I will admit that a lot of the confusion alluded to in the title of this post is most likely on my part due to the fact that I look at developmental "age" groups from a psychological standpoint. One of the first classes I taught was a human development class, so any time someone uses the term "young adult," I automatically begin to think in terms of the delineations agreed upon by most developmental psychologists. Unfortunately, these distinctions are apparently not universally recognized by every industry that uses these labels, especially publishing, thus my frustration and confusion. Below are the defined and designated development age groups, as used by developmental psychologists. I am referring to the chronological age only. Each age group is differentiated from the others not arbitrarily, but as a result of years of research indicating a significant difference in the quality (and sometimes quantity) of advancement in each of 4 areas: physical, cognitive, personality, and social development.
Prenatal period: conception (when the ovum and sperm united and the cell begins to grow and divide) to birth (the end of the gestation period, typically 38-40 weeks from conception, when the child leaves the womb). Although the majority of development that has been studied is in the realm of physical development, psychologists are discovering that some rudimentary social and cognitive, perhaps even personality, development also occurs in the womb.
Infancy: birth (day 1, year 0) to 18 to 24 months (usually around the time the child is completely mobile or walking on their own and begins to acknowledge a world larger than themselves). Again, most of the development known is physical development, primarily because it is the most notable. However, many researchers (including Freud, Piaget, and Erikson) have noted other developmental milestones in this age range in social, cognitive, and personality realms.
Toddlerhood: 18-24 months to 4 years (about the time the child enters a pre-k program in most states in the US). This time period represents additional physical development, especially increased coordination and mastery over the major muscle groups. Cognitively, children begin to expand their understanding and curiosity about the world. They are also evolving socially, recognizing that they might not actually be the center of the universe, as they previously believed. Personality is shaped through social interaction and experimentation with the natural and imaginary worlds.
Middle childhood: ages 5 years to 11 years, or the "elementary school" years. I believe some authors and publishing houses are starting to call this age "mid-grade," but as I am not in publishing, I am uncertain. From a developmental standpoint, children continue to grow physically, though not as much as in the next phase. Also, as their cognitive development progresses, they not only learn new facts, but also begin to understand different viewpoints, which aids in their social and personality development.
Adolescence: Ages 12 years to 19 years, also know as the teen years, or the middle-school/high school years. My limited understanding of the publishing industry has led me to believe that this is the age group tentatively designated as "young adult." If this is correct, then I am completely confused about this misnomer, as Young Adult in developmental psychology is a completely different age group. Developmentally speaking, adolescence represents that last great period of physical growth, culminating in the growth spurt(s) associated with puberty. Cognitive development sees an introduction of the ability to see the world abstractly and hypothetically. Social and personality development are the greatest focus of research for this age group, as these seem to be the areas in which an individual will experience the most significant differences from start to finish.
Young Adulthood: Ages 20 years to (roughly) 39 years, also known as Early Adulthood to some developmentalists. In publishing, it seems as if this is a newer subdivision, known as "New Adult." Again, I'm a psychologist, not an author or publisher, so I am not fully versed in this area. What I do know, from a developmental psychology perspective, is that young adult means the 20s and 30s in life. Individuals reach their peak physical abilities during this time and their cognitive abilities continue to expand and specialize. Not too much research (compared to previous age groups) has been conducted on the social and personality develop during this age, though developmental psychologists are recognizing that this time in one's life does represent certain challenges and expectations that are not seen in previous or subsequent years. However, we see societal influences grow in greater importance during all of the adult years, as variations between individual behaviors and expectations tend to increase between cultures with adult subjects. I think that part of the reason research is more scant from a developmental view is that we take for granted that all "adults" are alike--i.e. have the same expectations placed upon them--once they reach the "magic" stage of adulthood.
Middle Adulthood: Ages 40 years to 60-65 years. I have noticed that publishing seems to treat the rest of adults the same way in that they no longer make any distinctions about age of characters or life situations once the adult threshold has been passed. Developmentally, we see a gradual decline in physical abilities, though cognitive abilities may continue to increase or at least stay static. Social development takes on new meaning as different expectations and roles are faced in this life stage. Personality development is believed to also stay mostly static, yet some minor tweaks may occur if the right experiences come along.
Late Adulthood: Ages 65 years and older. Again, there seems to be no distinction here in the publishing industry. Developmental psychologists study life from the womb to the tomb, however, so they do have an interest in changes that occur as we continue to age further. Despite stereotypes, cognitive abilities reach a plateau (at least fluid intelligence does; crystallized intelligence continues to increase), they do not decline in late adulthood. Physical development continues its decline. This may be more rapid for some and slow for others, depending upon their general health throughout their lifespan. Social development revolves mostly around cultural expectations for individuals at this stage. Some cultures value the wisdom and experience of age, some feel older individuals should be neglected because they have moved beyond their usefulness. Personality development will be greatly influenced by this social development.
My Confusion with Publishing Labels
The beginning of my confusion when it comes to authors and/or publishers trying to label their stories comes from the qualifications necessary to place a story in a particular reading age group. Perhaps someone can answer this for me. What makes the book "mid-grade" or "young adult" or any other age-related designation? Is it that the characters fall within this age group, or that the language is at this cognitive developmental level, or that the subject matter is at this social development level expected in that particular age range? Have publishing houses actually looked at the research to determine that the book is written in the language level appropriate for the cognitive development for the stage, if it is based on comprehension level? If it is based on just the age level of the main characters (or simply the majority of the characters), then there might be quite a few books that may need reconsideration in their age designation. And what happens if the characters progress from one age level to the next? Does some of the series then fall into the next category? I'm sure that would cause some confusion for book stores and libraries, as they have also separated their juvenile (or children's) sections into varying age groups, specifically distinguishing between young adult, juvenile, easy reader, and (sometimes) teen. If the books are placed in a particular designation because of the social developmental level, I wonder if publishing houses have done their homework to determine that the characters are facing appropriate age-related social challenges to garner the distinction given.
I am not trying to reformat the publishing industry. I am pretty sure that if anyone actually reads this post they might take offense at my questions, misinterpreting my purpose. I am truly confused and curious as to how these (to me) sometimes arbitrary age-related labels get slapped onto a book or series. I can tell you from personal experience that it doesn't always guarantee more or fewer readers. Many full-grown adults will read "children's books" if the story is well-written and the characters are personable. I think it is misleading to label something in the hopes of getting a larger audience--much like movie studios do when they vie for a particular rating in order to encourage or discourage a certain population from seeing it. Believe it or not, the public (possibly in error) trusts industries to be honest with them when categorizing their offerings. Placing a book--or a movie, television show, video game--in the wrong category can create unnecessary anxiety, especially for parents who want to make sure that their children are exposed to age-appropriate content. That anxiety can also be felt by others who fear ridicule and harsh judgment from their peers for reading (or watching or playing) content that is supposedly developmentally below their current stage.
Hopefully, I have enlightened a few people about the current age-related distinctions that those who research developmental stages use to determine when an individual has transitioned from one age group to the next. Perhaps I have even started some person on the road to understand why one child may be considered developmentally delayed in one of the four categories. I, myself, am also looking for enlightenment in those areas with which I am not fully inducted so that I can continue to grow and learn on my life journey.