Generalisation means what it sounds like it might – being able to make a general rule about some things or acts which are specific.
Most of us know how turn on lights, fasten jackets, and open doors even though these are all tasks we can complete in a variety of ways. We might turn on a light by flipping a switch, pushing a button, or pulling a string. We can fasten our jackets with zippers, buttons, clasps, or Velcro. When we learned to do these things, we learned to manipulate a variety of “materials” to achieve the same result. We also learned to manipulate these materials in different settings. For example, opening the front door of your own home is very similar to opening the front door of someone else’s home, a car door, or the door of the nearest fast food restaurant.
A dad of a young girl with ASD recounts:
Emma, like many children diagnosed with autism, has a difficult time applying something she's learned in different situations and settings. For example when she was much younger, I tried to teach her what a t-shirt looked like by holding up an actual t-shirt, one of hers with a pink heart on it. She was able to remember what that particular t-shirt looked like and called it a "t-shirt". If I then took out a different t-shirt, one of mine, or a different t-shirt from her drawer, she was not necessarily able to understand that this too was called a "t-shirt".
Autistic children have excellent memories and often rote learn information, but they usually only apply their learning to that specific time, picture, object or with that particular person. For example – if I use a picture or an actual piece of fruit to teach recognition of an ‘apple’, Ngahuia is likely to believe that it just means that one apple or picture. Unless I include generalisation of apples - different types, objects and pictures as part of the learning, that is what might happen.
You might observe a typical child in a particular situations – if Mum says – “say ‘thanks for coming’” to Oscar when he comes to play and another friend Jimmy has also come to play, most children are able to think "hi” was appropriate in this situation, so it's probably appropriate in the next, similar situations. In other words, they are able to identify the significant similarities in two substantially different situations.
Social examples are more challenging than teaching situations as there are often a lot of variables of situation, people, cues, people and other factors. Sam has been taught how he has to line up to go to assembly, but won’t necessarily know how to do the same for a class trip to the pool or the gym.
There are several reasons for generalisation being difficult. Autistic individuals like to categorise rather than generalise and they also are not strongly motivated to watch and imitate others. This makes also makes it hard to intuitively grasp differences in situations. How far should you stand from another person? How loudly should you talk? There are no absolute rules about these things: neurotypicals "just know" because we are constantly surveying and imitating the social cues of others.
Generalisation can get especially tricky when children taught skills in a separate, one-on-one setting and then expected to use those skills in a social situation. In a one-on-one situation, the child may be able to throw a ball back and forth - but he may not understand that he is learning this skill in order to use it on the playground or during fitness. Obviously the next step is to teach some turn taking skills and teach the skill with peers during fitness. However, it’s likely to be necessary to explain ball tossing with peers in the classroom is NOT acceptable, while ball tossing in the backyard with your brother is a great idea. Each of these different situations is both different from and similar to the playground -- and it can be very difficult for the child with autism to determine which details are important enough to change the rules.
Generalisation needs to be part of the planning with every goal. A wise person once said that a skill is not learned unless it can be used in a variety of settings, with a variety of people. It is also important that new skills are generalised between home and school. For most autistic children, then, the issue isn't "can s/he learn to do X," but "how can s’he learn in the right situations, in the right way, at the right time, with the right people."
Too often, I hear parents or teachers saying “Oh, but they can do XYZ at home” as if there is something the other setting is doing incorrectly. If they can't do it in both settings, they can’t do it and it’s our job to make sure they learn!