Example of a Secondary Action - the primary action is the swinging of the pendulum, the secondary action is the movement of the "tail":
An important rule about secondary action is that it should not dominate or detract attention away from the primary action. If this is the case, the secondary action is most likely wrong for that particular scene, or staged incorrectly.
There are dangers involved with using facial expression as a secondary action, in that these subtle expressions may not be noticed by the viewer when combined with a dramatic movement. It is often considered better to include facial movement at the beginning or end of a greater movement, rather than during. In some scenes the facial expression may be the primary action, in which case the secondary actions must be carefully planned around it so they do not detract from it. In other scenes, the facial expression may be used as a secondary action, in which case it should be staged so that it's obvious and visible to the viewer, yet isn't dominating the primary action.
Here are some examples I found of where I have tried to use secondary action in animations I have made.
In the one below I tried to use subtle extra movements to emphasize the effect of the primary movement. For example when the character is pulling his leg back to kick I made him also pull his arms back to emphasize the turn of his whole body and the effort he is putting into it. I also tried to include some expressions, but some of them are poorly staged in this animation. I thought this was still appropriate to show though as it's good to see examples of both good and bad uses of the principles.
I think that the times when the expressions come before or after an action (for example his rolling eyes after he has been swung violently to the side, or his look of confusion before he falls) work quite well, but other times when the expressions come at the same time as the actions (for example the look of fear when he cowers from the hand, and the look of shock as he is falling) the expressions are completely lost and cannot be seen.
Open Brief from Rebecca Hahner on Vimeo.
I've been looking at delayed secondary action in preparation for our presentation;
Delayed secondary action is used in order to create more life and movement within an action or hold, when moving a character from one action to the next, if one part arrives later (e.g the tail of a squirrel) then it allows the action to con
tinue on, making the sequence more believable.
Below is an image that I found showing the movement of a squirrel, here the secondary action is the movement of the tail as the body jumps, and the delayed secondary action is the movement of the tale once the squirrel has stopped moving it's body.
I used this image as a guide and created a short animated sequence showing the delayed secondary action:
lack of secondary action: