I think we really need to distinguish between perceived effect and physiological impairment that is a function of physics and biology. I have no doubt that different people perceive different effects and that these change from day to day and are as variable as the wind ..... Arguing about someone's ability to "tolerate" narcosis is akin to arguing about someone's ability to tolerate alcohol ..... We are talking about a physiological reaction to increased partial pressure of gases. Period. This is science. Narcosis is impairment. Period.
When you express yourself so clearly I'm forced to disagree with you. What we are concerned with, whether diving or driving a car, is ACTUAL impairment, which relates to the psychological state, not the physiological one.
It is well known that some people can tolerate alcohol much more than others, and that an alcohol level which will render one person a danger to everyone on the road will have no negative impact at all on another person. Indeed, some people (possibly alcoholics) require a certain level of blood alcohol to function properly. The only reason there are absolute limits is for ease of enforcement, nothing more.
If a diver can function normally at a certain pPN2 whereas another cannot, why should the first diver have to abide by the limit that the second diver needs? The Mount study showed that there really is a considerable placebo effect in narcosis, and it wasn't used as a way to skew the results. Anyone who knows Tom Mount knows that he is very much an advocate for the use of helium when appropriate - he's not trying to persuade people to dive deep on air the way Hal Watts used to.
As to your last statement in that paragraph "We are talking about a physiological reaction to increased partial pressure of gases. Period. This is science. Narcosis is impairment. Period." I'm afraid you are seriously mis-stating what science is. Science is NOT a statement of indisputable facts - it is a
process of observing facts, attempting to construct explanations (theories) to support those facts, and then testing those theories. There is nothing absolute about science. In your case, you are stating your premise as a given ("We are talking about a physiological reaction to increased partial pressure") and then deriving it. Small wonder that you appear able to prove your case.
The point is that we are
not concerned with a physiological reaction but a psychological one, as that is what governs our behaviour. There are objective measures of people's performance (handling puzzles, etc) and people vary greatly in their ability to do these at depth. I have students who seem significantly impaired at 100', and others whose performance doesn't seem to change as far down as 170' (I've not tested students on air below that depth). I have regular dive buddies who appear totally
compos mentis at those depths, and I know both from how I feel and from what others say that I function normally. This is in warm clear water - I would want to re-evaluate in different conditions. The scientific process, in fact.
Diving is a very new sport, and much of what is going on is not yet understood. Narcosis is certainly one of those inadequately researched areas. I don't object to you or anyone having your own ideas about what's going on down there, and determining your own behaviour accordingly. But please don't construct specious arguments to give your ideas unwarranted credibility and impose them on others.
Sure would have a lot of extra money in my bank account though............
