Touch-screen phone versus push-button mobile

August 02, 2015 05:00 pm | Updated March 29, 2016 12:44 pm IST



Those were the days of stenographers and typists, and manual typewriters at every office. And there used to be competitions for speed-typing. Our stenographer at Centre for Cellular and Molecular Biology, the late Mr. Ramarao, was a champion, typing away at break-neck speed. Well, those days are gone. Most of us today are our own typists, touching away text message and emails at our PCs or tablets, or gripping the Smartphone with the right palm and using the right thumb with great rapidity. Not everyone has a touch-screen phone. Many still use the old-fashioned ones, where you have to push buttons for each letter or number. The way the two grip the phones and enter the characters is quite different. How then do their touch-sensitive (tactile) areas of the brain differ from those of the touch-screen-wallas? Just as what we see is captured and processed in the brain by the visual cortex, the region called the somatosensory cortex receives and responds to tactile signals. This question of the difference between those who use touch-screen devices and those who are still ‘classical’ has attracted the attention Dr. Arko Ghosh and colleagues at the University of Zurich, Switzerland. They note that touch-screen phone screens demand repetitive finger movements. But whether and how the somatosensory cortex conforms to this is not known. To this end, they analysed how the cortical processing of signals coming from fingertips in touch-screen phone users differs from ones from those using traditional old-fashioned phones.

How the brain registers and reacts was monitored by placing a tight-fitting skullcap with over 62 surface electrodes distributed over the entire scalp. This helped detect the electrical signals evoked by touch on the thumb, index and middle fingers of the right hand. (Note that the phone is grabbed by the entire palm, with the first three fingers clutching it, while the thumb touches the various letters and numbers.) Thirty-seven right-handed volunteers were analysed, of whom 26 had touch screen phones and 11 had old technology mobile phones.

Several results came out. One was that the touch-screen phone users spent far more than with their phones than did the non-users. And they relied mostly on their thumbs to interact with the screen. Yet, the electrical potentials recorded on the somatosensory cortex associated with the first three fingertips were higher than those in non-users.

Is this because of a more intense use of the hand or due to greater “skill” to touch than to push the buttons in the old technology by mobile phones? To check this, the researchers looked into the time used by the batteries of the phones and found that the cortical signals were directly proportional to how much each person used his or her phone. The more they used the thumb, the greater this signal.

But does practice make perfect, like what is seen in, say, musicians? Apparently not. The thumb signal measurements fluctuated. The greatest response was seen when the telephone was most recently used; it was not a linear or cumulative build-up as with musicians, but depended on recent use. Musicians start an early age, and go through disciplined practice. For touch-screen phone users, if appears more like a “temporary reallocation of neuronal resources.”

The price you pay

Alas, the downside for Ramarao was recurrent pain in his right forearm and wrist. Doctors call this the Carpal Tunnel syndrome, a muscular fatigue and consistent pain resulting from an excessive use of the wrist and fingers. He had to be rested often and given painkillers and physiotherapy. His speed came at a cost.

The modern day avatar of this is seen in youngsters. Researches at the University of Waterloo, Canada, studied 140 university students and found 84 per cent of them had pain in at least one part of the body related to the time spent on browsing the Internet; and with the touch-screen phone users, the pain was most common in the thumb. And Hazel Parry, in her article “The curse of iPhone” in China Daily of Hong Kong, points out that many constant users who arch down their necks to read their touch-screen phone screens suffer from bad posture, and pain in the wrist and neck (called Tech-neck) and “Blackberry Thumb.” The worst is to use smart phones while travelling in subways and local trains. This affects your balance and eyesight as well; Parry compares Tech-neck with Tennis Elbow or Washerwomen’s Sprain.

Ghosh and colleagues propose in their above paper (published in Current Biology , on January 5, 2015) that “cortical sensory processing in the contemporary brain is continuously shaped by the use of personal digital technology”. Well, not only sensory processing but sensory pain as well.

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