The oddball paradigm is an experimental design used within psychology research. Presentations of sequences of repetitive stimuli are infrequently interrupted by a target stimulus. The reaction of the participant to this "oddball" stimulus is recorded for further analysis.
This version of the Oddball is based on iOS and Arduino, in order to be able to easily run the experiment in outdoor or in mobility.
This project is completely open-source, can be modified and re-distributed. Find us on line on www.github.com/theskinnerbox/oddball.
A video introduction to this app is available here: https://youtu.be/Z5xqu-9OOjE.
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How it works
The system consists of two elements: an iOS app and an Arduino device.
The iOS application generates two types of audio stimuli: target (high pitch) and standard (low pitch). The participant is requested to give a response just after a target stimulus, but not after a standard stimulus.
The participant can give the response in two ways:
- through the app
- with an external switch connected to the iOS device through an Arduino Yun
Duration is measured in milliseconds from stimulus to response; cases of missed target are also recorded.
Output data is saved as a CSV file. Stored files can be moved to your computer using the “File Sharing” tab in iTunes.
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Design considerations
The app design is minimal to reduce the visual attention of the participant.
Black screen reduce noise in low light conditions.
Tap on the bottom slider to start or end a recording session.
A session ID is requested to help participant and experimenter in settings and data analysis.
The central part is occupied entirely by the button that serves the participant to respond to the stimulus.
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Settings
Access to the settings pane through the info button on the bottom right.
One of the characteristics of this application is the high degree of configurability, which makes it suitable to various experimental needs.
A powerful feature is also that you can try the parameters “live” through the "Play" button on the top left. It allows you to quickly experiment with various configurations.
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External trigger with Arduino Yun
The external trigger is composed of an Arduino Yun board connected to an external physical button.
The button can be any momentary button. In this case, it is a foot pedal to allow participant response in cases where the primary task requires the use of both hands.
iOS and Arduino are connected together through a WiFi network.
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Enjoy!