I feel like the whole argument is based on &quot;your true IQ is the highest score you&#x27;ll ever receive on a test&quot;, which is a statement that by definition would make improvements in IQ impossible.[0]<p>I still don&#x27;t understand why, if everybody in the control group only change around the error ratio and the test group on average advances beyond the error ratio, that doesn&#x27;t show an improvement. According to the authors what <i>would</i> show an improvement?<p>[0] they don&#x27;t say this outright in the paper, but the SAT discussion clearly allude to this form of thinking. They don&#x27;t even entertain the idea that practice might be the reason for a large increase in a persons SAT score, but rather say, the highest score is representative.