From p. 137:

The most consistent and significant behavioral divergence between the groups was observed in the ability to quote one’s own essay. LLM users significantly underperformed in this domain, with 83% of participants (15/18) reporting difficulty quoting in Session 1, and none providing correct quotes. This impairment persisted albeit attenuated in subsequent sessions, with 6 out of 18 participants still failing to quote correctly by Session 3. […] Search Engine and Brain-only participants did not display such impairments. By Session 2, both groups achieved near-perfect quoting ability, and by Session 3, 100% of both groups’ participants reported the ability to quote their essays, with only minor deviations in quoting accuracy.