[visionlist] observer rejection query

[Julie M. Harris]

A query to all psychophysicists, and especially to those working in binocular
vision.

We are working on a study using a large number of totally naive observers
(dozens of people rather than 3-4).  We're finding that many cannot achieve
threshold in a binocular vision task, sometimes around 25% of people.

That sounds like a lot, until you start sampling the psychophysics literature,
where binocular vision (and other) studies often report that 'observer X was
rejected because they could not do the task'.  With just a handful of
observers, losing 1 _could_ really reflect 25%.  Question is: HOW MANY people
typically can't do these tasks?  I'd like to work out a reasonable expectation
for the proportion of observers who deliver unusable data (whether reported in
publications or not).

I'd be very pleased if you could let me know your own experiences from your lab
studies (or others you may know of).

I will summarise any responses and post on visionlist.

regards

Julie Harris

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Julie M. Harris
Professor of Psychology
School of Psychology
University of St. Andrews
St. Mary's College
South Street
St. Andrews
KY16 9JP

Julie.Harris at st-andrews.ac.uk



The University of St Andrews is a charity registered in Scotland : No SC013532


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