In "The Roots of Thinking," Sheets-Johnstone (1990) suggests that human conceptual thinking originates in universals of sensory experience. She contrasts the tactile-kinaesthetic sense with "static" visual cognition, favoring the former. In contrast, archaeologists have often interpreted the data on early conceptual thinking as reflecting the dominance of the visual modality. This is illustrated in the origins of figurative art. Deciding between these competing accounts of sensory "dominance" may require more input from disciplines in which behaviour is directly manipulated and observed.
2. As an archaeologist, I found ROOTS highly stimulating, particularly the last section, in which Sheets-Johnstone defends the possibility of "empathetic" projection into the subjective experience of earlier hominids on the basis of a shared somatic morphology. Colleagues in cognitive psychology will no doubt comment on this; one area to explore in developing this argument would be the cross-species comparisons of primate somatosensory "homunculi" in the cerebral cortex. If differences in the proportional cortical representation of different body surfaces reflect not just their level of innervation and neocortical afferentation but also their subjective salience, then understanding the rules of cortical representation for body surfaces will enable us to reconstruct an important aspect of comparative subjectivity across species. For example, is the hand proportionally better represented in the human than the nonhuman primate somatosensory cortex as a consequence of the "freeing of the hands" by consistent bipedalism? Possible connections between tactile ability and sensory representation of the hand in nonhuman primates have been discussed by Carlson (1985).
3. Central to ROOTS is the argument that vision has been culturally privileged over tactile-kinaesthetic awareness in Western science, and that touch and feel are more fundamental than sight as sources for abstraction in conceptual thinking. No doubt there are experimental studies in the psychological literature which examine the conditions of dominance of one or another modality under conditions where they compete for attention in the brain's executive system. I would point out that this issue can also be argued through in debating current interpretations of the archaeological record of early artefacts.
4. Let us consider the example of Upper Palaeolithic cave art (ROOTS, chapter 9). Sheets-Johnstone argues that the location of cave art is significant because of the analogy between the transformative processes associated with enclosed body spaces and the sensory experience of enclosed cave spaces. The origin of figurative drawing is grounded by Sheets-Johnstone in the act of drawing itself, with what was originally accidental manual tracing of lines on surfaces leading to the discovery of topology and enclosure as the basis of shape representation. The symbolic force of art thus originates in manual tracing of lines on surfaces and in the analogy between the effects of traced shapes and the transformative power of physiological enclosure.
5. Sheets-Johnstone's emphasis on the tactile aspects of art production should be contrasted with an account of its origins which focuses on the visual modality, developed from ethnographic analogy by Lewis-Williams and colleagues. Lewis-Williams and Dowson (1988) have interpreted the cave art using ethnographic information on the shamanistic rock art of the San and of the Shoshonean Coso, coupled with neuropsychological work on "entoptic phenomena": Generated in drug- or activity-induced "trance states," these culturally universal geometric forms are based on the internal structure of the visual system. The hallucinated images include "phosphenes," often deriving from direct physical stimulation of the eyeball, and "form constants," deriving from higher processing levels of the visual system. Lewis-Williams and Dowson argue that the earliest artistic depictions in the archaeological record are geometric rather than iconic markings, and that representational imagery appears later as a progression from the initial "fixing" of these fragmented entoptic hallucinations. The remote and isolated locations of most of this ancient rock art are explained as providing conditions "especially conducive to the generation of entoptic phenomena and hallucinations" (1988, p. 214). The superposition of images in these locations is then explicable partly as the product of repeated visits to such locales. According to this view, the conceptual origins of cave art are grounded very firmly in the visual system rather than being tactile-kinaesthetic.
6. It is not clear to me that the question of the dominance of one or another sense modality in human conceptual origins can be answered primarily through appeals to the archaeological record. Sheets-Johnstone points out quite reasonably that archaeologists are bound to refer to analogies with directly observable behaviour in accounting for the appearance of new forms of artefact in the Palaeolithic record. These analogies derive from ethnography and primatology; they suggest the existence of certain human behavioural universals and they are validated by arguments for the uniformity of the causal structure of past and present worlds. For this reason, the debate about the dominance of the visual versus the tactile-kinaesthetic modality in hominid cognition must be pursued in other disciplines, where behaviour can be directly manipulated and observed, as well as in discussions of the interpretation of archaeological data. The resolution of this debate will be of the greatest interest to archaeologists working on the Palaeolithic data.
Carlson, M. (1985) Significance of single or multiple cortical areas for tactile discrimination in primates. In A.W. Goodwin and I. Darian-Smith (eds.) Hand Function and the Neocortex, pp. 1-16. Berlin: Springer-Verlag.
Kaye, L.J. (1993) Are most of our concepts innate? Synthese 95:187-217.
Lewis-Williams, J.D. and Dowson, T.A. (1988) The signs of all times. Current Anthropology 29: 201-217.
Sheets-Johnstone, M. (1990) The Roots of Thinking. Philadelphia: Temple University Press.
Sheets-Johnstone, M. (1994) Precis of The Roots of Thinking. PSYCOLOQUY 5(8) evolution-thinking.1.sheets-johnstone.