malinda Carpenter, titled "Shared Intentionality."

Here's the abstract of the paper:

We argue for the importance of processes of shared intentionality in children's early cognitive development. We look briefly at four important social-cognitive skills and how they are transformed by shared intentionality. In each case, we look first at a kind of individualistic version of the skill - as exemplified most clearly in the behavior of chimpanzees - and then at a version based on shared intentionality - as exemplified most clearly in the behavior of human 1- and 2-year-olds. We thus see the following transformations: gaze following into joint attention, social manipulation into cooperative communication, group activity into collaboration, and social learning into instructed learning. We conclude by highlighting the role that shared intentionality may play in integrating more biologically based and more culturally based theories of human development.

The main idea is that the ability to direct shared attention and action with another individual (often the parent or caregiver) on third objects (toys, food, etc.) is a basic ability that emerges early in human ontogeny (one- and two-year-olds) and underlies human cognitive development. This explanation attempts to transform what seems magical (humans understand what each other are saying and thinking) into a simple shift in viewpoint (human children assume that other people are thinking about something, and the rest is learning.

The "aboutness" is the "intentionality" part. An intentional mental state is one that is about something.

In all four of these domains, apes are mostly concerned with their own individual goals. They use or exploit others - by gathering information from them, manipulating them as social tools, coordinating actions with them for their own benefit - and often compete with them as well. Human children, on the other hand, often are concerned with sharing psychological states with others by providing them with helpful information, forming shared intentions and attention with them, and learning from demonstrations produced for their benefit. The emergence of these skills and motives for shared intentionality during human evolution did not create totally new cognitive skills. Rather, what it did was to take existing skills of, for example, gaze following, manipulative communication, group action, and social learning, and transform them into their collectively based counterparts of joint attention, cooperative communication, collaborative action, and instructed learning - cornerstones of cultural living. Shared intentionality is a small psychological difference that made a huge difference in human evolution in the way that humans conduct their lives (Tomasello and Carpenter 2007:124).

Chris Chatham's post has a good ending -- which raises the problem of testing this theory of human intelligence in comparison with other potential alternatives:

Although humans and non-human primates differ in a variety of seemingly more important ways (e.g., language and enhanced working memory being just two), Tomasello suggests that "shared intentionality" is the most critical: a propensity for social interaction allowed each of these other capacities to evolve to their current state. In contrast, other theorists have hypothesized other "core differences," for example the use of recursive symbols. Unfortunately, it's difficult to imagine how some of these theories could be falsified, since we have little ability to infer "recursion" or "social intention" from the archeological record of early humans, and even if such data did exist, these differences could be incidental as opposed to causal factors in the development of human intelligence.

Edmund Blair Bolles' blog "Babel's Dawn" has a new post about joint attention as a prerequisite for language, which notes an argument by Lisbeth Nielsen (2002) that shared intentionality may first emerge from shared emotional experience:

An argument is developed that supports a simulationist account about the foundations of infants' and young children's understanding that other people have mental states. This argument relies on evidence that infants come to the world with capacities to send and receive affective cues and to appreciate the emotional states of others – capacities well suited to a social environment initially made up of frequent and extended emotional interactions with their caregivers. The central premise of the argument is that the foundation of infants' understanding of other minds is built upon an early-developing capacity to share others' emotion experiences. The emotion experiences elicited in interactions between caregivers and infants enable the elaboration of this primitive understanding into a more fully developed understanding of psychological subjects. The evidence presented in support of these claims derives from a wide range of studies of the phenomena of emotional contagion, affective communication, and emotion regulation involving infants, young children, and adults.

Emotion is a good candidate for early emergence of this ability -- it genuinely is early, it involves ancient facial, gestural, and vocal communication abilities, it is neurally related to pleasure and pain networks, and well-known to be linked to motivation and planning ability.

References:

Tomasello M, Carpenter M. 2007. Shared intentionality. Dev Sci 10:121-125. doi: 10.1111/j.1467-7687.2007.00573.x

Nielsen L. 2002. The simulation of emotion experience: on the emotional foundations of the theory of mind. Phenomenol Cog Sci 1:255-286. doi: 10.1023/A:1021359916894

If you've ever noticed that kids have the same facial expressions as their parents, you're not alone. The usual explanation for this similarity is learning -- kids watch their parents' facial expressions and then take them on themselves. This seems like a natural hypothesis considering another well-worn observation: that couples tend to resemble each other more and more over time. What more rational basis for this resemblance than subconsciously adopting each others' facial expressions?

But so far, we're really in "old wives' tale" territory. There is another hypothesis for similarity between parents and kids -- that their genes make them look similar. Peleg and colleagues (2006) have examined facial expressions in families to test whether genes underlie the variation to an observable extent.

The really interesting part is that they test a sample of blind subjects for similarities in facial expressions with their relatives.

Here's the abstract:

Although facial expressions of emotion are universal, individual differences create a facial expression "signature" for each person; but, is there a unique family facial expression signature? Only a few family studies on the heredity of facial expressions have been performed, none of which compared the gestalt of movements in various emotional states; they compared only a few movements in one or two emotional states. No studies, to our knowledge, have compared movements of congenitally blind subjects with their relatives to our knowledge. Using two types of analyses, we show a correlation between movements of congenitally blind subjects with those of their relatives in think-concentrate, sadness, anger, disgust, joy, and surprise and provide evidence for a unique family facial expression signature. In the analysis "in-out family test," a particular movement was compared each time across subjects. Results show that the frequency of occurrence of a movement of a congenitally blind subject in his family is significantly higher than that outside of his family in think-concentrate, sadness, and anger. In the analysis "the classification test," in which congenitally blind subjects were classified to their families according to the gestalt of movements, results show 80% correct classification over the entire interview and 75% in anger. Analysis of the movements' frequencies in anger revealed a correlation between the movements' frequencies of congenitally blind individuals and those of their relatives. This study anticipates discovering genes that influence facial expressions, understanding their evolutionary significance, and elucidating repair mechanisms for syndromes lacking facial expression, such as autism.

