成年人一只手有多重?


Humans underestimate the weight of their hands by nearly 50%


People perceive their hands to weigh much less than they actually do, underestimating their weight by nearly 50%, according to new research from Birkbeck.

Led by academics Dr Elisa Raffaella Ferre, Reader in Cognitive Neuroscience, and Professor Matthew Longo, Professor of Cognitive Neuroscience, the research team developed a new research method to measure perceived hand weight.

Participants in the study judged whether weights suspended from a wristband were heavier or lighter than perceived hand weight. Hand weight was underestimated on average by 49.4%, an effect the team has called “terrestrial weightlessness”. Moreover, inducing fatigue by hand exercise caused an increase in perceived hand weight.

An object’s weight is usually calculated according to Isaac Newton’s laws and is equal to its mass multiplied by gravitational acceleration, but a person’s perception of their own body weight is constructed by their brain because their central nervous system is not informed by a sensory signal.

Dr Ferre comments: “The sensation of our body’s weight caused by gravity presents an intriguing contrast to the weightlessness experienced in outer space.

“Astronauts are often astonished when the experience of body weight re-emerges on returning to Earth.

“Our findings demonstrate that our everyday experience of body weight – weightedness - can be accurately quantified and it is strongly underestimated.”

Denise Cadete, Birkbeck PhD student and co-author, explains: “We believe this perceptual bias helps to make body movements seem effortless.

“A person’s brain could either encourage or discourage physical exertion by making their body seem light and actions therefore effortless, or heavy and actions thus effortful.

“Phrases such as “my eyelids are getting heavy” which is used to mean that the speaker is sleepy, allude to a commonly experienced relation between their perceived body weight and motivation for action.

“We believe that perceived body weight could be an important component of a system that adapts with evolution to control our levels of behaviour.

“Existing research on body weight has largely focused on the social or medical aspects of how people feel about the overall weight of their body. Surprisingly, no research has investigated the more basic issue of how the brain constructs representations of the weight of individual body parts.”

Professor Longo says: “We investigated, for the first time, how the brain perceives the weight of body parts as spatially extended objects. Our work may have implications for the understanding of disorders of body weight, including anorexia nervosa and obesity.”


生词记录

perceive 感知,察觉,注意到,意识到;认为;看待;视为

Reader 英国大学仅次于教授的)准教授;高级讲师

cognitive 认知的;感知的;认识的

neuroscience 神经系统科学(对神经系统的解剖学、生理学、生物化学和药理学的研究)

wristband 手腕带(绕在手腕上的带子,如手表带)

terrestrial 地球的;与地球有关的;(动物)陆生的,陆栖的;(电视频道)陆地上的,地面上的(与卫星相对而言)

induce 诱发(某种身体反应);引起,导致;催生;引产

mass 大量的;大规模的;大批的

multiply 大幅增加;乘,使相乘

gravitational (尤指地球的)重力的,引力的,地心引力的;严重性;严肃;庄严

acceleration 增速,加快;加速性能

sensory 感觉的;感官的

sensation 轰动;哗然;引起轰动的人(或事物);感觉;知觉;感觉能力;知觉能力

intriguing 非常有趣的;引人入胜的;神秘的

perceptual 感知的;知觉的

exertion 尽力;努力;费力;运用;行使(权威、权力等);施加(影响等)

allude 间接提到;暗指;影射

representation 表现;展现;描绘;描述;陈述;述说;抗议

anorexia nervosa (尤指由于害怕变胖而引起的)厌食(症);食欲缺乏


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