Donald O. Hebb > Quotes

“Why do we not accept ESP as a psychological fact? Rhine has offered enough evidence to have convinced us on almost any other issue... Personally, I do not accept ESP for a moment, because it does not make sense. My external criteria, both of physics and of physiology, say that ESP is not a fact despite the behavioral evidence that has been reported. I cannot see what other basis my colleagues have for rejecting it... Rhine may still turn out to be right, improbable as I think that is, and my own rejection of his view is - in the literal sense - prejudice.”
― Donald Hebb

“What about the computer? Does it think, and if so does that make it conscious? For the present at least, the answer is that it does not think in the sense that human beings and other mammals think and so is not conscious in the same sense. Furthermore, the mammalian brain is enormously more complex than any present computer, not only in the number of functional elements but also in its connections, the individual neuron frequently having synaptic connection with upwards of a thousand others. What I propose is that we have here a parallel with the physicist’s concept of a critical mass. Consciousness, that is, depends on a critical degree of complexity of neural action. Probably also it requires the kind or pattern of complexity characteristic of the structure of mammalian cortex. The individual neuron then is not conscious, nor any small group of interacting neurons. Consciousness appeared in evolution when thought became possible, and there is no evidence of thought in lower animals, even those with quite extensive nervous systems. It probably exists in birds such as the crow, but it has not actually been demonstrated except in mammals. In them the cortex is well developed, but vestigial or absent in other animal forms. The argument then is that a computer built on the plan of the mammalian brain, and of a complexity at least equal to that of the brain of the laboratory rat, might be conscious—given the same capacity to learn and a suitable early experience. This is unlikely, but conceivable.”
― Donald O. Hebb, Essay on Mind

“Psychology and philosophy were divorced some time ago, but like other divorced couples they still have problems in common.”
― Donald O. Hebb, Essay on Mind

“Thus also, T. S. Kuhn (1962): “I am, for example, acutely aware of the difficulties created by saying that when Aristotle and Galileo looked at swinging stones, the one saw constrained fall, the second a pendulum” (p.220). But the difficulties are verbal. The sensations were in principle the same, the perceptions differed. As the ambiguous figure shows, the same sensations may give rise to different perceptions. Perception is a cortical process, a first stage of thought, and consequently interpretive; both Aristotle and Galileo saw the same thing—swinging stones—but in effect thought about it differently, which should surprise no one.”
― Donald O. Hebb, Essay on Mind

“And this brought me back to the problem of the localization of a percept. The fundamental idea of the theory as it was later published (Hebb, 1949) was that repeated exposure to a given sensory stimulation will organize an assembly, and the difficulty I have already referred to now became inescapable. A familiar object is recognizable at different distances, at different angles, and in different parts of the visual field—left, right, above or below the direction of vision. In each case, the retinal stimulation is different and so a different cortical excitation results. In each case, it seemed, a separate assembly would be required, amounting to a large number for each recognizable object and meaning that visual recognition would have to be separately learned for each direction, distance, and aspect of the object as seen. An improbable conclusion, to say the least. Regretfully, I saw that the idea would not work. It was too interesting to give up entirely, but I could not take it seriously. The”
― Donald O. Hebb, Essay on Mind