Previous Page

Just another rant, for no particular reason. Published in Sound Effects in 1997 I think.

Who turned on the Lights?

 

Behaviourist B.F. Skinner performed an experiment with pigeons, in which he used classical conditioning to train them to turn around twice before he fed them.  The pigeons afterwards always turned around twice before eating, even though the food was already available.  It was his contention that much of what we humans do is a conditioned rather than a rational response.  This certainly applies to sonographers, who have bucket-loads of useless and baseless habits.  It takes a true genius can transcend the paradigms and limitations of his time, and being as close to that as anyone youíll ever meet, I am going to try and defuse some of these useless habits.  There are several that currently peeve me, and a catharsis (psychologically speaking, explaining the basis of a problem can lead to its resolution, in time, at $90/hour) would be worthwhile for humanity in general and sonographers in specific.

The first of these is the dark-room scenario.  For the last two years I have been scanning in a 6th floor room, well-illuminated by two large windows, with only the venetian blinds closed to restrict the direct sunlight.  I can see the patient.  The patient can see me.  I can see the ultrasound monitor.  I can still see the ultrasound image.  It is not the brightest room in the hospital, but it is certainly not particularly dim.  If its cloudy outside (in Sydney? Never!) I even turn on the lights!  Whatís the big deal?  Why was I scanning in the dark all those years?  I have absolutely no idea.  At home, I donít watch television in the dark.  I donít turn off the lights to work on the computer.  Why did I do it at work?  Force of habit I suppose, like turning around twice before I sat down to lunch. (Finally kicked that tough one, though. Coo. Coo.) 

Obviously, no-one bothered to explain to me (and most of the medical imaging fraternity) about the dynamic range of the eye.  In everything above really, REALLY dim rooms (i.e. dark, and with 20 minutes of adjustment, like the old pre-image-intensifier fluoroscopy rooms), the rods of the eye are fully saturated and we see with the cones anyway.  We are looking at our black and white images with our colour vision.  Any potential for a gain in grey-scale detection in the normal range of daily activities is mythical - literally sub-liminal.  The rodsí main use in daylight is related to motion detection - the corner-of-the-eye phenomenon.  Turning the brightness of the monitor up a bit is EXACTLY the same as dimming the room lights as far as the brain is concerned, so long as the average ambience remains the same.  The eyeís dynamic range responds to the whole field of vision, not just what you are looking directly at in the field of a few degrees of arc. Even if the room is dark, the brightness of the monitor will saturate your black and white rods.  I do not get headaches in my well-lit room, as the relatively uniform light from the background to that emitted from the monitor, creates no stress on the old 'ocularities'.

The real problem with viewing monitors is related to unwanted reflections.  Headaches can result from your brain continually trying to refocus your eyes onto the reflected image.  Obviously room design and machine placement will affect the feasibility of this.  In fact I find dark rooms with bright monitors particularly tiring on the eyes. 

Your patients will appreciate it and youíll see them in a new light (predictable and unilluminating pun, sorry.)  It also reduces stress in the minds of the patients, who have take off most of their their clothes and go into a dark room with someone like you.

 

Phillip L RAMM.