Bloody attacks and midnight arrests, combined with a regime growing more technologically savvy, have begun stemming the flow of online information from dissidents in Iran, activists and human rights officials say. Once emboldened by their ability to dodge the government and spread news about their protests to the world, many in the youth-driven protest movement, they say, are now scared of the consequences of getting caught. “It’s absolutely chilling,” said Drewery Dyke, a member of human rights group Amnesty International’s Iran team. “The level of fear that has permeated society now, in terms of this issue, is palpable. It’s striking. “There’s an absolute hunkering down by the people.” Since June 12, when disputed election results sent tens of thousands of Iranians into the streets to protest, the world has gotten a front-row view of the unrest thanks largely to dissidents using online tools to spread the news. But as days have turned to weeks, there’s been a sharp drop in the number of messages, pictures and videos that supporters outside the country have been receiving.