Holcombe:Optacon

SUPA Sydney University Perception and Action Lab Primer editing help refcard

THE OPTACON

SUPAlab is currently home to an Optacon. The optacon has been used to run experiments on tactile motion perception. It occupies two desks in the main area of SUPAlab. Hence, this years honours students have been forced out of the lab to make room for the machine. They are sorely missed for their great sense of humour and amazing artistic abilities.

Overview of set-up

• Tower+Monitor uses “Optacon Stimulator” software to provide input to Optacon Interface (the rectangular box with the TRS connectors/jacks).
• The Optacon Interface uses input from Opticon Stimulator to drive the optacon
• Powerlab box reads from Optacon Interface
• Response buttons are connected to the Powerlab box
• Laptop with Labchart collects the output from Powerlab box (button presses and signal from pins)

Switching on the system

• Turn on the computers
• Turn on Powerlab box (switch at back next to grey cord)
• Turn on Optacon Interface (switch on top of box where it says Power)
• Optacon should be the last thing you switch on

Switching off the system

• Optacon should be the first thing you switch off
• Then switch off the Optacon Interface + Powerlab box
• Then switch off computers

Input to Optacon interface

• The tower+monitor provides input to the optacon interface

• Open Optacon Stimulator
• Create New or Open
• Uses .txt files – can make these in excel etc.
• Array (frames) is the input
• Dwell time – how long it stays on that frame
• Pins have fixed vibration rate
  • Single protraction/retraction is 4.35ms for ~230Hz vibration
• Dwell time specifies how long the pins vibrate in the arrangement of that frame
  • Note: Should take into account 4.35ms “frame duration”
    • e.g. if you put 5ms, It will do 2 protractions/frames, actually taking 8.7ms

• OR Click on cells to manually change them

• In array/frames for input: specify number of Blocks and Stimuli
• Blocks are like the Folder
  • Stimuli are within blocks
• Can repeat blocks or stimuli independently

• In the input window for the pins
  • ANIMATE – can visualize how the pins are moving
  • Switch off animate when running experiment
    • Can cause lag if it is switched on
  • LOOP – will repeat whole sequence including blocks, stimuli – toggle on/off

• First 5 seconds of task should be empty –
  • Might be vibrations due to noise etc, so have first 5 seconds empty to ensure experiment starts off clean

• Powerlab box
  • Can choose which pins the Powerlab box records from

Data Collection

• Laptop has Labchart on it
  • Uses this for data collection

Starting Labchart:

• Labchart shortcut is on the desktop
• When labchart loads it will seach for optacon interface
  • If optacon interface is powered off you can still load labchart
    • e.g. if you want to look at data
  • If you want to use it with the optacon interface make sure interface is on first

• To use settings that have been made for use with optacon:
  • Open a template (e.g ‘example’)
    • Then: File – new – will ask if want to use settings based on other worksheet – click ‘yes’

Testing if everything is connected properly

• Make a file that shows the button presses and the pins you are interested in recording from
• Run and check if button presses and pin recordings correspond to the correct channel
  • e.g. Pin input test – test everything is plugged in properly

Recording:

• Press START button in the bottom right hand corner to start recording
• Top 3 channels shows input – i.e. response from pressing buttons
• Bottom 3 channels records from pins
• Can toggle MONITOR to the left of start button – it will monitor responses/input but doesn’t record
  • Make sure it is off when you want to collect data
    • Monitor Off / Recording– Not showing red X
    • Monitor On / Not Recording – Showing red X

• Can also set up new channels to calculate things from the other channels

Saving:

• Save raw data as an .adicht file before doing anything
• Can select data points – ‘save as’ data file

For stats:

• File – export – labchart txt file

• Samples at 10k a second – can downsample it for smaller file size - this may reduce precision of optacon pins because they are very fast (so find a suitable sampling rate for your purposes)

Notes for running subjects

• Instruct participants that they do not need to press hard on buttons
  • Feels like it isn’t registering but it is
• Use scales to measure pressure on fingers
  • Keep this constant over conditions and participants
  • If pressure is too high – will dampen the vibrations – should be gently touching

Misc notes

• Pull out blue cord at back of optacon to use the visual input part of the optacon
• Switch at back – INVERT – black on white or white on black
• Make sure optacon is not resting on the array – can damage the pins
• ALWAYS BE CAREFUL – it is a fragile piece of equipment we can’t easily replace