Overnight, it seemed that creativity gurus everywhere were teaching managers how to think outside the box.
Management consultants in the 1970s and 1980s even used this puzzle when making sales pitches to prospective clients.
Speakers, trainers, training program developers, organizational consultants, and university professors all had much to say about the vast benefits of outside-the-box thinking.
It was an appealing and apparently convincing message.
Indeed, the concept enjoyed such strong popularity and intuitive appeal that no one bothered to check the facts.
In the 1970s, however, very few were even aware of its existence, even though it had been around for almost a century.
If you have tried solving this puzzle, you can confirm that your first attempts usually involve sketching lines inside the imaginary square.