It was an appealing and apparently convincing message.
Guilford was one of the first academic researchers who dared to conduct a study of creativity.
Most people assume that 60 percent to 90 percent of the group given the clue would solve the puzzle easily. What’s more, in statistical terms, this 5 percent improvement over the subjects of Guilford’s original study is insignificant.
In other words, the difference could easily be due to what statisticians call sampling error.
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.
Even though they weren’t instructed to restrain themselves from considering such a solution, they were unable to “see” the white space beyond the square’s boundaries.