The three large null experiments refute the ideological-diversity/echo-chamber pathway to algorithmic polarization but do not address the AA
The three large null experiments refute the ideological-diversity/echo-chamber pathway to algorithmic polarization but do not address the AAPA-amplification pathway identified by Piccardi et al. (2025), which remains supported by only one 10-day study on a single platform.
Guess et al. (2023) randomized 23,377 Facebook and Instagram users to chronological versus algorithmic feeds for three months during the 2020 election and found no effect on affective polarization.
Nyhan et al. (2023) experimentally reduced exposure to like-minded sources on Facebook and found no reduction in affective polarization, ideological extremity, or candidate evaluations.
Guess et al. (2023) on reshares similarly found that removing reshared political content from feeds did not affect polarization outcomes.
Argument from Lack of Evidence (Negative Evidence)