Since mid-August, the Islamic State has released three execution videos of three Western hostages. We're all sadly familiar with these brutal productions, but what strikes many is how collected and articulate the victims are while giving their final speeches denouncing their home governments. Why weren't they terrified? Why didn't they fight back? I admit I have no idea how I would have composed myself facing imminent death.

But after watching many of these types of videos, here are three points that might explain why James Foley, Steven Sotloff and David Haines gave the propaganda speeches they did.

The hostages may not have known they were to be murdered. There's something odd about all of the Islamic State's productions: They never show the hostage actually being killed. Rather, the video always cuts away right before the deed is done. This suggests that the hostages didn't realize they were about to be killed.

This might have been on purpose. In the past, the Islamic State's predecessors had no compunction about telling many of their captives of their impending end. In these videos from the Iraq war, some hostages seem to be in a catatonic trance, meekly awaiting their fate. But the few that gave speeches before their beheading were at their wit's end. I recall one hostage in particular who begged at length for his life on his video; his killers showed him no mercy. It was awful to watch, though I had to for my job as a CIA analyst.

Yet others remain defiant even up to the end. In 2004, an Italian security contractor in Iraq named Fabrizio Quattrocchi, captured by the Army of Islam, yelled, "I'll show you how an Italian dies!" and tried to remove his hood right before being shot.

But those individuals unambiguously knew the end was coming. For the Islamic State's more recent Western victims — the composed interviewees we see on tape — they simply may not have known what was going to occur, which allowed them to remain articulate and compliant in their final hours.

Even if they suspected they'd die at some point, they were under enormous pressure to comply with their captors. Remember that these hostages had been in captivity for many months, suffering both physically and psychologically. Of the Islamic State's three Western victims, Foley had been a hostage since November 2012, Haines since March 2013 and Sotloff since August 2013.

These men were undoubtedly treated with great cruelty and threatened with death numerous times. We know this because one French journalist held with James Foley said he had to endure several mock executions. Further, John Cantlie — who has recently resurfaced in another Islamic State video — had been a hostage in Syria beforehand, being held by a group of jihadists who blindfolded, hooded and frequently told him they wanted to kill him. Chances are the three beheading victims were held in similar circumstances.

These extreme conditions can take a terrible toll on a person's emotional well-being. As such, the hostages might have thought making pro-ISIS speeches were yet another indignity they had to endure. They might have also taken heart knowing that viewers would see the messages as clearly coerced. The most famous Vietnam War era prisoner message, for instance, featured Cmdr. Jeremiah Denton, who had to submit to a propaganda film on behalf of North Vietnamese captors in 1966. He showed great tenacity by blinking the word "T-O-R-T-U-R-E" with his eyelids in Morse code.

The hostages might have known the end was coming, and accepted it. But this is the least convincing of all the explanations. Both Foley and Sotloff speak of their own deaths in an abstract way, and the last hostage, David Haines, explicitly discusses his impending execution. Given the rehearsed, calm nature of their speeches, however, this does not seem especially likely.

Hostages rarely, if ever, speak their true thoughts in propaganda films and videos. (Denton, who defended U.S. policy and paid for it with years of beatings, was a rare exception.) Otherwise, it undermines the purpose of turning out propaganda in the first place, which is to disseminate a message and advance a political cause. If the three men were calm in their speeches, it's not because they were actually at peace.

- By Aki Peritz

Peritz is a former CIA counterterrorism analyst and coauthor of "Find, Fix, Finish: Inside the Counterterrorism Campaigns that Killed bin Laden and Devastated Al Qaeda."