JFK's reaction to being shot seems strange in a couple of ways. Firstly, he doesn't 'clutch' at his throat as one might expect, instead his hands clench into fists which he seems to jam under his chin. Secondly is the way his elbows extend upwards in quite an extreme way. For a second or so he seems to go rigid, his elbows extended upwards. To me this seems more like a reflex than a straightforward reaction to an external stimulus. The difference being that a reflex is quicker than a reaction.
“The average reaction time for a visual stimulus is about 250 milliseconds. The average reaction time for an auditory stimulus is about 170 milliseconds and for a touch stimulus 150 milliseconds.” [https://www.onaverage.co.uk/other-averages/average-reaction-time]
If we assume the average reaction to a touch stimulus is 150 milliseconds we can use this to get a rough estimate of when JFK was first hit. Before that, it must be established when JFK first reacted to being shot. As I stated in an earlier post, as JFK begins to emerge from behind the Stemmons sign (z224) we can see his right hand in a slightly raised position. I argued that, as he was coming to the end of his last wave I couldn't draw anything conclusive about this hand position (ie: he was already reaching for his throat) and that the movement of his left arm/hand was a much truer indication of when he reacted to being shot. It appeared to me that the most obvious reaction began at z226 but there seemed to be a hint of movement at z225. In the clip below i would like to focus on JFK's right hand. It is known that after being shot his hands clench into fists which he thrusts under his chin. The clip below shows the moment his right hand clenches shut into a fist:
It seems clear to me that his hand is beginning to close in z225 and fully closes shut in z226. From this I conclude that his very first reaction to being shot can be seen in z225.
Each Zapruder frame represents, approximately, a timespan of 55 milliseconds. If we accept the reaction time to a touch stimulus as 150 milliseconds this means the stimulus (the shot) cannot have occurred more than 4 z-frames before the reaction. That is to say, the shot to which JFK is reacting cannot have occurred before z221,
particularly if it is a reflex reaction. It is also worth noting that a reflex reaction is much quicker than a normal reaction to a stimulus. As such it can be expected that the first shot hit JFK z221 to z224.
