JFK Assassination Forum

Your whole premise is based on the assumption that these head movements were all cause by the same stimulus and that stimulus was Oswald's first shot. That doesn't seem very compelling proof to me of a shot at virtual Z124. I'd also like to know how you pinpointed it at the instant. I've explained how I have arrived at my conclusion the first shot was fired at Z148. Maybe you have explained it before but I'm not going to search the archives to find it. It would be a needle in the haystack for me to do it. Please give us the Reader's Digest version of how you reached your conclusion as to the specific time of the first shot.

ME: Explain in 100 words or less how Roselle and Scearce determined that the first, missing everything, shot occurred about half-a-second before Zapruder resumed filming at Z-133.

Thought for 7s

GROK: Roselle and Scearce (2020) used human reaction-time science on the silent Zapruder film to time the first (missed) shot.

acsr.org

They distinguished fast involuntary startle reflexes (e.g., ~0.06–0.2 sec flinch) from slower voluntary “surprise” reactions (conscious head turns/looks to locate the sound source). Using brake perception-reaction time (PRT) models from traffic studies—adjusted for total surprise—they estimated median perception time to initiate voluntary movement at roughly 0.5–1+ sec (varying with expectancy).

https://d7922adf-f499-4a26-96d4-8ab2d521fa35.usrfiles.com/ugd/d7922a_e280e26982b44f2c97c6e6e27026e385.pdf

In early frames, they identified near-simultaneous voluntary reactions by 7 witnesses (JFK, Jackie, the Connallys, Kellerman, Hickey, Rosemary Willis) starting ~Z140–Z150 (e.g., rapid leftward head turns then right). Subtracting typical surprise PRT placed the gunshot sound ~½ sec earlier—at hypothetical Z-124, just before Zapruder restarted filming at Z-133 after his ~17-sec pause.

jfk-assassination.net

This fits eyewitness timing, earwitness patterns, and a pre-tree miss. (≈85 words)

Please tell me in 100 words or less how Roselle and Scearce determined that the first, missing everything, shot occurred about half-a-second before Zapruder resumed filming at Z-133.

Thought for 7s

Roselle and Scearce (2020) used human reaction-time science on the silent Zapruder film to time the first (missed) shot.

acsr.org

They distinguished fast involuntary startle reflexes (e.g., ~0.06–0.2 sec flinch) from slower voluntary “surprise” reactions (conscious head turns/looks to locate the sound source). Using brake perception-reaction time (PRT) models from traffic studies—adjusted for total surprise—they estimated median perception time to initiate voluntary movement at roughly 0.5–1+ sec (varying with expectancy).

In early frames, they identified near-simultaneous voluntary reactions by 7 witnesses (JFK, Jackie, Connallys, Kellerman, Hickey, Rosemary Willis) starting ~Z140–Z150 (e.g., rapid leftward head turns then right). Subtracting typical surprise PRT placed the gunshot sound ~½ sec earlier—at hypothetical Z-124, just before Zapruder restarted filming at Z-133 after his ~17-sec pause.

jfk-assassination.net

This fits eyewitness timing, earwitness patterns, and a pre-tree miss. (≈85 words)

. . . . . . . .

I know you love jiggles, John Corbett, so just for giggles I'd like to share with you what someone by the name of Herb Huskr just posted:

Three synchronized film clips shown together in three different montages:

1) Elsie Dorman

2) Secret Service reenactment

3) Zapruder clip

These are shown with dubbed-in gunshot sounds at:

Montage 1:  "Z-107," Z-219, and Z-310

Montage 2:  "Z-124." Z-219, and Z-310

Montage 3: Z-160, Z-219, and Z-310

When we watch and listen to montage 2, we see that Dorman, who at a distance of 35 feet was subjected to about 135 dB from the muzzle blast of Oswald's Carcano (whereas Zapruder, at 275 feet, was subjected to only about 119 dB, and Phil Willis at 130 feet was subjected to 125 dB), was so startled by the sound of the first shot at "Z-124" that she stopped filming altogether (her finger slipped off the button). Then she resumed filming a couple of seconds later and at approximately Z-219 jiggled her camera like all get out and stopped filming again. Interestingly, she doesn't jiggle her camera at all at Z-310. Could it be due to her having become habituated to the nearby muzzle blasts? Seems logical to me.

