More on Toilet Training

  • When can we expect readiness and training?

Widespread acceptance of readiness and independent toileting have since been supported by clinical experience and resulted in agreement that a child should be ready to participate in toilet training at approximately 18 months of age and be trained completely by 2 or 3 years old. Global trends continue to support this concept despite technologic advancements and conveniences such as diapers, which have enabled delayed training. Source: Pediatrics
The chronologic disparity between initial success and toilet mastery may be reflected in the fact that parents tend to misjudge the age at which a child completes training as well as the amount of time required for toilet training (which averages 5.8 months and 6.4 months for bladder training in females and males, respectively, and 6.3 and 6.9 months for bowel training). Source: Pediatrics
It is a pleasure to read that Azrin and Foxx "provided pediatricians with additional empirical standards for tracking a child's progress toward toilet mastery" when they identified empirically two components of toilet training readiness, which they called physiologic and psychological. Physiologic markers include sphyncter control and muscle tone:
"...control over bladder contractions and the external urinary sphincter. "Bladder-ready" toddlers therefore void large amounts at a time, remain dry for several hours at a stretch, and are aware of their need to void.""...sufficient muscle tone to carry out the physical components of independent toileting, ie, the ability to walk from room to room, pick up small objects, get dressed and undressed, and sit upright for 5 to 10 minutes at a time."
Psychological variables involve the called cognitive abilities that Foxx and Azrin described as observable behaviours:
"...observing whether a child can perform at least 8 of 10 predefined simple actions on command. Some of these actions include pointing to body parts; sitting, standing, and walking to a particular place with a caretaker; imitating a simple task; and manipulating familiar objects in a designated manner. This was the first use of objective criteria that parents could use to observe their children in determining readiness for toilet training." Pediatrics
I recommend not over worrying about the pointing to body parts! And having the child's doctor clear for toiling / investigate if there is anything medical that should be known or should be treated or considered before toilet training.

Children's maturity and mastery of such markers vary too greatly to allow a simple readiness test or guarantee that everything will go smoothly if the mentioned variable have been achieved. To complicate matters, children with autism may be "all over the place" with their maturity and skill mastery across areas of development. So we are on our own so to speak and experience will help dramatically, professional out there. And parents, you can count on experienced professionals to help. 
It can be reasonably expected that children will not show a desire to cooperate or an ability to play an active role in achieving toilet training until they are at least 15 to 18 months old. However, there may be signs that a child has not begun to attain bladder and bowel control*1 and that an attempt to toilet train is probably premature regardless of age.  
If a child is not ready for toilet training by age 20 months, one practical approach is to wait an additional 3 months.This hiatus from training ostensibly provides a buffer against parent-child power struggles that arise from premature demands for independent toileting*2, which in turn would prevent or attenuate the sorts of behavioral cycles (eg, chronic stool withholding and constipation*3) that tend to resist correction and block future progress.
*1 - Collect data on voids, time of the day or night, amount, fluid and food intake (what, how much, when).
*2- It is not only premature demands for toilet training that can generate an aversive history that will complicate training. Poor planning aside, even considering a good toiling plan that included information about the particular child and his/her learning history and preferences, the data collected, and so on, might need timely tweaks. In my practice the first implementation has to be supervised by the behaviour analyst because a lot of tweaking can be done right there, before they leave it to staff and parents until the next visit.
*3 - Be very vigilant about constipation. It can be immediately dangerous and even life threatening and it can cause a cycle of failure: child holds, it hurts, it hurts much more to have a bowel movement, child avoids bowel movements. Talk to your doctor about when to consider an emergency. I have worked with as little as 2 days without a bowel movement being recommended as visit to the emergency room because of a previous history.
  • What methods exist for toilet training?
A behavioral and a non-behavioral one, both described in the Pediatrics full article and reading it may sway you in the behavioural direction.
  • Is there evidence for the Applied Behavior Analysis method?
Yes, as the statement below will indicate.
The now widely popularized method of applied behavior analysis has been compared favorably with other methods and has been used to document the efficacy of the component approach more than any other method.( n14, n16-n20) However, all these versions use the same four basic protocols: increased fluid intake, regularly scheduled toilet times, positive reinforcement for correct elimination, and overcorrection for accidents. 
The source article (Pediatrics) of the quote above goes on to identify disadvantages of using overcorrection, for example. There is discussion in the field about the necessity of overcorrection to the success of the behavioural method of toilet training. My opinion is that it is not necessary to include overcorrection and I have not even been involved in many toilet trainings with this component. Some concerns I have are that every individual responds differently to the contingencies, thus the usual overcorrection might not at all have a decreasing effect. What should be involved in the toiling overcorrection is not set in stone and different people choose different things; clean mess, re-do what would have been the right chain, once, twice, five times? I will not go on and on about how this does not result in practicing the appropriate behaviours under the appropriate motivation, which is essential. It is also risky that in unsupervised environments it may bring more aversiveness than necessary, such as angry disapproving faces, punishing statements, or more. I do not accept this type of treatment.

Previously in the ABA Blog: Toilet Training Readiness