The energetics of thought

Theodore L. SOURKES
Department of Psychiatry, McGill University, Montreal, Quebec, Canada


The discovery of the Law of Conservation of Energy in the 1840s had consequences for psychological theory. Does the process of thinking involve a novel form of energy that is not recognized by physical science? E. L. Youmans (1821-1887), commenting (1865) on “the correlation and conservation of forces,” stated, “mental operations are dependent upon material changes in the nervous system.” Kurd Lasswitz (1848-1910) introduced the term “psychophysical energy,” based upon the electrical activity of the brain. At the beginning of the 20th century Alfred Lehmann, Professor of Psychology at Copenhagen, sponsored experiments in his laboratory that attempted to measure psychical energy as a net increase in metabolism during mental work. He claimed that intense mental effort led to a net increase in oxygen utilization, and that this verified the existence of a specific psychic energy.

Hans Berger (1873-1941) adopted Lehmann’s views. In his lectures on psychophysiology (1921), he stated that “When psychical energy arises, an equivalent amount of another type of energy decreases. Psychical energy is derived by transformation of physical energy, and can again be converted back into it.” Chemical and electrical activity of the brain were the specific sources of that energy.

The energy balance experiments of the Benedicts in 1933, performed with the Atwater respiration calorimeter, showed that the increase of only a few percent in heat production during intense mental effort is probable due to attendant slight changes in muscular and cardiac activity.

Modern approaches to the problem include the Kety-Schmidt procedure for measuring cerebral oxygen utilization and PET scanning techniques. Their pertinence to “psychic energy” will be assessed.


Session III -- Muscle and Energy
Sunday, 27 June 2004, 11:25 am

Ninth Annual Meeting of the International Society for the History of the Neurosciences (ISHN)

Montreal, Quebec, Canada