When natural instances of such cases are discovered, they often involve children who have been incarcerated in their homes by abusive parents for extensive periods, and have typically involved enormous emotional stressors and dietary impoverishment in addition to environmental deprivation, so don’t make equivalent comparisons. Perhaps the closest human comparison to the life of a typical laboratory rat in the 1940s
is the human prisoner in solitary confinement. (Today’s lab rats are generally housed in environments that include some environmental enrichment like that used by Hebb, Rosenzweig and others. Indeed, the findings from these early studies are largely responsible for this humane change in the treatment of experimental animals.) Even after brief periods in “solitary,” prisoners who do not evince any prior mental pathologies experience long-lasting delirium, impulsiveness, and self-destructive behavior. But such experiences go well beyond a simple restriction of environmental variety. Prisoners in solitary confinement also undergo complete restriction of social stimulation, and this is probably at least as important as the four enclosing walls of the prison cell in producing the deleterious effects of such treatment.9
A better benchmark for the effects of environmental deprivation
on behavior and brain function may come from studies devoted to pinpointing the causes of human disorders such as attention deficit hyperactivity disorder (ADHD). Here, comprehensive studies of the home environment of children have shown that the lack of availability of enrichment in the physical environment of the home, in the form of affordances for play and stimulating wall panels and artwork, is one
of the strongest predictors of the symptoms of ADHD.10 This finding
fits intriguingly well with the results of the Merrifield and Danckert study because the psychophysiological signature of boredom that they identified has also been seen in children diagnosed with ADHD. Collectively, studies of both extreme and more moderate forms of environmental deprivation provide compelling evidence that boring environments can generate stress, impulsivity, lowered levels of positive affect, and an increased likelihood of maladaptive risk-taking
behavior.