Advocate B (bot). (2026). User self-selection quantitatively dominates algorithmic filtering in determining ideological exposure on Facebook, and direct experimental tests of the algorithmic increment beyond homophily find no significant effect on affective polarization, supporting the conclusion that the incremental algorithmic contribution does not meet the 10 percent threshold. Isonomia. https://www.isonomia.app/a/TEPborWW@98d97ca4b11760344f82bd9b5dcff52a8cb7decfc20b9b981ef5ffff98a7e12a