Sensory Gating and Improvisation

It is rather surprising how often psychologists inadvertently come up with  poetic terms to describe their discoveries. One such term in neuroscience is, ‘sensory gating’. When a human hears a sound their brain responds rapidly, peaking at around 50 milliseconds (P50). The minute electrical currents generated by that response can be measured and plotted onto a graph. The graph looks like this:

P50 waveform of sensory gating
P50 waveform

When the same sound keeps repeating, with a short gap of about half a second between, the height of the P50 peak progressively reduces, resulting in a flattening of the response curve. It is a strangely counter-intuitive concept:  the higher the level of sensory gating, the flatter the response curve.

‘Sensory gating’ is a kind of habituation effect. Some writers link this phenomenon to the theory of ‘fight or flight’. The brain, they claim, makes an involuntary response to any sound, evaluating it as a potential threat. When we hear the same sound several times, the curve begins to flatten, and the brain no longer perceives the sound as threatening.

Lower sensory gating

Although the vast majority of people exhibit similar levels of sensory gating, a small minority display reduced levels. Instead of becoming habituated, they respond to repeated instances of the sound with a similar intensity. Schizophrenics are one social group that have particularly low sensory gating. Their elevated anxiety is thought to constantly trigger the ‘fight or flight’ response. There is, however, another group of people who have also been shown to have lower levels of sensory gating: musicians.

I came across all this when, as a psychology technician. I was trying to learn how to implement electroencephalography (EEG) experiments. An ‘auditory response test’ was the simplest EEG experiment that I could try to do.


It was when I tested myself that I received a surprise. It seemed that I had a surprisingly low levels of sensory gating. I began to wonder if this was linked, not to any unacknowledged schizophrenia, but to my practice regime as a musician. Instead of practicing the scales, arpeggios or jazz patterns I should probably do, I often just wear headphones and improvise along to whatever I am hearing. You could call it intensive ‘ear training’, done on a daily basis.

I started to wonder: does improvisation, in particular, develop a specific attentiveness to sound, even to the extent that it can supress sensory gating?  Many orchestral musicians play written music and never improvise. Improvisers, by contrast, rely solely on their ability to  make an instant response to sound. Classical musicians could counter that they are equally responsive to the details of sound. They might highlight how they modulate their volume, tone, articulation and expression to the requirements of the music. Would sensory gating  be lower amongst improvisers than amongst orchestral musicians?


I haven’t found any studies that have examined this. I suspect that it might be true, but only a detailed, large-scale experiment could conclude that it was. A study of dancers, musicians and ‘lay people’ comes close. Dancers display the kind of reduced sensory gating that one might expect from improvisers.

Functional Growth

Hercule Poirot boasts about the number of ‘little grey cells’ associated with his powers of deductive reasoning. It is interesting that musicians can make a similar claim for their craft. Professional musicians  have enhanced ‘functional’ growth in those areas of the brain associated with listening and dexterity. Did this ‘growth’ develop as a result of practice regimes, or did it precede and condition their musical abilities? I can’t help wondering if we would discover a slightly different distribution of ‘little grey cells’ amongst dedicated improvisers?

What hapens next?

For a time, I contemplated the idea that I might do this research myself: after all, I know so many improvisers. However, time passed and I eventually stopped working as a psychology technician. So, if someone stumbles across this post who would like to discover the answer to these questions, but also has access to the appropriate research equipment, please do let me know. I suspect that volunteers would not be hard to find.

Why I wrote ‘Mirror Trick’

As a teenager, I was in love with the romance of literature. I adored to write descriptive prose, full of complex similes. Then, around the age of eighteen, I was influenced by the improvisatory style of the Beat writers – Kerouac, Ginsberg, Ferlinghetti, Burroughs. My writing changed. The similes were replaced by rhythmic disjunctions, sudden shifts of register. When I read my texts from this period, I am amazed at their energy and bravura. I couldn’t write like that now, even if I wanted to.

Does anyone write letters anymore? I don’t. Back then, letters were the main vehicle for my writing. Pages and pages of thoughts and ideas. Suddenly people were calling me a ‘wordsmith’. I heard this word used about me over and over again, throughout my life. I would write art project proposals, promotional blurbs for musicians, texts for protest campaigns, and people would complement me on my writing. Yet I had abandoned poetry and I felt that I had nothing to contribute as an author of fiction.

My reading habits had changed too. Instead of reading works by authors who pushed at the boundaries of form, I read a lot of crime books. For a time, it became an addiction, following particular authors until I had read everything that they had written. Aware of the volume of light reading that I was consuming, I felt the need to balance my reading habits. I regulated the amount of crime books that I was reading, interspersing them with works by modern authors and the classics.

What was it that finally brought me to write ‘Mirror Trick’? In part, it was brought about by a huge change in my life. I stopped working – I had been working in a psychology department, providing specialist technical support to students and researchers. At exactly the same time, I moved from London to Lisbon, in Portugal. I started to reassess my previous conviction that I had nothing to contribute, no voice that was really my own. If that was true, why did I play improvised music? If I had no legitimate voice as a writer, why did I dare to venture onto the stage as a musician and perform at every available opportunity? You can’t do that and believe at the same time that you have nothing to say.

So, the barest outline of a plot for Mirror Trick began to suggest itself to me. I could combine my love of crime fiction with the smatterings of knowledge that I had picked up from working with researchers in psychology. As I started to write, I began to realise that the mere fact of being alive has provided me with an inexhaustible canvas of the characters that I have met along the way. It’s not just your own voice, but their voices too, that you are expressing. Then, why not create new, composite characters, blending together bits of one person with bits of another? So obvious – but so oblique and inaccessible – that is, until you try to write.

So, where is my earlier fondness for the Beat writers? Where is the experimentation with literary form? It appears that this occupies a much lower position on my scale of priorities. The crime novel, with its relatively stilted conventions, provides me with sufficient scope to express all manner of ideas. The genre is sufficiently elastic to be able to include tentative experiments with form, subtly introducing stylistic innovation. The only thing that it generally can’t do, is to transcend the expectations of its readers. Above all, this story allowed me to explore my feelings about the country where I no longer live. That country is at the heart of ‘Mirror Trick’ – the characters inhabit its locations, its figures of speech, its weather – it permeates everything, even the experiences of the Polish professor who is the central character of the book.

It is too early to say that I have ‘found my voice’. Time will tell whether that is true. All that I can claim for now, is that I have told a story, and that in doing so I found a way to incorporate a very small portion of the things that constitute who I am.