Roberto Ardigò as a forerunner of George M. Stratton's experiments on inverted vision

After Johannes Kepler's supposition of inverted and reversed retinal images and Christoph Scheiner's anatomical demonstration of such an inversion, the question arose whether this inversion is necessary and how it is possible to see an upright world based on an inverted image. The answer to this question is commonly attributed to the American psychologist George M. Stratton, who produced, in 1896, upright retinal images by means of lenses and showed that after a phase of inverted perception, upright vision is restored. However, prior to 1886, the Italian philosopher Roberto Ardigò had already performed optical experiments with a prism, obtaining a similar result. The intend of his optical investigation was essentially psychological, in opposition to contemporary physiological approaches. He accepted Hermann von Helmholtz's basic assumptions, but interpreted the results of his experiments in the framework of a more detailed theory of perception. The present article aims to analyze Ardigò's experiments and compare them with Stratton's in order to give them the place they deserve in the history of experimental psychology. (PsycINFO Database Record (c) 2020 APA, all rights reserved).