Source Monitoring Deficits Detected in Schizophrenia

Hallucinations are a common symptom of schizophrenia. Some clients experience auditory and visual hallucinations (AVH), while others experience olfactory hallucinations (OH). Although both types of imagined experiences can be frightening and disturbing, OHs are particularly unpleasant because clients who have OHs often report smelling very bad smells that cause them to be quite distracted and agitated. Understanding the processes that cause AVH and OH and why some clients exhibit both types of symptoms while others only exhibit one were the focus of a recent study led by Deborah Arguedas of the ARC Center of Excellence in Cognition and Its Disorders at Macquarie University. Arguedas examined source monitoring and the ability to determine the source, either real or imagined, of stimuli in an experiment conducted with 26 schizophrenic clients with either AVH, OH, or both and 27 control participants.

After a series of experiments in which the participants were exposed to several different scents, Arguedas found that the recall of the frequency of the scents was significantly skewed in the clients with OH. Specifically, the clients with OH believed they had smelled the scents many more times than they actually had. Additionally, they were particularly sensitive to the bad odors and reported excessive numbers of exposure during recall, which far exceeded the actual number of times the scent was administered. The AVH clients also experienced increases in imagined frequency, but not as severely as those with OH. Both groups however, had many more imagined scent exposures than the control group did during the recall portion of the experiment.

Arguedas believes the results of this study demonstrate a clear presence of impaired source monitoring abilities in the participants with schizophrenia. During the auditory task, the AVH clients showed higher levels of imagined recall than the OH clients; however, the levels were not as high as those in the previous task. Therefore, the study implies more significant impairment in the source recognition abilities of individuals with schizophrenia and OHs than in those with AVHs alone.

Arguedas, D., Stevenson, R. J., Langdon, R. (2012). Source monitoring and olfactory hallucinations in schizophrenia. Journal of Abnormal Psychology. Advance online publication. doi: 10.1037/a0027174

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  • Linsey


    March 23rd, 2012 at 11:22 AM

    Yuck! Smelling gross smells that aren’t even there? That must be unpleasant to say the least!

  • Nic


    March 23rd, 2012 at 5:00 PM

    Sorry, but hearing and seeing things is sure gonna freak me out more than smelling stuff. I mean you can hold your nose but it would be tough to shut those voices out or to stop those hallucinations. And I have to tell you that this is the first time I have ever even read anything about having these olfactory hallucinations so to speak. That just is not the typical picture of the schizophrenic we have been given.

  • janey few

    janey few

    March 24th, 2012 at 4:59 AM

    so do traditional drugs for schizophrenia help with OH as well as AH or are there different treatment tracks for this?

  • Jeanna


    March 25th, 2012 at 6:09 AM

    Umm…but that is what a “hallucination” is isn’t it?seeing,hearing or smelling things that aren’t there?now why the hallucinations are more prevalent for one thing than the other is interesting but irrespective of how pronounced it is,the problem being present is what is important,if I’m not wrong(?)

  • Gary O'Connor

    Gary O'Connor

    April 4th, 2012 at 10:15 AM

    For me it is the phantom smells that trigger my complex partial siezure,or they are the early warning signs that I’m about to have one. When I now smell something strange,I will now ask the people around me if they smell something, if they say yes. I ask what does it smell like? If the 2 discription of the smell do not match, I maybe starting to have one. But my experience as of date, has been If I smell something strange for no explanation or reason, I know I’m about to have one. I then try to get myself to a controled place like my home. If I’m driving I find a place to park my car & I call my wife. Yes I take medication for this, but they still at sometimes push thru the med’s even with the max dosage being taken. The syptoms / feelings can be scary for my friends, family, aswell as me.. It is hard to explain to them what I’m feeling. I do forget thing,s but do not relize that I have forgotten anything. {How can you know that you forgot something if you can’t remember it to begin with]It is only when someone says do you remember this or that, do I even think about the memory loss. Thanks for letting me share my thoughts.
    Hope I’m being more helpful than hurtful.

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