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Experience:  20 Years in Internal Medicine, Neurology and Sports Medicine
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The effects of cognition on the body and perceptual distortion

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The effects of cognition on the body and perceptual distortion in OCD and anxiety disorders
How does cognition affect bodily responses? For example, why does one salivate if they vividly imagine eating a lemon? If one has an impulse in OCD, why does extreme anxiety make the impulse "feel" real even if the person has no desire to carry out the act? For example, when I had harm OCD in the past, my impulses sometimes felt real, even though I knew I didn't have a violent bone in my body. Is there a relationship between adrenaline, anxiety and making something "feel" real?
Is it possible for people with OCD and anxiety disorders to suffer from perceptual distortion? Can they actually "see" things related to their obsession due to being hypervigilant (such as seeing a dead body in the road if one is worried about running pedestrians over)? What differentiates this between a hallucination? What is occuring in the brain to cause perceptual distortions?
What is the exact situation
What is the actual question about your medical situation?
Customer: replied 3 years ago.
Relist: Answer quality.
I need somebody to answer the question I asked.
Your questions are not medically focused...for example, it is unknown why an impulse feels "real", and in fact you have not defined that term medically.
If you tell me the situation I can get a better idea of what you are trying to ask...please tell me what your medical questions is, not what you are speculating about. That would be helpful
Customer: replied 3 years ago.
Relist: Incomplete answer.

The brain is essentially a central processing center for a variety of sensory data that inundates it at all times. One of its principle functions is to sort out what is real and what is only perceived. This is done primarily in the frontal lobes where executive functions reside.

It doesn't always get it right, though. :-)

This is particularly true when there is an anxiety disorder such as OCD or a severe mood disorder such as depression or a psychotic disorder such as schizophrenia. Distinguishing between these disorders can be challenging and often requires a mental health professional, particularly when there is overlap of conditions or conflation of symptoms.

Customer: replied 3 years ago.

Can you explain why certain cognitions produce certain bodily functions. I read that if one is to picture something vividly, the body will react as if the thought were real. Can the brain differentiate between what is real or imagined? Does the amygdala, for example, know the difference between real and imagined fear or will it trigger the fight or flight response even if no danger is present?

The link between the brain (cognition) and the body (sensations, autonomic function, organ function, immune function, actions) is intricate and subtle and pervasive. If something is perceived strongly in the brain, and there is no contradictory evidence to refute it, it may be accepted as real. If there is some contradictory evidence, the brain has to reconcile the differences and make a judgement about what it likely real and what is likely not real. This task itself can be influenced by one's preconceptions, biases, and bodily status, including hormonal status (e.g. adrenaline,thyroid, gonadotropins), electrolyte levels, acid-base status, etc, etc. It's a complex and complicated relationship.
Customer: replied 3 years ago.

Are there any books that would be useful for a lay reader to understand this? Would basic books on Neurology be helpful, or will books from other fiels of study be necessary?

BTW, much of what we consider real and truthful, and much of what we do and how we respond to stress and conflict and arousal, etc, is a result of conditioning. This might be from modeling of parents, teachers and other influential people in our life, or from repetition. We smell or taste a lemon and salivate enough times and we become classically conditioned to salivate even at the mere thought of the lemon (like Pavlov's dog salivating at the sound of the bell). This attests to the power or memory and imagination!
Customer: replied 3 years ago.

A couple of final questions:

Is it true one can notice certain physical sensations when one places cognitive attention on them? For example, in people who have OCD with sexual obsessions, they often report a groinal sensation to something they claim they're not attracted to. Is this because they're placing cognitive attention on that part of the body? Are they noticing sensations that always existed but were previously neutral, or are they actually causing sensations? Can fear itself cause arousal?

There was the case I read of an OCD sufferer who actually felt like he would physically strangle his father and had to keep his hands held down. Does powerful anxiety have the power to make someone act against their nature?

You could consult any basic college psychology textbook or webiste to learn about conditioning. You could also check out some of the more reliable medical websites for more about anxiety disorders, such as, or, or
As for having violent thoughts or images, especially in the context of mental illness, whether it be OCD or something more serious such as schizophrenia, this would require prompt psychiatric evaluation. I would recommend this if such thought or images are new, or have increased in frequency or severity.
Short of that, OCD is by nature an anxiety disorder, and can be exacerbated by stress, fatigue or fear. It can be like a cerebral "infinite loop" that entraps a person and creates a lot of distres. When the obsessions become compulsions, then by definition they can make one do things that one otherwise would not want to do. If one's executive functions and judgment remain intact, this may be sufficient to override the OCD...but a mental health professional should assess this and treat it promptly if there is any danger to the patient or others around him.
Customer: replied 3 years ago.

My OCD has got much better after CBT with exposure therapy. I still have some problems but cope a lot better. I'm hungry for information and am always wanting to learn.

Thanks for your responses.

You're welcome. I'm glad to hear it has gotten better. It can be a very distressing and paralyzing condition...and most people do not understand it, and do not appreciate that there is a physiologic basis for it. There is even some evidence now to suggest that in many cases it might be a post-infectious condition. Either way, keep researching and learning more. This greatly increases your chances of a good outcome.
Knowledge is power.
Best wishes.
Dr. Bob, Medical Doctor
Category: Medical
Satisfied Customers: 5657
Experience: 20 Years in Internal Medicine, Neurology and Sports Medicine
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