The participants in Salthouses study were anything but random, and never took into consideration the type of work (cognitive challenging or not) and amount of time in the workforce or whether still in the workforce. A group of doctors and professors might who worked well past legal retirement age might produce a much more varied result then say a group of business people, or factory workers. Although it should be noted that Schooler noted this in her paper and said that her finding were negative for impact of intellectual flexibility.
I also take some issue with the coding for the “cigarette commercial” question posed by Schooler. While points were awarded for the person who could come up with both sides of an argument, and none for the person who could think of no reason, it does little to elaborate for the person who can only give one argument against the commercials seeing that would fit into today’s paradigm that cigarettes are a carcinogen and inherently bad for the user and nearby nonsmokers as well.
Both papers it should be noted are based in cognitive psychology/theory. Relying heavily on scientific modeling and statistical evidence to use as evidence and draw conclusions from, in most all of the statistical models most of the data has been adjusted then sometime readjusted to accommodate multifactorial functions. Something one would not see with Freud, psychosocial studies, or classical conditioning, at least not to this degree and intricacy.
Another idea that caught my attention was that the idea that some cognitive degradation will be camouflaged due to the fact that the aging adult modifies their behavior to overcome or avoid the growing deficiency. This would make it plausible for a type of “micro” black swan theory/event where surround family and friends did not see the ailing person’s disability until some calamitous event, only afterwards were all the signs actually seeable.