Willingness to hear speach / tones ins noise

[Christian Kaernbach <auditory@xxxxxxxxxxxx>]

Dear List Members,

This is a quest for hints to good literature on auditory hallucinations 
as a personal trait. Here comes our background:

We are going to study the "willingness" of participants to hear speech 
or even just tones in noise. This is in analogy to the visual 
experiment, seeing faces or a letter in visual white noise, see e.g.
	Gosselin F, Schyns PG (2003).
	Superstitious perceptions reveal properties of internal
	representations. Psychological Science 14 (5): 505-509.

We are not interested in the nature of the internal representation but 
in the willingness to see/hear a meaningful stimulus in noise as a 
personal trait. Therefore we think we can do with far fewer trials than 
studies that want to come up with the "superstitious percept". 
Furthermore we are not bound not to bias the participants; we could in 
addition to pure noise stimuli also present "signal stimuli" that 
contain noise plus some real material (speech, tones). This would make 
it a "real task", avoiding the risk that participants get suspicious. 
The signal to noise ratio in the signal trials could be adapted 
beforehand so as to have a low but above chance performance. --- In the 
end we might be interested to compare the willingness to perceive a 
meaningful stimulus in noise across modalities, and/or to compare it to 
verbal association tests, creativity tests, a magical ideation scale, 
and behavioral data in experiments known to discriminate between magical 
thinkers and skeptics.

We are aware of literature on auditory hallucinations in schizophrenia, 
including imaging studies. We would be highly interested in literature 
on auditory hallucinations in healthy persons (with or without imaging), 
on auditory hallucinations as a personal trait (again in the realm of 
healthy persons), and - if this method has ever been used - on what 
could be called "provoked auditory hallucinations", i.e. presenting real 
signal plus noise stimuli among pure noise stimuli like in a signal 
detection task, making it really hard not to produce false alarms, and 
interpreting the "detection criterion" as a personal trait.

Anecdotally we have observed something that could be called 
"superstitious perception" when doing simple up-down (Békésy) adaptive 
threshold measurements of a sinusoid in noise. We had three participants 
who simply could not determine a threshold with this procedure. They 
would say "But I know that there is a sinusoid, and I always think I 
hear it. I don't know when to stop to say 'Yes'." They stopped saying 
'Yes' only because they knew it would not end otherwise. Their results 
with this procedure varied enormously between sessions. See Fig. 8b in
http://fechner.uni-graz.at/team/kaernbach/publications/2001a_kae_p&p.pdf

Best regards,
Christian

--
Prof. Dr. Christian Kaernbach
Psychologische Methodik und computergestützte Modellierung
Institut für Psychologie
Karl-Franzens-Universität Graz
Schubertstr. 51 a
A-8010 Graz
Austria
www.kaernbach.de fechner.uni-graz.at