Those with autism spectrum disorder often take what they hear said literally. This can improve with age and experience as they get used to different saying and what those saying mean, but usually even as an adult they struggle with conceptual language. So for me personally, I know I still don't understand what someone means when they say that something they have eaten is sharp, especially when they seem to say it after eating say a lemon which is soft and doesn't have any sharp edges. I could understand if they were eating an overcooked roast potato, but it doesn't make sense to use descriptions like that when eating soft food. Or descriptions like saying what they are eating is heavy, again, I've weighed food and can't seem to find it any heavier than anything else. I don't understand what this explanation is supposed to mean. I have tried Googling it, and had my wife try to explain these things, but I still can't grasp what they mean. I can understand someone eating something hot and saying it is hot, or eating something spicy and because it can make it feel like your mouth is burning, I can understand this being described as hot, or eating ice-cream and describing it as cold, or soft, but there are lots of descriptions which totally elude me.
I have heard people say that you can't use metaphors with people with autism, and I don't think this is the case, I think it depends on what understanding the individual has, but metaphors are a great way to lay down patterns because patterns are how the brain works. So even if someone with autism doesn't consciously understand the meaning behind a metaphor, if there is a context set around the metaphor - for example "you are here to quit smoking, and I'm here to help you quit smoking" then a metaphor about moving from a congested city and out into the clear fresh air of the country may not consciously make sense to the person, but when you tell one metaphor after another all with the same underlying pattern they will start to non-consciously pick up on this pattern, and if this went on long enough they will probably pick up on the pattern consciously. This is the same for example with if they love reading a specific type of novel - like crime thriller novels. Once they have read enough novels they will be able to tell you the structure (underlying pattern) of the novel - that there is perhaps a murder scene at the beginning, then an investigation, then interviewing the killer, but discounting them, and then thinking it is someone else, then finding some key information that makes them realise it was the person they thought it was initially, then a scene capturing that person, then ending with a positive rounding up scene. The author may have this same structure to all of their novels, so it become a familiar pattern and the story over the top of this pattern can vary widely, but the pattern will be there.
Recognising patterns is something those with autism are often very good at. So I am good at noticing patterns in therapy sessions with clients. I don't get bogged down in the content of the problem, I can see the structure behind the problem which is maintaining the problem, and when you work with many hundreds of clients you recognise that there are only a small number of patterns to problems clients present with, a bit like there being only a small number of structures to well written stories, but there are millions of different stories.
Many with autism may struggle with finding words, they may make up words or sounds to replace the actual word, and can get frustrated when others don't understand them, and the more frustrated they get the harder it is to find the correct words. Often words can be things others would think you should know, and can get annoyed that you aren't finding the right word. So I could suddenly not be able to 'find' the word 'cup' when I'm trying to talk about getting a cup from a cupboard. I will pause and think and try really hard to recall what the name of it is, and yet the word could completely elude me, so I will make a word up, or what frequently happens I describe things by their function, so I may say 'could you get the hot drink container out of the cupboard', and then hope the person understands what I'm talking about. Or I may say can they get the fibble out of the cupboard, or some other random word or grunt, often while frustratedly pointing. This can lead to talking slowly so that you have time to 'find' the words in your mind first, and to be saying what you are about to say out loud in your mind slightly ahead of what you then say out loud.
I also find that I often structure sentences differently to others, and will get elements in different orders. I also rarely use people's names in what I'm saying. Getting stressed or anxious makes this more pronounced. Many with autism use simple sentences, and are better at mimicking and reciting others sentences, than coming up with their own.
From a communication perspective I find myself mimicking sounds and words people say. Often if it is words people say it is the last couple of words in a sentence which seems to have a rhythm to it, and this last word or two stick in my mind and play over and over, and I will often repeat it, or I will end patterns, so if it seems someone hasn't completed a pattern - whether it is something they are saying, or a part of a song I'm hearing where I think it has ended before the pattern is complete, or a tapping or bird sound etc., I will feel compelled to complete the pattern. I copy mobile phone ringtones, bird songs, words people say, accents people have, and all sorts of other things, and sometimes this can get me in trouble, and I know many others with autism do the same. If someone says something and I instinctively copy their accent they can take offence to this even though no offence was intended, if I copy someone's mobile phone, or telephone ringtone I've had people say 'are you taking the piss?' when until they brought my attention to it I didn't realise I had done anything. Or I spontaneously say or do something that is in my head - so I could suddenly get the urge to whistle something because the pattern started in my head and now is coming out of my mouth, or a pattern of saying something is going over and over in my mind, and I feel compelled to complete this for real and will suddenly say out loud what I was saying in my head. Or I will suddenly want to tap or touch something, or to click my fingers, or crumple something up, or do some other behaviour - sometimes something which would be seen as inappropriate, like touching someone's clothes, or touching something that belongs to someone else, or crushing something that belongs to someone else - like cigarette packets, or to organise something of someone else - like wanting to organise the food on their plate, or correct how they have their cutlery, or move their glass to where I think it should be. Some of these things aren't socially acceptable behaviours, and as I have grown up I get greater self control and do what I can to focus on other things to avoid doing things which could be seen as inappropriate and could result in someone getting angry with me.
