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- RE: reply to Heschl
We are very grateful for Adolf Heschl’s reply, although we remain convinced that the touch hypothesis is the best explanation of our results. To remind the reader: in our paper we report three findings. First, that when pointing gestures are produced, the best predictor of what they refer to is not the angle of the pointing finger, which we called the ‘arrow-line’, but rather a line connecting the eye and finger-tip – the line on which you find the object that it looks to the pointer as if she is aiming to touch. Second, that when pointing at objects at odd angles, people rotate their wrists as they would were they trying to touch that object. And finally, we showed that infants are more likely to interpret pointing gestures to refer to the object that it looks as though a pointing figure is trying to touch, than an object that is found along the ‘arrow’ of the pointing finger. We argued that our results are be explained by the hypothesis that pointing gestures emerge from touch-exploration in infancy. Heschl argues that a better way to explain these results is on the basis of reaching – as Vygotsy and others have supposed may be the origin of pointing gestures.
First let us consider Heschl’s proposal for testing the reaching hypothesis in the context of our results.
Heschl proposes that an ‘arm line’ – a vector drawn along the arm from shoulder to wrist in a pointing gesture – will provide a good indicator of what a person is reaching for. If pointing orig...
Show MoreCompeting Interests: None declared. - RE: Why reaching is the origin of pointing
O’Madagain, Kachel, and Strickland (1) offer an impressive amount of data on pointing in human infants and adults, however, they propose a very unlikely origin of this unique behavior. The type of behavior from which they suggest pointing derives – touching of objects with the tip of the index finger – is a rather special movement pattern that represents only a small fraction of the whole arsenal of manual object explorations performed by the growing child. Accordingly, the literature on this kind of object manipulation is scarce. In fact, the only study cited by the authors that contains a relevant sample size (N = 109) (2) and not only casual descriptions of the behavior of two infants (Grey, Madeline) (3) does not support their hypothesis: Rochat (1989) defines so-called “fingering” as “the infant […] touching and scanning the object's surface with the fingertips of either one of the hands while the other is holding (grasping) the object”. This complex bi-manual object exploration is arguably quite different from mere touching of an object with the tip of the forefinger, as the authors think forms the behavioral basis of later pointing. In addition, the rarity of this behavior stands in striking contrast to the frequent occurrence of pointing in human children and presents another obstacle in the proposed developmental mechanism, i.e. ontogenetic ritualization. As Tomasello has shown, ritualization usually requires a comparatively high frequency of a given behavior...
Show MoreCompeting Interests: None declared.