Of the Imagination as a Cause and as a Cure of Disorders of the Body; Exemplified by Fictitious Tractors, and Epidemical Convulsions

period treatise · 1800

type:period treatise

year:1800

citation:Haygarth, John. *Of the Imagination, as a Cause and as a Cure of Disorders of the Body; Exemplified by Fictitious Tractors, and Epidemical Convulsions. Read to the Literary and Philosophical Society of Bath*. Bath: R. Cruttwell, for Cadell and Davies, Strand, London, 1800. 39 pp.

LINK

https://wellcomecollection.org/works/qq3tt2yg

SUMMARY

Haygarth's short treatise (originally read to the Bath Literary and Philosophical Society in 1799) reports the first published placebo-controlled trial in the modern Anglophone medical literature. Haygarth had wooden 'fictitious tractors' carved to look identical to Elisha Perkins's patented metallic Perkins Tractors, tested them on five chronic patients at the Bath General Hospital in January 1799, and observed that the wooden imitations produced the same relief of pain and stiffness reported for the real tractors at five times the cost. He concluded that the tractors' effects were attributable to imagination and expectation, not to any property of the metal. Haygarth also reported (this is the nocebo aspect of the experiment, less commonly cited) that a small number of patients had their symptoms worsened by the fictitious tractors. The treatise is the canonical methodological case in the early history of blinded comparison and the founding disconfirmation of the Perkins Tractor.

NOTES

John Haygarth (1740 to 1827) was an English physician trained at Edinburgh, an early advocate of smallpox inoculation, and the originator of fever-ward isolation practice at Chester Infirmary. By 1798 he had retired to Bath. He conducted the fictitious-tractor experiment at the Bath General Hospital in January 1799; his colleague Richard Smith of Bristol Royal Infirmary then performed a confirming imitation-tractor test shortly afterward. Haygarth’s treatise is dedicated to William Falconer (the senior Bath physician) and acknowledges Smith’s confirming Bristol experiment. The 1800 pamphlet was reprinted several times in the early 19th century and is preserved in numerous research-library collections; the Wellcome Collection holds a digitized copy that is the standard reference for modern citation. Christopher Booth’s 2005 biography John Haygarth FRS: A Physician of the Enlightenment (American Philosophical Society) is the standard modern biographical reference. Wootton (2006, pp.155 to 158) treats the experiment as the prototype of placebo-controlled trial design and as evidence that placebo-controlled methodology was available, demonstrated, and ignored for the rest of the 19th century.