'The arousal from caffeine can prolong the arousal you would have from stressful situation,' which can be detrimental, says Dr. St. Claire. So, she says, people should consider how keyed up they already are feeling before pausing for an additional cup of coffee.

While we seem to need a break from focused work at some point, people can push themselves beyond what they might think they are capable of, according to a study published in Psychological Science in September.

The notion of willpower as a resource that people can strengthen with exercise has gotten recent attention with the publication of 'Willpower: Rediscovering the Greatest Human Strength,' by Roy F. Baumeister and John Tierney.

In the September study, Stanford University researchers showed that people who believe they have an limited" target="_blank" title="a.无限的；过渡的">unlimitedamount of willpower were able to work longer -- without performing worse -- than people who believe that only have only limited willpower.

Both groups reported feeling tired. But researchers subtly suggested in questionnaires to some participants that they had stamina that could be replenished, and this group appeared to overcome the fatigue. A possible reason is that forcing themselves to not think about being tired freed up some additional cognitive resources to work longer on the task at hand, says Veronika Job, a study author now at the University of Zurich.

The message, says Dr. Job, is that you can power through a period of high concentration, such as a final exam, if you believe you have limited" target="_blank" title="a.无限的；过渡的">unlimited willpower.

The researchers are currently studying whether people can make lasting changes to their lives, based on their belief in their willpower. Such research could eventually help people, for example, stick to healthy diets or better regulate their emotions.

'When you have a limited mindset, maybe you'll be able to push yourself through a task, but in the evening you'll think, 'Now I'm done,'' says Dr. Job. Having a sense of increased willpower might make it easier for a person to say no to indulging in candy bars, even after a long day, she says.

Shirley S. Wang

• research [ri´sə:tʃ] n.&vi.调查；探究；研究 (初中英语单词)


• instance [´instəns] n.例子，实例，例证 (初中英语单词)


• mental [´mentl] a.精神的；心理的 (初中英语单词)


• effective [i´fektiv] a.有效的；有力的 (初中英语单词)


• muscle [´mʌsəl] n.肌肉；体力；力量 (初中英语单词)


• working [´wə:kiŋ] a.工人的；劳动的 (初中英语单词)


• concentrate [´kɔnsəntreit] v.聚集；浓缩；全神贯注 (初中英语单词)


• institute [´institju:t] n.学院 vt.建立；设置 (初中英语单词)


• depression [di´preʃən] n.沮丧，抑郁；萧条 (初中英语单词)


• performance [pə´fɔ:məns] n.履行；行为；工作 (初中英语单词)


• actually [´æktʃuəli] ad.事实上；实际上 (初中英语单词)


• journal [´dʒə:nəl] n.日记；日报；杂志 (初中英语单词)


• contrast [´kɔntrɑ:st] n.对比 v.使对比(照) (初中英语单词)


• traffic [´træfik] n.交通，运输 (初中英语单词)


• whereas [weər´æz] conj.鉴于；因此；而 (初中英语单词)


• pressure [´preʃə] n.压榨 vt.对…施压力 (初中英语单词)


• conference [´kɔnfərəns] n.讨论(会)；会谈 (初中英语单词)


• additional [ə´diʃənəl] a.附加的，额外的 (初中英语单词)


• amount [ə´maunt] n.总数；数量 v.合计 (初中英语单词)


• capable [´keipəbəl] a.有能力；能干的 (初中英语单词)


• resource [ri´zɔ:s] n.手段；智谋 (初中英语单词)


• strengthen [´streŋθən, ´strenθən] vt.加强 vi.变强 (初中英语单词)


• overcome [,əuvə´kʌm] vt.战胜，克服 (初中英语单词)


• concentration [,kɔnsən´treiʃən] n.集中，专心 (初中英语单词)


• belief [bi´li:f] n.相信；信仰，信条 (初中英语单词)


• healthy [´helθi] a.健康的 (初中英语单词)


• stroll [strəul] n.&v.漫步；散步；游荡 (高中英语单词)


• fatigue [fə´ti:g] n.&vt.(使)疲劳(劳累) (高中英语单词)


• oregon [´ɔrigən] n.俄勒冈 (高中英语单词)


• necessarily [´nesisərili] ad.必定，必然地 (高中英语单词)


• so-called [´sou ´kɔ:ld] a.所谓的，号称的 (高中英语单词)


• intense [in´tens] a.强烈的；紧张的 (高中英语单词)


• pleasing [´pli:ziŋ] a.使人愉快的；合意的 (高中英语单词)


• landscape [´lændskeip] n.风景；景色；风景画 (高中英语单词)


• potential [pə´tenʃəl] n.&a.潜在的；可能的 (高中英语单词)


• environment [in´vaiərənmənt] n.郊区；周围；条件 (高中英语单词)


• refresh [ri´freʃ] v.使清新；使更新 (高中英语单词)


• translate [trænz´leit, træns-] v.翻译；解释；说明 (高中英语单词)


• access [´ækses] n.接近；通路；进入 (高中英语单词)


• prolong [prə´lɔŋ] vt.延长；拉长；拖延 (高中英语单词)


• publication [,pʌbli´keiʃən] n.发表；公布；发行 (高中英语单词)


• limited [´limitid] a.有限(制)的 (高中英语单词)


• lasting [´lɑ:stiŋ] a.持久的；永远的 (高中英语单词)


• regulate [´regjuleit] vt.管理；调整；规定 (高中英语单词)


• intensely [in´tensli] ad.激烈地；热切地 (英语四级单词)


• beneficial [,beni´fiʃəl] a.有利的，有益的 (英语四级单词)


• psychological [,saikə´lɔdʒikəl] a.心理学(上)的 (英语四级单词)


• trying [´traiiŋ] a.难堪的；费劲的 (英语四级单词)


• unlimited [ʌn´limitid] a.无限的；过渡的 (英语四级单词)


• gotten [´gɔtn] get的过去分词 (英语四级单词)


• eventually [i´ventʃuəli] ad.最后，终于 (英语四级单词)


• involuntary [in´vɔləntəri] a.无意识的；非自愿的 (英语六级单词)


• trigger [´trigə] n.扳机 vt.触发，启动 (英语六级单词)


• lecturer [´lektʃərə] n.演讲者；讲师 (英语六级单词)


• applied [ə´plaid] a.实用的，应用的 (英语六级单词)