1. The Normal Child Locked Inside Model
Originating with Bruno Bettelheim (The Empty Fortress), this model holds that locked inside every autistic child is a normal child and that sufficiently drastic changes to his or her environment, including sufficiently intensive therapy, can unlock this child.
In Bettelheim's day, the favorite cause of autism was "refrigerator mothers" who had willed their child's non-existence, and what would unlock the normal child was Freud-inspired psychotherapy, along with removal of the child from his or her parents.
Later, blame was lifted, somewhat, from mothers, and the intensive therapeutic remedies morphed into some combination of play based therapy (e.g., Floor Time) and behaviorist therapy (e.g., ABA). While professionals no longer claim that these therapies can unlock a fully normal child, bestselling miracle cure books by parents (Let Me Hear Your Voice; The Boy Who Loved Windows) claim otherwise. Some locked-in children may also be partially liberated by assistive communication devices like keyboards or a Dynavox.
More controversial remedies for locked-in children include Facilitated Communication (The Mind Tree), whereby previous mute children, via a keyboard and a supportive hand from a highly trusted companion, apparently express complex emotions, empathy, and subtle (if quirky) humor, perhaps in sophisticated prose and/or poetry.
The locked-in child version of autism best describes those whose autistic-like symptoms are caused either by some sort of withdrawal-inducing sensory overload, or by a serious impairment in fine motor control (e.g., apraxia) that makes speaking, gesturing, and controlling eye gaze difficult or impossible. Help the child regulate his intake and processing of sensory information, or supply him with assistive communicative devices, and a socially normal personality may start to emerge.
2. The Brain Injury Model
This model holds that some kind of brain damage/abnormal brain development is responsible for autism--usually pre- or perinatal, for example, German Measles--that may be deep enough that there is no longer a normal child inside and that restoring full or partial normality can only be achieved, or restored, via drastic measures. Specific recent theories about causes include the dysfunctional mitochondria theory (causing deficiencies in the fueling of neurons), theories about problematic in utero environments (the parental age theory; the close birth spacing theory) or insufficient time spent in an utero environment (the premature birth theory).
More popular with lay people is the discredited vaccine injury theory, which first indicted the MMR vaccine for its live measles virus (which, it is imagined, induces a "leaky gut" that then allows "opioid-like" gluten molecules to enter the brain and stupefy it), and then vaccines in general for their mercury (Unraveling the Mystery of Autism and Pervasive Developmental Disorder; Evidence of Harm).
No responsible medical professional has proposed cures for autism-related brain damage; pet remedies of the vaccine injury proponents include the Gluten-Free Diet and Chelation (the highly dangerous and ineffective process of removing heavy metals from the body). Much safer, effective remediations, again, are tried and true therapies like ABA. Specific remedy aside, the idea here isn't to unlock a normal child, but to reverse the damage, bypass damaged circuitry, and/or or teach the child ways to compensate, "habilitate," or pass as normal.
The brain injury model best fits those whose autism includes not just social impairments, but cognitive impairments, linguistic impairments that are unrelated to social impairment, and/or impairments in sensory processing and self-regulation.
3. The Quirky Personality (or Extreme Maleness) model
Popularized by Simon Baron-Cohen (The Essential Difference), this model holds that autism is caused by excess exposure to testosterone in the womb, and/or by "assortative mating" in which highly unsocial, analytical people are more likely to find one other in today's interconnected world, to intermarry, and to produce even more extremely unsocial, analytical offspring (concentrated in areas like Silicon Valley).
This model best explains those children whose primary deficits are social, and who excel in things like engineering and computer programming: the Temple Grandins of the world. Some of those who embrace this type of autism have argued against intensive treatments (beyond helping the child with basic social skills). In this view, AS is just another personality type, and why should the burden be primarily on the child, rather than on the rest of society, to make the necessary adjustments?
Reconciling the models?
Different specialists don't seem to spend a lot of time reconciling their particular autism model with others. Depending on who you read, or what kind of child you have, either a more normal child is waiting in the wings; or a once potentially normal child was neurologically damaged; or there never was a normal child in the first place, but why worry?
Looking at my son, I wonder if all three might somehow be true.