Practicing Repeatable Physical Skills – With an amazing example

I know that there are some schools that are using or experimenting with Dartfish to improve the teaching of novice interpreters for American Sign Language. This makes sense because accurate signing is a precise physical skill that requires rigorous training and practice. Lasca Thiede is a friend of mine and a very experienced interpreter for American Sign Language. She kindly agreed to help me experiment with two Dartfish features that intrigued me as possibly relevant to this type of repeatable skills and activities.

Skill Consistency Comparison

The blending feature that I used with baking machinery in earlier posts can be very revealing if it is applied to any visible action that is frequently repeated … including some human skills. To try it out, I made a video recording from a frontal view of Lasca repeatedly signing a 55 second excerpt from a speech by John Kennedy (the “we are going to the moon” speech). Over the course of 15 minutes or so, I asked her to do it 3 times.


Then, as the diagram shows, I took the videos of two signing segments and overlaid them with a Dartfish blend. The resulting blended video is, to my untrained eye, quite remarkable. There are many points in the video where her actions in the two separate sessions, taken about 2 minutes apart, line up and sync almost perfectly. Since facial expression is a key aspect of ASL, there are even points where the two overlaid video clips show her face in perfect focus.

Think about it. When Lasca signed a point in the speech a second time, her face position, expression and timing were exactly the same as in the previous clip. Exactly the same! To the point that her face appears to be in perfect focus because the two different video clips were in perfect position, time and expression alignment at the corresponding points in the two different sessions.

I am not by any means an expert on ASL or its professional performance, but I am amazed at Lasca’s consistency. Of course, she is very modest and points out that she has 25 years of practice … but I’m still impressed.

Video Time Machine

Dartfish can take live video input, buffer it in memory, then replay it after a specified time delay. Think of it as a video time machine. Its origins in sports are pretty clear. With this feature,. a baseball batter can take a cut, stop and look at a monitor, see the video replay of stroke that was just made, then turn back and try again. There is no need to press start or stop buttons or even to shift position or take the hands off the bat. Just take a cut, watch the replay … rinse and repeat. The videos can be recorded … or not … as desired.

The ability to perform actions repeatedly and stop and watch their performance after each attempt … nearly or totally hands free … is a very cool feature. The application in something like ASL or dance or other performance skills seems obvious. A learner can practice and then see a video of their effort immediately from another angle without having to leave their position or stance. Even better, this could be set up as a practice station and no one other than the learner would need to be present. It could be made anonymous or recorded and shared with a “coach”.

It’s a bit harder to think of applications in general industry, but there are repetitive skills that pop up in various situations, as the following collage from YouTube videos shows.

Hence, there may be situations where this sort of capability might be a useful addition to a training department or service. I am hoping that readers can think of places where it might be worth doing an experiment to find out:

  • Hand skills where a repeatable action can be perfected (the window cleaner’s two handed cleaning method in the previous video might be a possible fit).
  • Therapeutic skills such as massage technique
  • Salespersons practicing their “elevator pitch”
  • others?

Can you help?

I’m not an employee, investor or reseller for Dartfish, but they are kindly letting me play with it to explore any non-sports uses I can cook up. I am willing to play with videos sent to me by others as long as they don’t hold me to a deliverable timeline and they give me permission to post useful pieces on the blog.

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