PhET Wave on a String Sim - Design Brainstorming
Background Information
Sim name: Wave on a String
Link: http://phet.colorado.edu/en/simulation/wave-on-a-string
Goal: Analyze the sim and brainstorm design issues (including accessibility and inclusion design issues) and possible solutions. This sim is not currently a sim being worked on as part of any grants - it's purely chosen as an example for a design exercise.
In attendance:
- Dana Ayotte
- Simon Bates
- Julia Foster
- Jesse Greenburg
- Alan Harnum
- Jonathan Hung
- Justin Obara
- Tim Park
- Sepideh Shahi
- Taliesin Smith
- Godfrey Wong
This document is a compilation of notes resulting from a meeting that occurred on July 21, 2016
Description of Sim:
Link to the sim: http://phet.colorado.edu/en/simulation/wave-on-a-string
On first load, the screen shows a string of beads attached to a wrench on the left side and attached / anchored to a clamp on the right side.
The wrench can be moved up and down with the mouse which causes a wave to travel across the string to the opposite end. The wave will rebound back.
Other controls on the sim modify the behaviour of the wave - “damping” and “tension”.
You can change the right anchoring to be “fixed”, “loose” and “no end”
You can also change the wrench control scheme from “manual”, oscillate, and pulse.
Some Challenges
Wrench control
Range - controls amplitude
Speed of movement - controls frequency / period of waves
Perception of string movement
State of the sim as a result of user actions
Wrench control challenge
The wrench controls two variables:
Amplitude
Frequency
What would this look like as native HTML controls for keyboard and screen reader access?
Amplitude could be a range slider and the speed of which the slider is moved controls the frequency.
Raises concerns for motor control
Could add an accelerator key of some sort which speeds up movement on the slider.
Inequality in experiences: Even if you use a slider or an accelerator key, the end user experience is far from the visceral experience that someone using a mouse has.
Could also consider having the pointer directly manipulate the wrench without having to click / depress buttons.
This would imply having the user switch into a special mode where the mouse / tracker acts as a wrench (i.e. shaking it would shake the wrench).
But the user would get into states where their mouse is controlling the wrench and not the actual cursor on the screen which could be very confusing.
It’s also possible to use the GPII Nexus to have another device control the wrench (a proof-of-concept was made on July 22nd using the tilt sensors on an iPad Mini to control the wrench).
Some users can not physically use a mouse or hold another device. How would control be done in this case?
Head tracker was mentioned but this could interfere with viewing and focussing on the wave
Perception of String Movement
Initial thought - map the wave created by the string directly to sound as a way of sonifying the data. But there are some issues:
How would you sonify the situation where the wave bounces back from the end point?
It’s possible to have a complicated scenario where the user reduces the tension and damping to 0, and create multiple waves. The waves are constantly colliding and passing through each other - what would this even sound like?
The sound of the waves still have to sound nice (even when multiple waves collide)
What would the sound differences be for fixed, loose, and open ended?
Using volume, pitch to represent amplitude and repetition to represent frequency was suggested
Is it useful to sonify a single fixed point on the string?
How can haptics be used?
Something like a braille device where you can feel the waves.
What are the most necessary pieces of information that need to be perceived? (what is the main objective of the physics sim? Understanding concepts or completing calculations?)