Re: [AUDITORY] Matlab Code for interleaved adaptive procedure

[Owen Brimijoin <owen@xxxxxxxxxxxxx>]

Dear Emmanuel and the List,

I have something that might help. A while back I realized I was wasting 
a little time with each new experiment I built, scratching my noodle 
over the rules governing what to do with a signal in an adaptive track. 
I wanted a simple function that was flexible enough to cover all the 
usages I could think of, because let's face it, each time we want to 
measure some threshold we always need something to be a little bit 
different, right? That said, there's one thing that's always the same, 
namely the need to know what to do with the signal on the next trial. Do 
I increment the level? Decrement it? If so by how much? Do I leave it 
the same? When is the track 'done?'

To solve these pesky recurring problems, I wrote a compact function 
called adaptive_track_engine.m and posted it on the Mathworks file exchange:

http://www.mathworks.co.uk/matlabcentral/fileexchange/40892-adaptive-track-engine

You give it the history of the listener's answers up to that point, the 
step sizes and number of reversals you want in each stage, and any 
arbitrary adaptive rules (like 3 down 1 up or, equally, something 
bizarre like .. say... 2 down 6 up). It returns what you need to do to 
the signal on the next trial and tells you when the track is finished. 
Simple as that. I've added an example for how to use 
adaptive_track_engine to do multiple interleaved tracks in the zip file 
on that page.

It's important to note that this is NOT a ready-to-play psychometric 
threshold estimation program. If that's all you want, there are any 
number of commercial or free standalone complete programs available 
elsewhere. The idea behind this function was to be as flexible as 
possible so that it could be used in *any* custom adaptive track 
program. The core function also allows scalar output, making it flexible 
enough to use in, for example, an adaptive minimum audible angle 
measurement too (to change degrees instead of dB). Not incidentally, I'd 
be awfully grateful if any of the readers of the Auditory List had 
suggestions for how to improve its flexibility.

Best of luck and I hope this helps!

-Owen.

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W. Owen Brimijoin
MRC Institute of Hearing Research
Glasgow, United Kingdom
owen@xxxxxxxxxxxxx
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