Instinctual variant stacking describes an individual's preference for the three Enneagram instincts: self-preservation (sp), sexual (sx), and social (so).
Although each person uses all three instincts, an individual will have a 1st, 2nd, and 3rd preference. Unlike the instinctual subtype approach, the instinctual variant stacking approach can be used with or without reference to Enneagram type.
The instinctual variant stacking is indicated by the 1st instinct followed by the 2nd instinct with a slash separating the two (e.g., sp/sx for self-preservation 1st and sexual 2nd).
The 3rd or last instinct is omitted and implied by its omission (e.g., sp/sx omits the last instinct of social).
Here's a list of the six possible variant stackings.
Two people can be compared by variant stacking independent of their Enneagram types.
For example, two people can have the same stacking of "sp/sx" yet different Enneagram types. There will be similarities between them based solely on having the same "sp/sx" stacking.
This is quite different from the instinctual subtype approach. Instinctual subtype is used only to determine a variation or subtype of a type. It's not used without reference to Enneagram type.
Although variant stacking is independent of type, it can also be used with type.
As an example, "sp/sx" is only looking at the preferential order of instinct. The shorthand "sp/sx 1" adds in type 1 for consideration as well. You then might compare someone who is "sp/sx 1" with someone "sp/sx 2" and note they have the same instinctual stacking but different Enneagram types. You also might compare someone who is "sp/sx 1" with someone "so/sp 1" and note they are the same basic type but have a different instinctual stacking.
There's often a preoccupation with and desire to move toward the 1st instinct. This doesn't mean the person will be adept at using or satisfying that instinct. It means there's a pull in that direction.
Someone sp-first, for example, may have a strong focus on satisfying self-concerns and be drawn toward those more than the concerns of the other instincts. In other words, for sp-first the sx and so instincts will take a back seat to the sp instinct when it becomes activated.
For sx-first, the object of interest becomes primary when activated. With so-first, participation in and expectations from the social structure become the pull.
The 2nd instinct is a fallback when the 1st instinct isn't active. It's a home base where a person is comfortable being. It becomes a resource for the pursuit or satisfaction of the 1st instinct when the 1st instinct kicks in.
Taking sp/so as an example, participation in the social structure would feel comfortable and familiar but the social would also be used to satisfy self-preservation concerns.
It's as if the individual is living in the 2nd instinct with an eye on pursuing and satisfying the 1st instinct.
For various reasons, the 3rd instinct is often not paid attention to, sometimes to the point of the individual being blind to it. While the first two instincts are of more importance to the individual, the 3rd instinct is undervalued and underused. Because of this the 3rd instinct is often underdeveloped as well.
With sp/so, as an example, the 3rd instinct is sx. The primary focus is on satisfying self-preservation concerns using the social instinct to facilitate this focus. With sp concerns being aided by the so instinct, the sx instinct becomes of little value. As a result, the sx instinct goes underutilized and remains underdeveloped because it is mostly forgotten, ignored, or even avoided.
A person can become blind to their 3rd or last instinct because often they just don't notice it and what it's telling them.
Confusion can arise when trying to determine whether an instinct is 1st or 3rd. Both can be underdeveloped because an individual may not have much experience with either; the 1st instinct because it's missing and being sought and the 3rd instinct because it's undervalued and ignored. The difference is not whether a person is good at using the instinct, it's whether they are drawn to it (1st instinct) or apathetic/blind to it (3rd instinct).
An individual may sometimes give up on pursuing their 1st instinct for a time in frustration, only to remain obsessed with it at some level. With the 3rd instinct they might not simply be apathetic but also avoidant of it or bothered when pushed to deal with it.
While the 1st instinct is where a person feels most fulfilled when they successfully satisfy the instinct, the 2nd is where a person often feels most comfortable or familiar because they spend so much time with this instinct. Also, if the 1st instinct is not satisfied, there's a nagging desire to pursue it. There's not the same need to satisfy the 2nd instinct because it seems much more available.
The 2nd instinct is often important to the pursuit of the 1st instinct and can be more effortless and comfortable to use. Whereas the 3rd instinct is generally not seen as important, often requiring extra effort to pay attention to it and use it.
Although instinctual variant stacking is independent of Enneagram type, your Enneagram type will operate in accordance with your instinctual preference.
For example, an sp-first type 1 will direct criticism more toward the self. With sx-first it will be more about the other or relationships and so-first will be more about social appropriateness and responsibility. This is where the instinctual subtype approach overlaps somewhat.
You can take the instinctual variant stacking test available on this website to help you determine your instinctual preference.
If you know your Enneagram type then you can take the instictual subtype comparison test also available on this website.