This is written in the spirit of “Thinking in public”

It is by no means an authoritative guide, but more of a snapshot of my (baby intermediate, 75% lead) current understanding of the idea. Feedback & contributions are welcome!

Lead projection in West Coast Swing is the technique of foreshadowing the upcoming movement (pattern) through positioning within the slot, adjusting the pitch, rotation, etc at the end of previous movement.

Lead Projection is also sometimes referred to as "pre-leading" or "slot dynamics".

Why

This leads to one pattern influencing the next, giving a consistent flow to the dance.
Reduce the amount of work/force required to lead any given pattern - as the follower is already partially prepared for the movement - only a very light lead is required.
Reduce cognitive load for both leader and followers by constraining the space of possible patterns.
Give follower more time to figure out appropriate styling based on upcoming movement. If the follower knows (roughly) what pattern is coming next, it is easier for them to plan musicality and variations that are compatible with the next pattern.
When follower does the projection - it allows them to request the (characteristics of) next pattern
- By picking their own position, the follower can put the partnership in new configurations that the leader might not have in their vocabulary, or encourage the leader to pick specific moves to match the music.
It also helps leaders to determine how ready a follower might be for a certain move. For example, over-rotating the follower preps them for rotational movement to follow. If when you're trying to over-rotate them they stay more square - that's a sign that you should probably try leading something more linear in the next pattern.

How

You create a projection by adjusting your position, pitch or rotation at the end of preceding pattern (~through last 2 counts of it).

Projecting Direction

People often talk about slot as "train tracks" - you can imagine leader stepping onto one of the rails or staying in the middle as a way to indicate the direction of next pattern to the follower.

If leader is in the middle of train tracks - blocking the way of the follower - that implies a blocking pattern is coming (e.g. sugar push or sugar tuck).

If the leader is off to a side - they are inviting the follower to pass them on the other side.

Example: leaders offsetting to their right ...

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