Jacob | John Jacob Astor | Jacob M. Appel | Jacob Epstein | Jacob Zuma | Jacob Obrecht | Jacob Lawrence | Jacob Appel | John Jacob Astor IV | Johan Christian Fabricius | Irène Jacob | Jacob Jordaens | Paul Jacob | Johan Galtung | Meshullam ben Jacob | Johan Petter Johansson | Johan Norberg | Johan Niclas Byström | Johan Museeuw | Johan Henric Kellgren | Johan de Witt | Jacob Riis | Jacob Grimm | Jacob Christian Schäffer | Jacob Appelbaum | Johan Jeremiassen | Johan Gunnar Andersson | Johan Cruyff | Johan Bojer | Jacob Truedson Demitz |
These two lines of work came together in the research of Dutch physiologist F. C. Donders and his student J. J. de Jaager, who recognized the potential of reaction times for more or less objectively quantifying the amount of time elementary mental operations required.