The influence of semantic top-down processing in auditory verbal hallucinations.
BACKGROUND
Auditory verbal hallucinations (AVH) are one of the most prominent symptoms of schizophrenia but have also been reported in the general population. Several cognitive models have tried to elucidate the mechanism behind auditory verbal hallucinations, among which a top-down model. According to this model, perception is biased towards top-down information (e.g., expectations), reducing the influence of bottom-up information coming from the sense organs. This bias predisposes to false perceptions, i.e., hallucinations.


METHODS
The current study investigated this hypothesis in non-psychotic individuals with frequent AVH, psychotic patients with AVH and healthy control subjects by applying a semantic top-down task. In this task, top-down processes are manipulated through the semantic context of a sentence. In addition, the association between hallucination proneness and semantic top-down errors was investigated.


RESULTS
Non-psychotic individuals with AVH made significantly more top-down errors compared to healthy controls, while overall accuracy was similar. The number of top-down errors, corrected for overall accuracy, in the patient group was in between those of the other two groups and did not differ significantly from either the non-psychotic individuals with AVH or the healthy controls. The severity of hallucination proneness correlated with the number of top-down errors.


CONCLUSIONS
These findings confirm that non-psychotic individuals with AVH are stronger influenced by top-down processing (i.e., perceptual expectations) than healthy controls. In contrast, our data suggest that in psychotic patients semantic expectations do not play a role in the etiology of AVH. This finding may point towards different cognitive mechanisms for pathological and nonpathological hallucinations.
Department of Psychiatry, Neuroscience Division, University Medical Center Utrecht & Rudolf Magnus Institute for Neuroscience, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. K.Daalman@umcutrecht.nl
Kirstin
K
Daalman
Sanne
S
Verkooijen
Eske M
EM
Derks
André
A
Aleman
Iris E C
IE
Sommer
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006212:Hallucinations / Q000175:diagnosis* / Q000523:psychology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010469:Perceptual Distortion; D011569:Psychiatric Status Rating Scales; D012660:Semantics; D011795:Surveys and Questionnaires