learning the ropes

things I made at ITP and after: sketches, prototypes, and other documentation

Friday, January 18, 2008

User Testing

Yesterday, several people looked at my rope and pulley instrument / interface. Generally speaking, they all liked what they saw and found the interface to be intuitive. I didn’t have to really explain what to do with it — they “got it” almost immediately.

The Test Setup
- rope & pulley system connected via Arduino to computer running Max patch
- computer connected via MIDI interface to Roland M-DC-1 dance module

When my right side faces the computer, pulling the rope towards my body triggers a note on the MIDI synthesizer. Pulling the rope with increasing speed increases the volume of the note as well as a sound modulating parameter. Decreasing the pulley’s speed decreases the volume and modulation parameter. When the pulley stops rotating, the system turns off the note on the synthesizer.

I also demonstrated the original performance patch which plays Jimi Hendrix’s “Red House” when the rope is pulled.

- It was difficult for me to come up with questions on the spot to ask other than, “how did it feel?”, “was it intuitive?”, etc.

- I was hoping to observe something that would bring me an idea for the next direction, but I’m not sure if I saw something.

- I found myself explaining and demonstrating the system to generate interest in the idea even though the system was only playing a single note.
- The system needs a bit more refinement in order to demonstrate it quickly. I sometimes get flustered when I switch between modes because it doesn’t work immediately. I either need to write down the steps for setting it up or fix the Max patch so it does a few more of the setup functions automatically.

- When Amit was teaching us about user testing last year, he focused on picking a particular task. What was the task I wanted tested? It was hard to get specific answers because I wasn’t asking specific questions.

- The responsiveness of the system is an important feature. Right now it feels good.

- All testers found that synthesizer version of the system really needed something to happen when the string was pulled back in the direction of the sensing wheel. It wasn’t clear what that something should be, though. Shinyoung suggested some sort of record scratching sound. Rui understood the technical problem I was having with mapping volume / modulation with a positive and negative motion source. But he agreed that it felt strange that nothing happened in the “negative” direction. For this reason, he found that he liked the interaction with the computer-based sample playback (“Red House”) better. The sample playback corresponded directly to the motion he was making with the rope. As he pulled the rope towards his body, the sample played “forward”, slowing down and speeding up as he pulled with varying speeds. When he pulled the rope in the opposite direction, the sample responded in kind.

- One of the testers was very much interested in the body motion available as a result of this system. Being a “non-musical person”, she was interested in how someone moves when playing the instrument. She wanted to see the installation of this instrument afford a nice set of gestures / body movements for the user. To observe this sort of behavior, I think I may need to build another unit that can easily be mounted horizontally, vertically (or on any angle, for that matter).

- Another tester enjoyed the materials the system was made out of. He felt like he could be rough and expressive with it because it was made out of discarded materials. Because the interface was not “precious,” he felt that he could play hard. He mentioned that he wouldn’t feel bad breaking the string or some other part of the mechanism because he had the sense that things would be easy to fix. If I can get the knot right, this would probably be the case. The only things I really worry about in the system as it is (made out of cardboard), is a kid trying to hang off of the rope. What I’ve observed several times is that people playing with an interface for the first time want to play ROUGH as the developer looks on in horror.

- I want the ability to change pitches on the instrument — but not with the pulley. I want some sort of system on the floor that allows discrete pitch selection. One of the testers agreed with this.

- There may be something important about the fact that you can hide behind this instrument (like a guitar, piano, or even a laptop)

- I am hesitant to provide speed control over the sample playback unless it has some very natural smoothing that doesn’t allow it to get too much out of control. These could be done as a series of short user feedback experiments. The other trick in allowing speed control is that stopping the rope must instantly stop the sound. This is one of the affordances of the current system. This could change if I add more mass to the pulley, however. A metal pulley will definitely want to keep spinning unless the rope is heavy enough (and has enough friction) to stop it.

- It was suggested that I ask other people (non sound people) should try it out and see if they get the mapping

- Jamie suggested trying a collaboration with motion theater people (like Judson Church) to establish a type of choreography.

posted by Michael at 11:43 am  

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