These two correlations do not by themselves prove that chronic stress damages the memory, but Dr Evans and Dr Schamberg then applied a statistical technique called hierarchical regression to the results.
Albert Pinkham Ryder and Morton Schamberg, much talked about in 1913, are absent, as is Kuhn's important contribution called "Morning, " while several lesser works have been unearthed that should have remained buried.
So, it may not be necessary to look any further than their place in the pecking order to explain what Dr Evans and Dr Schamberg have discovered in their research into the children of the poor.
Dr Evans's and Dr Schamberg's study does not examine the nature of the stress that the children of the poor are exposed to, but it is now well established that poor adults live stressful lives, and not just for the obvious reason that poverty brings uncertainty about the future.