Twitter locks scientist's account after he quoted new Stanford study proving mask-wearing is ineffective: Twitter locked cognitive scientist Mark Changizi's account after he quoted a recent Stanford University study claiming masks are ineffective and harmful. Quoting the conclusion of the study, Changizi tweeted "The existing scientific evidence challenge the safety and efficacy of wearing facemask as preventive intervention for COVID-19.” Twitter claimed the tweet violated its "policy on spreading misleading and potentially harmful information related to COVID-19" and locked his account for 12 hours. Locked accounts can typically use direct messages and browse the platform but cannot tweet, retweet, like other tweets or follow new accounts.