This article is a Stub. Needs some editing, additional ideas, resources or organization.
We've (The Crisses) seen switches take place with "tells" for some systems (we've known a lot of systems in-person). We're cataloging some of our own impressions, things we've seen, and the things we look for.
If you have the pleasure of watching a plural switch, you can really come to appreciate a wide variety of how body language and other unconscious mannerisms can express a person's individuality.
Most of the time, we aren't trained to be very observant of subtleties of personal expression. As a child with a DID father and a BPD mother, we had to learn to spot tells and switches of plural system members (or of identity-states in BPD) in order to switch our own fronts in our system and compensate for challenges in our home environment. This made us extraordinarily sensitive to noting posture, gait, micro-facial expressions, differences in vocal tones, etc. We could spot "who our father was" when they came home from work from halfway down a long New York City block — we knew right away whether it was going to be a good night, or we were already in trouble just for playing outside with our more lenient mother's permission.
If you want to train yourself to spot switches, become a people-watcher. Sit in a mall or other place with plenty of body-people, and do a study of what unconscious habits and mannerisms make external individuals different. Keep an eye out for self-expression, muscle use, posture, facial expressions, range of motion, gait (how they walk), speed of movement, etc. Compare how people who are together will express themselves differently, as well as people who are not together. Could you tell the individuals apart if they were only silhouettes? What if you swapped the mannerisms, activity level, range of motion between a child and an elderly person?
Make sure to tune in not to just individual changes — say the difference in gait between two teenagers — make sure you look for groupings or sets of differences. Example: if you are observing are 2 teenagers having a conversation — watch how they sit/posture, gesticulations, laughter, their smiles and range of facial expressions, vocal tone and range of word choices and placeholders. You should start to get a larger picture of how they're different and how they're alike. Maybe they both slouch into the cushions of a couch, but one is totally relaxed and just talking, while the other is animated, cursing, gesticulating wildly, and their knee is bouncing the whole time.
Once you learn how to adopt a perspective or paradigm lens of looking for these differences, it should become easier to spot the differences between the members of a plural or multiple system. It may seem to be very subtle. After all, it's the same body. However the external traits of the person utilizing their body can make for some fairly notable differences in these observable factors that would typically slide under the radar for most people.
With an estimated 1-3% of the general population being DID (before even considering other types of plurality), a plural switching is potentially so commonplace it could be mistaken for moods, modes, or role-based behaviors. Where some plurals think they're being flagrant, often singulars completely miss the tells and differences.
A fairly wide range of personal expression is considered normal in society and attributed not to different internal people, but to differences of emotional expression or energy level. This may frustrate plural system members seeking recognition, yet it also helps plurals mask and pass in our society.
The overwhelming majority of plurals are considered to be "covert" or passing as singular systems and it's only when there are drastic differences such as accent issues, language issues, or littles behaving overtly like children that we are generally considered overt or "flagrant" (this is derogatory) presentations.
Of course any of these changes can happen to a degree in singular folks, but they usually happen with a change in topics, roles, social situation, substance use, or over a long period of time. Examples are being alert after a cup of coffee and drowsy & inattentive after a heavy lunch, or someone who curses often who doesn't curse around their mother, or a pick up in pace and gesticulation when talking about something they're wildly passionate about.
Compare this issue with having a singletsona: a mask or persona that the system uses to appear singular. It helps them average out their tells and behaviors or modulate their voice so that their changes are within the range of what is considered normal for singular folk. It's very similar to an autistic mask: it's a defense mechanism to help the plural system avoid scrutiny or socially negative attention.
So for prudence's sake, don't use these ideas to "diagnose" people. This is a tool set to try to help people deal with those they already know to be plural or multiple. Don't assume seeing changes in people must mean they are plural — this isn't for diagnosis — this is to help partners and plurals to spot the switches (even their own switches!!) in a plural system. If a known-plural is calmly talking to you about something, then suddenly shifts position, leans forward, starts gesticulating, sitting on the edge of their seat ramrod straight, smiling and speaking in a high-pitched voice — maybe that's not just a change in topic or mood. Something else may be going on there.
As mentioned above, to get better at spotting these shifts, pay more attention to anyone and the wide range of variety in how people express themselves in real life: how differently people walk, talk, move, think, speak, act — and that all becomes possible in a one-body plural system. Once you start looking for these differences between people's self-expression in general, the easier it is to spot them when with someone with DID.
There are sometimes "Tells" or signs of when a system switches. These tells may go away over time as a group becomes more co-conscious, or may only happen when certain residents take front. Switching and dissociation are 2 different issues that often overlap or happen at the same time for systems with dissociative amnesia, however as their system becomes more co-conscious or experienced at switching, they will dissociate less when switching.
Any individual in a system will have their own range of behaviors and mannerisms and emotionality. When looking for signs of someone switching, don't just look for one change. Look for groupings of changes that are generally consistent.
Just because X leans forward and raises their voice does not mean a switch took place. There's usually going to be more than just a few subtle changes to indicate that someone has switched. There's no exact number of changes of the below observations that must be met. It's not a checklist with "points" etc. Once you know the types of indicators to look for, however, you may spot patterns and sets of different "tells" that indicate specific individuals are fronting. It's like playing a game of "Spot the differences" so you can tell who is out at the moment.
While each individual has their own range of emotions that they express per their own individuality, they also — much like singlets — have a typical manner and perhaps "set-point" in their emotionality that can vary from individual in the system to individual. Let's say their "natural" emotional mood or temperament. Kind of like a particular album of a particular music group — there's a range, style and composition of emotional quality or musical tone about the recordings in question. Put on a different album, even by the same band, and it's generally obvious something is different. Thus switching from a band's first classic rock album to their last recordings you definitely know something is different.
A simple emotional shift with cause is not a sufficient tell. When the "set" or grouping and "style" of emotional expression changes drastically, it's likely to be another person.
That grumpy person may not be "X when they are upset" — it could be "C on a normal day". Thinking that individuals in a system are always stuck at one particular emotion can lead to some strange assumptions about reasonable emotional shifts. "Did you switch?" "No; my hamster died — I'm just upset."
Therapists, TV and movies often get this wrong and conflate an individual's mood changes with a switch to an "emotional part." Of course it MAY be true, but it also isn't usually true. Thus thinking X switched because they seem upset is a mistake, where asking C what's wrong might make C more upset than usual because nothing was wrong; that's just how they are.
In terms of emotionality, what might be a better "tell" is the quality of a person's expression of different emotions. A normally happy-go-lucky person can be disappointed — but that disappointment probably wouldn't make them so bitter that they're vindictive. It doesn't change their ethical compass to something wildly inappropriate to their individual nature. Just like any other person in their own body who would normally be happy-go-lucky might be disappointed but not vindictive.
You might see that if A is disappointed about something, their protector D may switch to front (as A goes deep inside to nurse their disappointment) and D might seem angry or agitated. This may lead to a conclusion that when the group "gets disappointed" that their protector expresses the group's disappointment as anger.
What's probably going on is that D has fronted to protect A or to allow A the space to internally process their vulnerable or uncomfortable emotion. Basically A gave themselves a time out. D may not be angry at all; they just normally act and behave and have tells that appear angry to you. Unless, in this case, you are the source of the disappointment. In which case, yeah D might be angry at you because whatever happened hurt someone they protect and care for, and they're not too happy with you at the moment. In all likelihood, they are going to be focused on making sure that the situation gets handled so that A doesn't feel vulnerable or upset any more — like any good friend or mediator.