Experiments
Setting up object interaction experiments in RB15 - general
- Arrive 5 minutes before participant is scheduled in order to turn on the equipment, sort out your paperwork, and make sure your stimuli are where you need them to be. The golden rule is that subjects must never see you lifting or moving about any of the stimuli at any point before or during the experiment.
- Switch on plug at the wall behind the monitor.
- Turn on testing laptop using the button beside the word 'Toshiba' on the docking station, and log in.
- When the lap top has booted up, double click the matlab icon labelled 'Forcesensors'
- In the window which pops up, click on the ‘run’ icon (green triangle/arrow, near the top of the screen. This will bring up a window with boxes to input stuff.
- Click on the ‘folder’ box, and navigate to where you want to save your data. This should be in a folder with the participant number (e.g., P1), inside a folder with your name.
- In the ‘file name prefix’ box, input the name you want the files to be called. For the practice trials, call this ‘practice’. For the real trials, give it the same name as the folder (e.g., P1) and/or the experimental condition. Leave all the other numbers as they are.
- Click the ‘prepare sensors and reset’ button, and wait until the word 'ready' appears in the top box. You are now ready to start testing.
- Give subject the information sheet and let them read/sign
- Assume they haven’t read it at all, and explain the task.
- "You will sit with your hands on the table with your eyes closed. I will put an object on the table in front of you, and start the computer recording. When you hear a beep, I want you to open your eyes, reach out, and pick up the object on the handle using your thumb and index finger in a smooth, controlled, and confident fashion. Lift the object a short distance off the table and hold it steady for a couple of seconds until you hear a second beep. You can then put the object back down and give a number that represents how heavy the object felt during that lift. There is no scale you need to use here - you can use 1-10, 1-100, whatever seems natural to you as long as you use big numbers to represent heavy-feeling objects. There's no upper or lower limit though, so if you need to go higher than 10 or whatever, that's fine. Negative numbers and fractions are also fine - we'll do the math to normalize your scale. This will seem like a weird task at first, but just try to rate the object relative to the last thing you lifted - if it felt a lot heavier, give it a much bigger number. If it felt a bit heavier, give it a slightly bigger number. If it felt the same, give it the same number".
- Demonstrate the lift style to them (thumb and index finger only).
- Do 5 practice trials with a non-task object(s) (with the ‘file name prefix’ set as ‘practice’), just like in the real experiment, but using the practice object. The goal here is not just to practice the lifting, but also for them to get used to the perceptual rating.
- Now get the subject ready for the real experiment – "just like in the practice trials but using different objects".
- Put the real file name (e.g., P1) in the ‘file name prefix’ box, and click the ‘prepare sensors and reset’ button.
- Start your real trials.
- When the subject gives a number to represent how heavy the object felt on that trial note it down on your protocol sheet. Make a note if anything weird happened or if you put down the wrong object (this WILL happen). Keep encouraging them at first that they are doing fine, or gently prompt them if something needs to be adjusted in their lifting style.