[2] One of his ultimate goals was to use the scientific method to identify truth from error, and educate the general public, which Jastrow accomplished through speaking tours, popular print media, and the radio.

[1] During his doctoral studies at Johns Hopkins University, Jastrow worked with C. S. Peirce on experiments in psychophysics that introduced randomization and blinding for a repeated measures design.

[1] Jastrow was head of the psychological section of the World's Columbian Exposition in 1893,[7] where he collected "psychophysical and reaction time data" from thousands of attendees.

[1] Jastrow was noted for his outreach in popular media, making psychological research accessible to a wider audience.

[18] In his book The Psychology of Conviction (1918) he included an entire chapter exposing what he called Eusapia Palladino's tricks.

[20] His book Fact and Fable in Psychology (1900) debunked claims of occultism including Spiritualism, Theosophy and Christian Science.

[23] He wrote that many people considered coincidence, dreams, and premonitions as sources of information above science,[24] and said the role of the scientist was to help the public understand truth from fiction, and to prevent the spreading of erroneous beliefs.

"[28] He wrote about cultures that ate animals to gain their physical attributes;[29] he said this tradition still persisted in his day, through superstitions, rituals, and folk medicine.

He thought that eyesight was more complex than a camera, and that the mental processing of images was central to interpretation of the world.

[41] As early as 1913, at the congress of the German Psychiatric Association held in Breslau, Joseph Jastrow criticized psychoanalysis as unscientific and pseudoscience.