Published online by Cambridge University Press: 01 January 2020
John Locke:
When we set before our eyes a round globe of uniform colour, v.g. gold, alabaster or jet, it is certain that the idea thereby imprinted in our mind is of a flat circle, variously shadowed, with several degrees of light and brightness coming to our eyes. But we having, by use, been accustomed to perceive what kind of appearance convex bodies are wont to make in us, what alterations are made in the reflections of light by the difference of the sensible figures of bodies: the judgment presently, by an habitual custom, alters the appearances into their causes.
H.H. Price:
…. a distant hillside which is full of protuberances, and slopes upwards at quite a gentle angle, will appear flat and vertical…. . This means that the sense-datum, the colour expanse which we sense, actually is flat and vertical.
1 Essay Concerning Human Understanding (London: Ward, Lock n.d.), Book II, Chapter IX, Section 8, 93-4
2 Perception (London: Methuen 1932) 30
3 Yolton, John (in Perceptual Acquaintance from Descartes to Reid [Minneapolis, MN: University of Minnesota Press 1984]Google Scholar) has argued that this is a misunderstanding of Locke. Yolton's thesis is extremely implausible. There is scarcely room for more than one interpretation of the words’ … it is certain that the idea thereby imprinted on the mind is of a flat circle, variously shadowed ….’ But I will not discuss Yolton's argument, because I am not engaged here in historical scholarship. It is the theory Locke appears to hold that I am interested in, whether or not he did hold it. I have singled out the passages from Locke and Price only because it is exceptional to find anyone raising the question of the dimensionality of ideas or sense-data, and we are thereby provided with a more than usually specific issue to examine in evaluating sense-data theories.
4 This and the preceding two experiments are described in Ittleson, W.H. The Ames Demonstrations in Perception (New York: Hafner Publishing 1968)Google Scholar.
5 See Johansson, Gunnar ‘Visual Motion Perception,’ in Scientific American 232 (1975) 80.CrossRefGoogle ScholarPubMed
6 Austin, J.L. Sense and Sensibilia (Oxford: Oxford University Press 1962) 30Google Scholar
7 David Marr, in Vision (San Francisco, CA: W.H. Freeman 1982) addresses himself to the problem how, from images, we discover ‘what is present in the world, and where it is’ (3), or how we ‘reliably derive properties of the world from images of it’ (23). He supposes that in performing these tasks, the brain functions like a computer, and his problem is to work out what sorts of computations it does. He does not, any more than did Locke or Price or countless others, make it a question for investigation whether we start with images.