Subject: Willingness to hear speach / tones ins noise From: Christian Kaernbach <auditory@xxxxxxxx> Date: Sat, 25 Mar 2006 09:25:30 +0100Dear 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