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Allison M McKendrick, David J Lawson, Andrew Turpin; PsyPad: an iPad application to enable vision research. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5600.
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© ARVO (1962-2015); The Authors (2016-present)
Tablet computers (such as the iPad) have potential to be used for vision experiments. A key advantage of iPads is their portability, allowing experiments to be easily taken outside the lab. However, a major barrier to using iPads for vision experiments is the knowledge required to program an app. A second barrier is that the iPad has no accessible file system, so recording and transferring results from the iPad requires non-trivial programming. The aim of this study was to develop a point-and-click interface to customising visual psychophysical experiments on the iPad.
We developed the app, named PsyPad, to have built-in staircase and method-of-constant-stimuli (MOCS) procedures that are customisable by a menu interface. Staircases can be interleaved with step-sizes customisable. Visual stimuli are provided by the user as a zip-file of images. Up to 4 response buttons can be customised for a test. All participant actions are logged (including response times), and results and log files sent to a central server. To test the app, we loaded image sequences for a global motion detection task (8 frame random dot motion sequence) and a global form detection task (Glass pattern coherence thresholds, and configured a interleaved staircase procedure using the point-and-click inferface on the server (2 staircases, 6 reversals, 3up-1 down). Stimuli were designed to be the same as in McKendrick et al, IOVS, 2005: 46: 3693-3701. These were tested on 3 observers with normal vision who used the app unsupervised for 7 days in succession.
Configurable global motion and form tasks were implemented using PsyPad. The thresholds obtained were not different from those collected on a standard laboratory visual psychophysics set-up for the same observers and were consistent with previous literature. The mean (+/- stdev) global motion coherence thresholds (% signal dots) for the 3 observers were 8 (3), 13 (6) and 9 (6) % coherence. Mean (+/- stdev) glass pattern coherence thresholds (% signal dipoles) were 8 (3), 15 (4), and 30 (11) % coherence. PsyPad is available on the Apple AppStore, and we provide a server at http://www.psypad.net.au/server for use in research studies.
PsyPad is a free iPad app that allows customizable visual psychophysics tests on the iPad without the need for iPad programming. As the iPad uses LCD touchscreen technology, care should be taken if using PsyPad for tasks where precise timing is required.
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