Turns out that Darwin had the idea first:

About 130 years ago, Darwin mentioned facial expressions in blind-from-birth individuals in the context of heritability: "The inheritance of most of our expressive actions explains the fact that those born blind display them, as I hear from the Rev. R. H. Blair, equally well with those gifted with eyesight" (Peleg et al. 2006:15922).

Still, the study is incomplete -- it has a small sample of subjects, and doesn't have the data to try to estimate the heritability of these expressions. Indeed, as "gestalts," the expressions themselves are statistically difficult to work with.

And speaking of facial expressions -- tonight's "Dancing with the Stars" show featured a body language expert examining how each of the competitors responds subconsciously to being judged. Mario Lopez takes a submissive posture when he is about to hear what the judges say, while Joey Lawrence licks his lips compulsively out of nervousness. They'd better stay out of poker games!

References:

Peleg G, Katzir G, Peleg O, Kamara M, Brodsky L, Hel-Or H, Keren D, Nevo E. 2006. Hereditary family signature of facial expression. Proc Nat Acad Sci USA 103:15921-15926. DOI link

Just taking some notes on a paper from last year by Helga Andresen, on the ways that role playing by preschool-age children can illuminate language and metacommunication development. I recognized a lot of my own children in the descriptions and examples.

Bateson (1955) postulates the existence of metalinguistic rules which determine how linguistic signs are related to non-linguistic entities like objects, persons, actions and places. These rules themselves, of course, cannot be linguistic in nature.

Bruner [1983] analyzed the development of mother-child interaction within the formats over many months and showed that the child constructs knowledge and anticipation of the interaction sequences and thus successively internalizes the structure of the format. This happens during the second half of the first year. First, the child adjusts his own vocalizations, miming and gestures to this structure until, more and more, he takes over the active part of the ongoing communication. Ritualization and repetition of the interaction make it possible for the child to recognize its structure. Above all, it is the close and fixed relations between verbal utterances and the non-verbal context that give children the chance to realize that the vocal activity of the mother refers to something beyond it and to realize the meanings of the utterances. Therefore the formats may be taken as an instantiation of those metalinguistic, non-verbal rules postulated by Bateson.

These considerations explain why early language use must be sympraxic; otherwise, children would have no chance to grasp the symbolic function of language (Andresen 2005:394).

Andresen has some fascinating examples where she documents interactions between children during roleplay, showing how much of the communication occurs within the roles and how much is metacommunication about the nature of the roleplay (a surprisingly large proportion).

The finding that older children produce less explicit metacommunication is of special interest. At first glance it may be surprising because from a scientific view it would be suggestive to propose that explicit metacommunication demands complex cognitive and communicative abilities which can be developed only on the basis of complex communicative skills which are beyond the scope of 4-year-old children. But metacommunication does not vanish out of play when children grow older; on the contrary, the pretend play of older children is much more complex than in the earlier years and contains a lot of transformations. Qualitative analyses of the older children's play in the Flensburg corpus show that they produce more implicit metacommunication than the younger ones. So, during the preschool period metacommunication changes from explicit to implicit performance (Andresen 2005:401-402).

A passage follows that discusses the complexity of carrying off implicit metacommunication -- which we may take as deliberately structuring communication in a form that itself more or less unambiguously conveys its context. In other words, implicit metacommunciation takes advantage of certain redundancies available in communication -- such as special same-meaning grammatical structures, gestures, tones, etc. -- to context-mark the communication.

Andresen then connects the progression from explicit to implicit in terms of Vygotsky's model of cognitive development:

According to [Vygotsky], internal mental processes arise out of external, interactive and communicative processes in earlier stages. He formulated this phenomenon as the transition from interpsychic to intrapsychic processes and functions during development (Andresen 2005:402).

And the subsequent section considers the development of egocentric speech along a similar timeline. Egocentric speech is inward-directed and regulatory in nature (with respect to actions); Andresen suggests a similar regulatory role for metacommunication. One might mention that egocentric speech has its own metacommunicative elements -- it being hard to mistake someone talking to herself for someone deliberately trying to communicate to others. In any event, this provides an opportunity to argue against simple word-object associations and in favor of the idea that roleplay indicates the ability to create linguistic (i.e., not here-and-now present) objects:

But an analysis of children's role plays clearly shows that already 4- year-olds are indeed able to create objects and meanings by linguistic means: for example, Aunt Maria, in the play of Hilde and Ingrid, who comes into existence through Hilde's utterance on the metacommunicative level and whose existence afterwards can be presupposed within the play. If the children could not create new meanings and communicate them to each other, role play could not take place at all (Andresen 2005:404).

There is a lot of detail in this article, related to the interchange of parent and child joint attention, the development of metacommunication skills in parent-child interactions, and the emergence of role playing as a way for children to take on adult roles they are normally not permitted. It relates well to Tomasello's work and Gregory Bateson's as well as Vygotsky, who is the model for much of the theory.

References:

Andresen H. 2005. Role play and language development in the preschool years. Culture and Psychology 11:387-414. DOI link