So a large part of communication as someone with autism is copying and mimicking, but not in a rapport way where you are copying because you are in rapport and you have greater understanding of this, but copying because of the pattern you have noticed, and you like that pattern. This also goes for answers to questions. I think many people with autism give answers they have learnt they are supposed to give without necessarily understanding the answer, and perhaps understanding the actions behind the answer. So someone could say they are sorry and that they won't do something again because they are sorry, and they know this is what they are supposed to say, but they don't change their behaviour because they were just saying what they were supposed to say, they didn't internalise and understand that part of the message is to do what you are saying, so you should aim to not do that thing again.
I know for example that I can say to someone 'that sounds like it was a really difficult situation' and the person will feel empathised with, but I am just saying words as far as I'm concerned. To the person they obviously found the situation difficult because they have just described how it was a problem for them, and so anyone describing something as a problem they have been through probably found it difficult. But I don't feel anything for the person, I don't have any empathy, I don't usually understand why the situation was a problem for them, and why they decided to feel bad about the problem, I just know they like hearing that it sounds like it was a really difficult situation, and I know that I can say that as a way of opening up conversation and moving the conversation in a more positive direction. This has only been learned from studying psychotherapy and becoming a therapist. Without that training I wouldn't do this.
Another challenge with autism is understanding communication. This is especially difficult in the world of work where you get given a long monologue by the manager about what you need to do and by the time they have finished talking you have forgotten nearly all of what they said. Information needs to be given in small chunks, and in bullet pointed lists. It is very difficult to hold all of that information in mind. Even working for myself, I find that I forget things and mis-remember things too often. For example I can have a talk coming up. I will have it written in my diary and will check my diary daily and remember the talk, and yet on the day I will still have remembered the wrong time or details, or sometimes the wrong day - even though I've tried to keep track of the talk details, so I have to keep track very closely to my diary and to lists, and keep referring back to the lists.
I prefer someone to give me one task at a time, once I've done that task then tell me the next task, rather than say 'here are three things to do by the end of the day' because I won't remember them, and even writing some notes, I will most likely forget further details, and any distractions can make me totally forget what I was supposed to be doing and where I was at with it.
And linked with social communication, it is easy to communicate one-way, so talking at people is easier than talking with people, being asked questions about an interest are usually easy to answer, but if the conversation becomes a chat then it gets difficult, so if I suddenly have to try to answer questions about how I'm feeling, what I think of things, how my day has been, etc., I won't know how to answer, and when I do answer - usually with 'ok' or 'going home' or other short, blunt answer, I don't have the skills or knowledge to continue the conversation. I, and many others with autism struggle with the reciprocal element of communication. So I am very unlikely to engage in how your day was, what you are up to later, what you think of things, what you are interested in. The communication focus will be on talking about what I am interested in, and what I want to be talking about.
It is also common for those with autism spectrum disorder to talk with unusual rhythm, or monotonously. I have to try really hard not to talk monotonously, it takes a lot of effort. When I hold therapy sessions I have learned to use my voice, and to use different tones of speech to communicate additional ideas and meaning to clients, but in ordinary conversations when I'm not focusing heavily on how I am speaking I find I can go into monotonous monologues where I am just talking at the other person unaware of whether they are interested or not. It is also common for those with autism spectrum disorder to have volume control issues. My wife will frequently tell me that I am shouting when I think I am talking at a normal quiet volume. I don't know why I can't notice that I am talking too loudly, but it annoys me when it is pointed out to me, because to me I was talking normally, and I get annoyed with myself for not talking correctly and not noticing this. I can also find it difficult to hear people at times, yet I think I generally have good hearing - I can often hear very quiet sounds, but seem to struggle more to hear, or at least understand speech. I often need televisions to be turned up louder to hear speech, compared to other sounds. Yet it is as if my senses are attended to noticing things I'm interested in, so when someone says something I'm interested in, I can notice this from across the other side of a room.