I just did a quick search on Pubmed for "childhood emotional neglect" and 98 results came up, which is not a lot but not nothing either. For me, the concept helped me understand my experience and my maladaptive thoughts/coping strategies, and it gave hints about what to examine more closely with my T. The emotional neglect concept doesn't totally come out of nowhere either because it has underpinnings in attachment theory, child development, research on parenting styles, etc, which are all more established. It is more or less a way to take somebody who appears in therapy with certain issues but without specific events that might explain them more easily. As the book says, it's the blank spaces in the family photo.