The Isolator by Hugo Gernsback, as it appeared on the cover of, and the pages in between, the July 1925 issue of Science and Invention.
While Attention Deficit Order, with or without hyperactivity, isn’t mentioned (it didn’t exist as a diagnosis back then), The Isolator was designed to help focus the mind, particularly when reading and writing (literacy is hard work!). The helmet not only eliminated all outside noise, limited sight to just one line of text at a time, but it also pumped in oxygen. From the looks of it, the contraption would also assist in limiting hyperactivity by limiting movement, or, between weight and limited visibility, it would at least slow you down.
Via A Great Disorder and 50 Watts. At Boing Boing, Mark captions the mag cover “Portrait of a Blogger in the 1920s.”
Wow is that thing creepy! Poor kids I’ll bet it was like torture!