No one, that is, before two different research teams—Clarke Burnham with Kenneth Davis, and Joseph Alba with Robert Weisberg—ran another experiment using the same puzzle but a different research procedure.
Both teams followed the same protocol of dividing participants into two groups.
The first group was given the same instructions as the participants in Guilford’s experiment.
The second group was told that the solution required the lines to be drawn outside the imaginary box bordering the dot array.
For example, there have been some theories such as those of Schopenhauer (see his remarks about Genius) and Freud (see his remarks about Sublimation) that propose creativity is something more like a capacity provided by nature rather than one acquired or learned from the environment.
Indeed, the concept enjoyed such strong popularity and intuitive appeal that no one bothered to check the facts.
He challenged research subjects to connect all nine dots using just four straight lines without lifting their pencils from the page.
Today many people are familiar with this puzzle and its solution.
It's an interesting experiment, but the author's conclusion cannot possibly follow from the results of it.
your conclusion: that the second experiment disproves the theory that thinking outside the box is useful in solving problems, is itself a fallacy.