I just finished reading this book and it was wonderful. I am not going to summarize it here, but instead talk about the thoughts it raised in my mind.
First, he mentions a couple of phases that prisoners went through in a concentration camp. The initial phase was shock, followed by apathy, and finally reactions of depersonalization if liberated.
I could not help but draw a parallel between his phases of prison camp psychology and that of two other theories: Taylor's theory of cognitive adaptation and Selye's General Adaptation Syndrome.
Taylor explains man's response to threatening events by positing that cognitively adaptive efforts are made to search for meaning, gain mastery, and attempt to enhance the self.
Selye's research showed that in response to an interruption of physical homeostasis, the body reacts predictably also going through three stages: shock, resistance, and finally exhaustion.
Selye's is actually the most useful of these three outlooks on stressful events as it is the most general and biologically rooted, giving strong hope for a biological explanation of the two psychological theories generated by Frankl and Taylor. I believe that both Frankl's initial phase of shock and Taylor's threatening events are essentially the first phase of Selye's adaptation syndrome. They both work as initial stresses.
After this first phase of shock in all three theories comes resistance. In the case of the Frankl's psychology, the prisoners attempt to resist the shock of concentration camps with apathy. Taylor on the other hand believes people's first resistance is a search for meaning, which Frankl gets to later and discusses throughout his book as well.
Finally, Frankl saw that many prison camp survivors were unsuccessful in finding meaning and fell into a state of depersonalization or moral deformity upon being released from a camp. This represents a lack of success in generating resistance during Selye's second stage and results in psychological exhaustion. Taylor on the other hand explains successful resistance in stage two with an enhancement of the self. This is a successful psychological adaptation to the event and exhaustion does not ensue.
I hope that at some point in the future, psychology is able to take a page from Selye's work in endocrinology and recognize that much of what they attempt to explain using psychological models is already easily explained with the General Adaptation Syndrome. People's successful resistance to their initial shock is a result of the interdependence of their genes and environment which can lead to either personal growth in the form of positive adaptation or a decline in health due to maladaptations or exhaustion.