Ever sparred with someone really good and felt like you were at your best, then right after sparred with someone less experienced and felt like you got as sloppy as they were?
Mimicry is one of the brain's most powerful tools for both learning and fitting in (an important tool for survival). Jared Diamond in Guns, Germs, and Steel, speculates that the human penchant for mimicry helped migratory peoples adapt more quickly to local practices required for survival. Imagine coming over the mountains from an area rich in tree fruits to find yourself in an environment where everyone ate root vegetables. You'd do well to start copying those around you and dig in the dirt than continue to try to find your food in trees.
Fitting into a social group can also be a requisite skill for survival. Humans have long tried to identify same and "other" amongst those around them. It is important to be able to quickly align yourself with a group in order to gain its benefits (logistical and societal) and avoid the punishments of being part of the out-group.
Interestingly enough, these same behaviours are at work in your martial training. For many, no matter who their sparring partner is, these automatic systems kick in and you begin to mimic and match your partner, even if what they're doing is less than ideal. In one situation, against the very good sparring partner, mimicry is an advantage. It will help you keep up with them a little more, and perhaps some of those copied skills will stick. Yet, I've seen many excellent fighters lose their edge and fight far below their level when dealing with someone who is relatively new, sloppy, and poorly structured.
So how do you avoid mimicry when it doesn't serve you?
Set Strategic Goals
Being aware and responsive to your opponent is an important part of defeating them. However, if you go in as a blank slate, without any strategic goals, it's easy to have your opponent dictate not just the rhythm of the fight but the structure and form of how you both move. Decide on how you intend to approach someone strategically, and set some goals around that, before you cross swords.
For example, you might choose to attempt to exploit a particular target. You might seek to control their sword in a particular way. You might also aim for a particular tempo (moment) to strike in.
By giving yourself a specific objective you can focus on the implementation of that objective and using your own existing skillset, rather than ending up simply dancing with and mirroring your opponent. Anytime you find yourself in a space of mimicry, zero in on your objective and let your conditioned responses get activated as you try to solve the problems that arise.
Set Movement Goals
Different than strategic goals, you can give yourself some postural, movement, or position goals to aim toward. This could include setting a focus on a particular posture or guard, carrying your weight in a particular way or focusing on alignment, or making a particular position your end goal.
By focusing on staying deep in the legs, making small sword movements, or getting to a particular guard while still in control, you can again break through a desire to copy and instead put yourself in the position of role model. This approach is particularly useful in practice sparring, where you can set aside "winning" to focus on improvement.
Define Your Training Environment
If you find a particular partner often leads you into sloppy practice, then create a structure to your practice with them that restricts what is possible. Use a sparring game that takes you away from the sloppy areas or specifically rewards precision and punishes the common errors you make together. Taking away traditional winning objectives will help with focus and remove some of the negatives of mimicry.
Take a look at this article for some ideas on sparring games for more ideas.
Mimicry can be a benevolent force. I try to get as much time in as I can crossing swords with people who have qualities I want in my own swordplay. Not only do they challenge me directly, I can also copy the way they move to help me understand and adopt it for myself.
When I'm preparing for a competition I try to start my warm-up sparring by spending time with high quality, precise, and challenging opponents. I use this to set my fundamentals in the right place. Then I seek out someone who is less experienced and fence them with objectives in mind, to help me put myself in the driver seat for setting the tone of fights, rather than marching to anyone else's drum.
I'm interested to hear how others have both dealt with and leveraged their own penchant for mimicry.