In his book showcasing images of life as war raged in Syria, Mr. Katan recounts capturing the video of the boy, Mahmoud, whose older sisters, Asma’a and Nadima, were missing after the airstrike. Asma’a was subsequently confirmed dead. A brother, Muhammad, was carrying a baby sibling, Bayan, whom Mr. Katan likened to a rose because of the red outfit she wore that day, Valentine’s Day.

There is no shortage of photographs and video from Israel and Gaza showing suffering. In Gaza, Israel’s relentless airstrikes have killed more than 8,000 people, according to the Hamas-run health ministry. Overcrowded hospitals and scarce food and water in Gaza have punctuated a dire humanitarian crisis. And Israelis have been burying their dead and live in fear about the fate of more than 200 people kidnapped by Hamas and other Palestinian groups in the October attack.

For some, the misrepresentation and continued circulation of footage from previous tragedies brings to mind the concept of “revictimization,” or forcing survivors to perpetually re-experience their pain.

“There’s a real human right and some deep moral questions, I think, about this kind of thing,” said John Wihbey, an associate professor of media innovation and technology at Northeastern University who has studied misinformation. “As photos of persons who were traumatized or who were in horrific situations recirculate, there is a revictimization or retraumatization.”

Yet such posts — especially those that clearly distill a particular moment — succeed at capturing attention because they appeal to people’s emotions. As the number of victims grows, researchers have found, compassion can begin to fade.

“Narratives can powerfully convey an understanding and emotionality that numbers can’t do,” said Paul Slovic, a psychology professor at the University of Oregon.

Mr. Slovic pointed to a 2015 photograph of a Syrian toddler found facedown on a Turkish beach, washed ashore after the boat carrying him and his family capsized as they sought to flee the war in Syria. Mr. Slovic and his colleagues found that the image was more effective at motivating public response than the grim statistics about the hundreds of thousands who had been killed in the war. In the days after the photo gained widespread attention, Google searches about the conflict and refugees sharply increased, as did donations to a Swedish Red Cross fund, the research found.

But the introduction of misinformation around such stories and visual accounts, Mr. Slovic warned, could give people reason to reject or ignore such evidence more broadly.

Human rights experts have expressed similar worries.

Visual evidence can play an important role in building a case about human rights abuses, said Sophia Jones, a researcher at the Digital Investigations Lab at Human Rights Watch. Verification is critical and a level of skepticism is healthy, she said, but a complete lack of trust carries its own dangers.

“I think it’s absolutely fine to ask questions, and we all should be asking questions. But the lack of trust in anything that we’re seeing I think is problematic because a lot of it is real,” Ms. Jones added. “There are horrible things happening, and those need to be investigated.”

Hwaida Saad contributed reporting.