In NOT A CHIMP I devote a great deal of time discussing whether or not chimps, or any other animal species for that matter, can have any understanding of entities that are invisible - like mental states in the brains of other individuals and physical forces in the natural world - like gravity. I conclude that there is still no reliable evidence that chimps can mind read or have any grasp of "folk" or intuitive physics. Here, in an evol-psych group essay, editor Robert Karl Stonjek adds a third invisible to the array of cognitive powers we humans have and chimps don't - the absent referrant.
The Absent Referent
Robert Karl Stonjek
* * * * Black marks on the asphalt. A child's toy lays broken. * * * *
In their recent paper "Prelinguistic Infants, but Not Chimpanzees, Communicate About Absent Entities", Ulf Liszkowski, Marie Schäfer, Malinda Carpenter, and Michael Tomasello point out that chimps are unable to communicate information about the absent referent.
An experimenter places a favoured object away from baby/chimp subjects. Both are capable of gesturing their desire for the object. Then the object is placed behind a screen. Again, chimp and human subjects can gesture their interest in the object behind the screen.
Now the object is placed in a 'usual' location a few times, so that ape and human become familiar with the usual location of the object. And then the object is removed altogether (the location is now a referent for the absent object). The baby, but not the chimp, will gesture toward the absent referent and try to draw the attention of the experimenter to the missing object.
I speculate that infant chimps may also understand the absent referent but that adult chimps (as in this experiment) will not. I note that some dogs and cats will gesture toward their empty bowls when water or food is absent (my cat will do this when the bowl is running low and it wants the bowl placed outside the door for the night.)
But the absent referent is much more than this in humans. The absent referent acquires a property attributable to the referent that is absent. The imagery at the head of this essay conjures an image of a child hit by a motor car, even though there is no evidence of such an event. The lost wedding ring that is replaced by a new one is not the same because of the absent referent. 'Qualia' can be thought of as the referent which is absent (properties implied by the target object).
Humans not only see or have knowledge of the referent which is absent, they perceive its vestige as a property of the thing from which it is absent. We say that grandpa's walking stick reminds us of him, but we also perceive something of grandpa in the walking stick which is why we want to keep it. If it were just a reminder then a replica would be sufficient.
Tools may be a simple as a particularly shaped stone. But the stone tool takes on a special character when the ability to perceive the absent referent has evolved. The use of the tool remains with that tool, we see it (the absent referent). If we gained status at the time of using the tool, then that status remains with the tool as an additional absent referent. The tool takes on those qualities ~ status and utility ~ even though the tool is not being used. Thus humans readily kept tools and defended the possession of them in the same way they defend any other aspect of their status.
Words can be characterised as having a denotation (the bland dictionary meaning) and a connotation (the feeling the word evokes, its inner meaning or personal meaning to us). The connotation is the absent referent ~ the thing that the word refers to, even when the thing is not present. The feeling behind every word, that which gives the word meaning, can be traced back to the absent referent that the baby described above 'sees' when pointing to the place where the favoured object usually sits ~ the chimp does not 'see' it.
Not all words map directly onto concrete objects or actions. There is a long and complex cognitive road between the simplest absent referent and the full language we currently use. But the same root form gives rise to art, music, language, the concept of future and past, religion and all else that makes up human culture. Absent referents can be manipulated as abstract or symbolic forms.
As mentioned earlier, I think it is highly probable that the precursor of humans with language would have had absent referent capability as children and this would have been a necessary part of playing behaviour. When the ability to model the absent referent entered adulthood, probably due to a single gene mutation, we had the genesis of all that is uniquely human.
Are we humans simply remodelled apes? Chimps with a tweak? Is the difference between our genomes so minuscule it justifies the argument that our cognition and behaviour must also differ from chimps by barely a whisker? If “chimps are us” should we grant them human rights? Or is this one of the biggest fallacies in the study of evolution? NOT A CHIMP argues that these similarities have been grossly over-exaggerated - we should keep chimps at arm’s length. Are humans cognitively unique after all?
Thursday, 19 November 2009
Symbolic Gestures And Spoken Language Are Processed By A Common Neural System
Excellent paper by a team which includes Pat Gannon. I cannot do better than to reproduce the abstract and for those of you more interested, and not able to source PNAS normally through a university library system, this is one of their open access articles - its free!
Abstract
Symbolic gestures, such as pantomimes that signify actions (e.g., threading a needle) or emblems that facilitate social transactions (e.g., finger to lips indicating “be quiet”), play an important role in human communication. They are autonomous, can fully take the place of words, and function as complete utterances in their own right. The relationship between these gestures and spoken language remains unclear. We used functional MRI to investigate whether these two forms of communication are processed by the same system in the human brain. Responses to symbolic gestures, to their spoken glosses (expressing the gestures' meaning in English), and to visually and acoustically matched control stimuli were compared in a randomized block design. General Linear Models (GLM) contrasts identified shared and unique activations and functional connectivity analyses delineated regional interactions associated with each condition. Results support a model in which bilateral modality-specific areas in superior and inferior temporal cortices extract salient features from vocal-auditory and gestural-visual stimuli respectively. However, both classes of stimuli activate a common, left-lateralized network of inferior frontal and posterior temporal regions in which symbolic gestures and spoken words may be mapped onto common, corresponding conceptual representations. We suggest that these anterior and posterior perisylvian areas, identified since the mid-19th century as the core of the brain's language system, are not in fact committed to language processing, but may function as a modality-independent semiotic system that plays a broader role in human communication, linking meaning with symbols whether these are words, gestures, images, sounds, or objects.
Abstract
Symbolic gestures, such as pantomimes that signify actions (e.g., threading a needle) or emblems that facilitate social transactions (e.g., finger to lips indicating “be quiet”), play an important role in human communication. They are autonomous, can fully take the place of words, and function as complete utterances in their own right. The relationship between these gestures and spoken language remains unclear. We used functional MRI to investigate whether these two forms of communication are processed by the same system in the human brain. Responses to symbolic gestures, to their spoken glosses (expressing the gestures' meaning in English), and to visually and acoustically matched control stimuli were compared in a randomized block design. General Linear Models (GLM) contrasts identified shared and unique activations and functional connectivity analyses delineated regional interactions associated with each condition. Results support a model in which bilateral modality-specific areas in superior and inferior temporal cortices extract salient features from vocal-auditory and gestural-visual stimuli respectively. However, both classes of stimuli activate a common, left-lateralized network of inferior frontal and posterior temporal regions in which symbolic gestures and spoken words may be mapped onto common, corresponding conceptual representations. We suggest that these anterior and posterior perisylvian areas, identified since the mid-19th century as the core of the brain's language system, are not in fact committed to language processing, but may function as a modality-independent semiotic system that plays a broader role in human communication, linking meaning with symbols whether these are words, gestures, images, sounds, or objects.
Wednesday, 18 November 2009
Right-Handed Chimps Provide Clues To The Origin Of Human Language
More good news for those scientists who support the idea that human language evolved from the use of intentional gestures. Bill Hopkins, and French colleagues, have been recording communicative gestures in chimps for years and have found a highly significant bias to use of the right hand in communicative gestures used in contexts like attention getting, shared excitation, threat, aggression, greeting, reconciliation, and overtures to play. This, of course, implies left lateralization of the brain for these gestures. As the scientists conclude: "This finding provides additional support to the idea that speech evolved initially from a gestural communication system in our ancestors. Moreover, gestural communication in apes shares some key features with human language, such as intentionality, referential properties and flexibility of learning and use."