We have made a long journey from the reaction time experiment, in which Franciscus Donders (1868/1969) determined how much time is needed to make a decision.

But now that you have reached the end of the book, let us allow ourselves to imagine something magical – Donders is given the opportunity to visit a 21st-century cognitive psychology laboratory.

When Donders enters the lab, he marvels at the technology, especially the computers and the brain scanner. After observing these developments, however, he turns to the lab director and says, “Wonderful technology, but what I really want to know is whether you have found a way to measure the function of the mind directly.”

The lab director replies, “Ah, no. We measure behavior and physiology and infer what is happening in the mind.”

“Ah,” says Donders, “so the technology has changed, but beyond that, nothing is different. The study of the mind still involves indirect measurements, assumptions, and inferences.”

“Correct,” says the lab director, “but let me tell you what we have discovered since 1868…”