太過專注使人“無意失聰”

Becoming engrossed in a good book or a crossword really can block the ability to hear, a study has found.

Scientists demonstrated that when someone focuses their full attention on something, they can become deaf to normally audible sounds. It happens because visual and hearing senses are trying to share limited brain capacity, they said.

But it can have serious consequences, and could be the cause of some road accidents. The phenomenon is known as "inattentional deafness".

Study leader Professor Nilli Lavie, from the Institute of Cognitive Neuroscience at University College London, said: " 'Inattentional deafness' is a common everyday experience. For example, when engrossed in a good book or even a captivating newspaper article, we may fail to hear the train driver's announcement and miss our stop. Or if we're texting while walking, we may fail to hear a car approaching and attempt to cross the road without looking."

In the study, 100 volunteers performed computer tasks involving a series of croSome were easy, such as being able to tell that the arms of the cross were different colors. Others were more challenging and involved identifying subtle length differences.

At certain points, a tone was played unexpectedly through the headphones, after which the experiment was stopped.

Participants were then asked if they had heard the sound.

When judging colors, only two in ten volunteers missed the tone. But when focusing on the more difficult tasks, eight in ten failed to hear it.

Prof Lavie wrote in the journal Attention, Perception And Psychophysics: "Hearing is often thought to have evolved as an early warning system that does not depend on attention, yet our work shows that if our attention is taken elsewhere, we can be effectively deaf to the world around us."

It is well known that many road accidents are caused by drivers' inattention.

Sounds such as a lorry beeping while reversing, a cyclist's bell or a scooter horn could all be missed by a motorist focusing intently on visual information from a road sign or satellite -navigation map.

一項研究發現，當人們全神貫注看書或做填字遊戲時，他們會暫時聽不到周圍的聲音。

科學家解釋說，當人們集中精神做事時，會對外界一般的聲音充耳不聞。之所以會這樣，是因爲大腦中的視覺細胞和聽覺細胞會爭奪有限的大腦空間。

這在某些時候會產生極其嚴重的後果，比如引發交通事故。這種現象被稱作是“無意失聰”。

倫敦大學學院認知神經學研究所的尼爾利•拉唯教授是這項研究的帶頭人，他說：“‘無意失聰’這種現象在日常生活中很常見。比如，當你全神貫注地盯着一本書或報紙上的一篇文章時，你很有可能會因爲沒聽見火車報站的聲音而坐過站。或者你一邊走路一邊發短信，汽車開來了也聽不見，還要橫穿馬路。”

研究中，100位志願者要在電腦上完成一些試驗項目，包括一些簡單的小遊戲，例如辨別填字遊戲的行列顏色是否相同。有的則屬於比較高難，需要甄別出細微的長度差別。

在志願者答題的過程中，研究人員會突然播放一個聲音，答題過程也會隨之終止。

然後研究人員會詢問志願者是否聽見了這個聲音。

在做色彩辨別時，僅有兩成人沒聽見這個聲音。而在回答更爲困難的問題時，有八成人都沒聽見這個聲音。

拉唯教授在給《注意力、感知力和心理物理學》雜誌撰寫的文章中稱：“人們一般認爲，在人類進化的初級階段，聽覺作爲一種預警能力並不需要注意力。然而我們的研究發現，如果人的注意力被某種東西吸引，他就聽不見周圍世界的聲音。”

衆所周知，許多交通事故都是由於駕駛員注意力不集中造成的。

比如當摩托車駕駛員仔細看路邊的指示牌或電子導航地圖時，他就有可能聽不到卡車、自行車、踏板車朝他開過來的聲音。