What if you ask, for instance, ten Dutchmen and ten Ghanaians how big a clove of garlic is? Probably, many of them will answer something like: “…about this big...”, accompanied with a hand gesture to show what size they actually mean. This is not surprising, as gestures are much more efficient than speech when it comes to expressing size and shape. What might be surprising however, is the fact that speakers of different languages may differ radically in the type of gestures they use.
The first kind of difference in gestures can be identified when people of different languages and cultures use measure gestures, that is, gestures used to show size or shape. In the work we have done so far in the context of our project, we found that speakers of Dutch use the fingers and the thumb to delimit a short distance in space when gesturing size or shape, as shown in the picture on the right.
Speakers of Anyi (a language spoken in Ghana and Côte d'Ivoire) prefer to delimit the size on their arm or finger rather than showing it in space, as Dutch speakers generally do. The picture below shows a typical example of a measure gesture based on the arm of the speaker.
This may be described as a classical case of a cross-cultural difference. However, this distinction between gestures in space and gestures based on body parts is one of two ways in which gestures may differ across languages and cultures.
The other kind of variability is found in gestures people use to depict objects, particularly tools. For instance, when shown a picture of a toothbrush and asked to describe in gesture what they see on the picture, adults tend to mimic the manipulation of a toothbrush. In other words, they gesture the way they would use the toothbrush to depict the object with gesture. Young children and elderly people, on the other hand, tend to opt for a so-called ‘embodied strategy’: rather than manipulating a virtual object, they use a handshape that resembles the shape of the object. This kind of gesture, where the hand ‘becomes’ the object, is referred to as Body Part for Object.
The fact that these kinds of differences are associated with age has one interesting application in the diagnosis of brain damage. Adults with brain damage often pattern like young children and elderly people as well, so instead of using a gesture to show how they would use the object, they use their hand to ‘embody’ the object. Therefore, the use of such Body Part for Object errors are used as a diagnostic tool for assessing brain damage.
What follows from this is that the use of space or the body in measure gestures appears to follow from cultural conventions, while the use of space or the body in gestures representing objects appears to follow from brain condition. Classical question of nature and nurture, right? Unfortunately it is still difficult to say, because the language profile of participants in gesture studies is often not mentioned. This means that certain questions still remained to be answered. What if there are language-specific or culture-specific conventions for depicting objects as well? Could it be that the use of space or the body for size and shape gestures is not entirely nurture, but also a bit nature, for example, in the sense of being age-biased? Strikingly, in various countries (France, Macedonia, and Chechnya) body-part measure gestures are used, but reportedly mainly by older people.
Classical case of 'more research needed'.