"Publishing giant Pearson recently conducted an experiment involving more than 9,000 unwitting students at 165 different U.S. colleges and universities"

EW:

Without seeking prior consent from participating institutions or individuals, the company embedded "growth-mindset" and other psychological messaging into some versions of one of its commercial learning software programs. The company then randomly assigned different colleges to use different versions of that software, tracking whether students who received the messages attempted and completed more problems than their counterparts at other institutions.

Related:

A few years after the Second World War, Muzafer Sherif conducted possibly the most complex field studies ever attempted in social psychology. Sited in summer camps around the United States, they focused on conflict and cooperation within and between two groups of about a dozen 11- and 12-year-old boys. The children were never informed that they were taking part in research. In each study, Sherif and his fellow researchers spent up to three weeks disguised as counsellors and caretakers, manipulating features of the camp set-up — in particular, the structure of team competitions and challenges — to examine their impact on group relations.

In The Lost Boys, Gina Perry puts these extraordinary experiments under the microscope.