Peter Gamma from www.petergamma.org supposes that such studies started after Richard Davidsons PNAS paper was published in 2004: https://pubmed.ncbi.nlm.nih.gov/31004219/ For instance: 2. DC Rainmaker with sports watches. 3. Hugo Plácido da Silva with BITalino 4. William Croft with OpenBCI 5. Rob ter Horst with the devices he studies: 6. Ildar Rakhmatulin with PiEEG at Heriot-Watt …