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The Wisdom of Psychopaths
In this engrossing journey into the lives of psychopaths and their infamously crafty behaviors, the renowned psychologist Kevin Dutton reveals that there is a...
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What if your brain knew something but couldn’t tell you? New research suggests that this is exactly what may be behind two rather curious conditions.
Most of us are familiar with people who are tune deaf – these are the people who not only cannot sing in tune but are also unaware of that fact. Individuals with severe forms of this condition, known as amusia, are unable to detect whether particular notes within a melody are out of tune or out of key. Many are also unable to recognise melodies without lyrics or to hold a tune in their heads, even if they have just heard it. These difficulties arise despite normal hearing and also a fairly normal ability to hear the difference between isolated tones. The defect lies in connecting this sensory input with some implicit knowledge of musical structure and contours. Amusia thus falls into a class of conditions known as agnosias, which are characterised by the lack of knowledge of some, often very specific, category of object.
Another, equally curious, example of this class of condition is prosopagnosia – the lack of knowledge of faces. People with severe prosopagnosia may be completely unable to recognise the faces of famous people, friends, loved ones, even their own faces. As with amusia, this reflects a high-level deficit – people with prosopagnosia have normal vision and the ability to distinguish specific facial features, gender, even facial emotions. Both conditions thus seem to reflect the inability to link incoming sensory information (a person’s face or a specific note) with stored, implicit knowledge about that category (the person’s identity or a specific melody or general rules of melodic stucture).
At least, that is how the defects manifest at a behavioural level. It had been predicted that this defect would also be apparent in the normally highly selective responses of brain areas that are specialised for processing music or faces. Yet recent experiments suggest that the underlying defect lies not in the responses of these specialised areas, which are still highly selective, but in how these responses are communicated to higher brain centres.
In one telling experiment into the neural basis of amusia, subjects were connected to an electroencephalography (EEG) machine to measure the electrical responses of different brain regions. In control subjects, notes that are out of tune or out of key induce a specific, easily detected EEG response after about 200ms. When the experiment was done with amusia subjects, exactly the same response was found. Their brains were just as sensitive to discordant notes as those of controls. However, a later response, around 600ms, was almost completely absent. This later response likely represents the communication of the detection of a discordant note to higher brain areas, which are responsible for the conscious awareness of that event.
This conclusion is strongly supported by the results of functional and structural neuroimaging experiments. In people with congenital amusia, frontal areas are more weakly coupled to posterior auditory areas. These findings thus suggest that the brains of people with amusia can detect discordant notes just fine – the people are simply not aware of it. Their brain knows but their mind does not.
Very similar effects have been observed in neuroimaging experiments of people with prosopagnosia. Normally, the activity of a brain area in response to a specific stimulus (such as a particular face) will decrease with repeated presentations, but will increase again in response to a new example from the same category (a new face). If the brains of prosopagnosics are really unable to discriminate between different faces then the increase in response to a new face should be absent. In fact, the “face areas” of prosopagnosics are still quite sensitive to differences in facial identity. What is different is that these responses are not communicated to areas in the frontal and parietal lobes, where conscious awareness is triggered.
These results are consistent with studies which use galvanic skin responses to detect emotional responses. These studies have shown that even though prosopagnosics may not consciously be able to distinguish a loved one’s face from a stranger’s, they still experience a specific autonomic response when shown a loved one’s face. Again, structural neuroimaging supports the notion that the reason for this failure in communication lies in a structural disconnection – a reduction in the nerve bundles linking these areas.
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9 Comments
Add CommentI wonder whether or not something quite similar might be behind certain social pathological behaviors. The person has empathic neurons which still respond negatively to the harm being done to another, but those responses are not effectively communicated to the brain's moral processing areas.
Reply | Report Abuse | Link to thisI think you may have something there. I wonder if it is possible that in a few cases the connections are made to the wrong areas as well because a few people such as a couple of well know killers have a history of totally inappropriate emotional responses.
Reply | Report Abuse | Link to thisI find this fascinating because I can't carry a tune or hear when I'm off key. I also have a terrible time staying in rhythm when dancing. This is why I don't sing or dance when others are around. I also never sing around dogs because it seems to spark an attack response even in normally friendly dogs.
Reply | Report Abuse | Link to thisThere is indeed a strong parallel between the kind of disconnection syndromes I discuss here, which affect perceptual processes, and what is proposed as the underlying defect in psychopathy. Imaging research suggests a disconnection between areas involved in empathy, conscience and impulse control. See the following for more information: http://wiringthebrain.blogspot.com/2010/02/bad-to-bone-altered-connections-in.html
Reply | Report Abuse | Link to thisThese observations are entirely consistent with my completely different model of how the brain works, introduced at www.scienceuncoiled.co.uk, where you will find a summary, my book and a compilation of recent supporting evidence and research proposals. Questions to michaeltdeans@gmail.com welcome.
Reply | Report Abuse | Link to thisMy son has an interesting variation of tone deafness and I am wondering how the author would explain it. He has perfect pitch in that if he hears any note he can tell you exactly what it is. However, he cannnot carry a tune at all when singing.
Reply | Report Abuse | Link to thisMy daughter has prosopagnosia, and she is not tone-deaf, not by a long shot. I don't know if she has perfect pitch, but I do know that she has good tone and a beautiful singing voice. It does not take long for her to learn a song and sing it well.
Reply | Report Abuse | Link to thisI am bad at carrying a tune, and even worse at matching names of people to their faces. But if I focus really hard, I can detect if a tune is off (but cannot sing it right despite that). Similarly, if I only meet five or less new people in a day, I can remember all their names. Bring on a sixth one, and I lose them all. I've noticed that the problem seems to be that when I have to sing, I have a 'different' tune in my head to sing to, and there is almost never any way to get the 'right' tune back into the storage section for that tune. Ditto with names. I often store the wrong but similar name, and no amount of mnemonics seems to help. If I get any of these right the first time, there is never any problem later. Usually, it helps if I see the name of the person first, and then see the face. Similarly, if I hear the instrumental part of the tune first, before the song.
Reply | Report Abuse | Link to thisI know several people, including my young granddaughter, who can sing reasonably well in tune as long as they are singing solo. As soon as someone else joins in, however softly, they 'lose' the tune and the singing becomes a tuneless monotone - and they have no realisation of the fact. I'd love to help my granddaughter as we come from a community in which singing is a 'part of life' and her peers are beginning to make fun of her voice. Does anyone have any explanations as to why the perception of a tune is 'drowned out' as soon as someone else joins in? Is there any training which would help?
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