https://www.facebook.com/groups/553546571932211/user/100003268844965

The survey data at CE884 puts the Kennedy to Rifle distance 218.0 feet at z255 and 265.3 feet at z313. That means that he travelled 47.3 feet in 58 frames. At that rate at z271 JBC was 233 feet from the rifle. At 2000 fps that means the trigger was pressed about 233/2000=116.5 ms earlier.

Since it's survey data, I doubt it took into account the elevation. Adding the elevation increases the distance.

For the shot that struck at z313 when JFK was 265.3 feet from the rifle, the trigger would have been pulled 265.3/2000=133 ms earlier.

So we are talking about a difference of 16.5 ms or .0165 of a second

Since the exposure time of Zapruder’s camera was 1/40th of a second or 25 ms., there was 30 ms of non-exposure between frames.

It's a miniscule difference but since your data doesn't take into account elevation, it becomes even less relevant.

You are correct that there is a gap between each frame of the film when the camera isn't recording.

When I say z271-272 I mean the shot occurred at some time either very late during the exposure of z270 up to very early in the beginning of the exposure of z272.  Since the time between frames is 1000/18.3=55 ms, that provides a range of the time of the shot of 55+30=85 ms. The head shot could have occurred very late in the exposure of z312 to the middle of the exposure of z313.  That is about 45 ms. Total uncertainty is 130/2=65 ms=.065 sec.

So the time difference t between trigger pulls between the second shot striking JBC at z271-272 and the third shot striking JFK at z312 to z313 a distance of 32.3 feet farther from the rifle is:
t=(312-270)/18.3-(32.3/2000)  ± .065 seconds

t=(42)/18.3-.0165 ± .065 seconds

t=2.28  ± .065 seconds or 2.22 to 2.34 seconds

Even with your tweaking, you don't bring the time between shots to what the FBI determined was the minimum time needed to fire an aimed shot. Even that is a theoretical time, it's very unlikely Oswald would have tried to fire the rifle as fast as he could. Accuracy would be far more important than speed. That's why he took almost 5 seconds between the second and third shots.

Certainly. Hickey just said that JFK’s hair flew up at the moment he heard the second shot. There could have been movement of the air caused by something other than the bullet.  But that wouldn’t alter the observation that the hair flutter-which occurs at no other time-coincided with the sound of the second shot.  But I don’t see the hair of anyone else move.

What Hickey says doesn't establish the bullet caused his hair to fly up. The bullet would have arrived before the sound because the bullet was traveling almost twice the speed of sound.

The Warren Commission found that a minimum of about 2.3 seconds was required to fire, reload aim and fire again using Oswald’s rifle. This appears to be based on the FBI re-enactment using that rifle. FBI ballistics expert Robert Frazier, who actually fired 3
shots in 4.6 seconds, said “4.6 seconds is firing this weapon as fast as the bolt can be operated, I think”. (3H407). The FBI’s Ronald Simmons noted that one marksman fired three shots in 4.6 seconds using the telescopic sight and three shots in 4.45 seconds using the iron sights.(3H446). There was no time placed on the middle shots so we cannot determine the smallest interval between shots.

Why would you think Oswald was would try to fire his rifle as fast as was humanly possible? Was he trying to win a prize?

How damn stupid are legacy media reporters. I'm going to paraphrase this since I can't quote him word-for-word. Wolf Blitzer just said that he was just a short distance away when the "alleged gunman" was taken down by the Secret Service. If he saw him do it, why is he saying it's an alleged gunman. Does Wolf need confirmation to report what he saw with his own damn eyes. What an idiot.