System Regression

System regression is an unconscious response to new trauma that causes the temporary, or long-term loss of integral system functions and awareness of their plurality. Much like regression outside of the scope of plurality, when a system experiences regression they will revert back to an earlier stage of their development in an attempt to feel psychologically safe. This may cause partial, or full reversion of system functions.
This phenomena is similar to the developmental regression typically observed in, but not exclusive to, autistic children. In that it describes the process of a person who had previously exhibited normal development progressively lose the key 'milestones' they have acquired.
Not to be confused with system-wide age regression, where the entire system is age-regressed.
=== Partial Regression ===
Partial regression can be described as the reversion of only a few system skills while the system as a whole retains awareness of their plurality. For example, a system that was once able to communicate with relative ease has unconsciously lost their ability to communicate with their headmates, but still be able to see within their headspace in order to affirm that fellow system members are still there.
Alternatively, it may be described as the indiscriminate, yet incomplete reversion of all system functions. A regressed system may experience difficulty with communication, visualisation, memory-sharing, and switching, but not to the degree that it makes them unaware of their plurality.
Partially regressed systems may still experience large-scale dormancy.
=== Total Regression ===
Total regression can be described as the full reversion of all system functions (communication, visualisation, memory-sharing, switching, etc) and member count. When a complete regression occurs the system will collapse and experience a mass dormancy, reverting the collective back to a functionally singlet state; reinstating previously broken down amnesic barriers, cutting off access to headspace, and leaving an intentionally unaware host behind to continue leading the collective’s life.
This is done when new trauma arises and forces the system into hiding for the sake of safety. However, unlike a system collapse where a system experiences a large amount of headmates going dormant or hiding, a regressed system will have to gradually rediscover their multiplicity once it’s safe to do so.
Unlike partial regression, where the effects can be temporary or long-term, complete regression of a system is typically a long-term change due to the increase in dissociative amnesia, and amnesic barriers to protect the host's identity and quarantine previously learned traumatic memories. Because of this it may take months or years into the system's rediscovery to learn they ever regressed in the first place.
== Related Terms ==
Partial regression may create long-term post-regression, communication barriers by inhibiting communication throughout the system. Whereas subsidance can have a similar impact on the headspace as regression, i.e. making areas of, or the entire headspace inaccessible, but for different reasons.
System collapse is not an experience attributed to regression and can occur without the reversion of system functions and learned skills. However, regressed systems may experience a collapse in headcount.