Reading a book triggers an active response in a person's brain, replicating the activity described in the story, a study by Washington University researchers in St. Louis, Mo., indicates.

A brain-imaging study at Washington University tracked brain activity as participants read sections of a story.

What scientists discovered was that parts of the brain associated with certain activities described in the story would light up as the person read those sections.

'This study suggests that readers do mental simulation when they comprehend a story.' —Researcher Jeffery Zacks

For instance, if a character pulled a light cord in the story, the frontal lobe region, which controls grasping motions, would increase in activity.

"There has been good evidence for a while that mental simulation — imagination — can improve performance in sport and other skilled behaviours.

This study suggests that readers do mental simulation when they comprehend a story," Jeffrey Zacks, director of the university's dynamic cognition laboratory, told the Guardian newspaper.

Zacks is also co-author of the study, soon to be published in the journal Psychological Science. The study's lead author is Nicole Speer.

Researchers say those written details about actions and sensation are captured and integrated with personal knowledge from past experiences.

The information is run through mental simulations using brain regions that closely mirror those involved when people perform, imagine or observe real-life activities.

"It could well be that the simulations we perform when reading function like skilled practice. I was reading a cooking magazine last night, and I certainly hope that helps me get better with a whisk," said Zacks.

Participants in the study were shown four stories of fewer than 1,500 words from One Boy's Day, a record of everything one boy did during a day.

"[The story] was collected by a team of observers working in shifts; one team would observe for a little while and then rotate out and write everything they had seen while it was still fresh," said Zacks.

During the study, participants read a computer screen, which displayed one word at a time from the texts.

Researchers coded the texts so they knew when important features of the story were changing and could examine how the brain images altered according to the actions in the story.