Scientists have come up with a theory for why time flies when you are having fun-- and drags when you are bored.

    Scans have shown that patterns of activity in the brain change depending on how we focus on a task.

    Concentrating on time passing, as we do when bored, will trigger brain activity which will make it seem as though the clock is ticking more slowly.

    The research, by the French Laboratory of Neurobiology and Cognition, is published in the magazine Science.

    In the study, 12 volunteers watched an image while researchers monitored their brain activity using MRI scans.

    Volunteers were given a variety of tasks. In one they were told to concentrate simply on the duration of an image, in another they were asked to focus on the colour, and in a third they were asked to concentrate on both duration and colour.

    The results showed that a network of brain regions was activated when more subjects were paid attention to duration.

    It is thought that if the brain is busy focusing on many aspects of a task, then it has to spread its resources thinly, and pays less heed to time passing.

    Therefore, time passes without us really noticing it, and seems to go quickly.

    However, if the brain is not stimulated in this way, it concentrates its full energies on monitoring the passing of time.

    This may make time seem to drag, but in fact it is probably a more accurate perception of reality.

    Indeed, the researchers found that the more volunteers concentrated on the duration of the images, the more accurate were their estimates of its duration.

    Lead researcher Dr Jennifer Coull said many of the areas of the brain involved in estimating time were the same that played a key role in controlling movement, and preparing for action.

    She said this overlap suggests that the brain may make sense of time as intervals between movements, in much the same way as a musician marks time with his foot, or an athlete anticipates the sound of a starter's pistol.

    科學家們提出理論依據，解釋為什么當你玩得開心的時候，時間總是過得飛快，而當你無聊的時侯，時間卻過得特別慢。

    通過掃描發現，大腦活動的方式隨著我們對事情的關注程度發生變化。

    我們在無聊的時候，往往把注意力集中在時間的流逝上，這樣會使大腦活動產生錯覺，總覺得時鐘似乎走得更慢。

    法國神經生物和認知學實驗室進行的此項研究發表在《科學》雜志上。

    在研究中，當12名志愿者同時看一幅圖像時，研究者們用核磁共振成像掃描儀來監控他們大腦的活動。

    志愿者們被分配了各種不同的任務。一次他們被要求專注于圖象持續的時間，另一次集中觀察圖象的色彩，第三次同時關注圖象持續的時間和色彩。

    結果表明，在觀看圖像的過程中，注意的對象多的話，就會激活大腦區域網絡。

    科學家們認為如果大腦忙于關注一項任務中的多個方面，那么它不得不分散注意力，這樣就不太會注意到時間的流逝。

    所以，我們還沒真正注意到時間，時間就已經過去了，而且似乎過得特別快。

    然而，如果大腦并沒有受到這樣的刺激，它就會把全部精力用來監控時間的流逝。

    這樣就會覺得時間過得特別慢，但是事實上這可能是對現實情況的更準確的認識。

    事實上，研究者們發現，志愿者們越是注意圖像持續的時間，他們對于時間的估計就越準確。

    主任研究員詹尼弗·庫爾博士說，大腦中有許多參與估計時間的區域，同時他們對行為控制和行動準備也起到重要的作用。

    她說這種區域重合說明大腦在活動的間隙可能會注意到時間，在很大程度上就像音樂家用腳來記錄時間、運動員預料發令員的槍聲一樣。