By Justin Parkinson
BBC News education reporter
Computers are being used to mark American university students' essays in a project which could radically alter the teaching role of academics.
Students can get instant essay feedback
Qualrus, a program developed at the University of Missouri, offers instant feedback on even complex subjects.
It picks up word patterns, from which it can tell whether students' arguments are sound, and gives the essay a score.
Its developer, Professor Edward Brent, says Qualrus will save staff hundreds of hours of marking time.
He told the BBC News website: "The program uses several different intelligence strategies.
"It compares the information with that offered by all previous candidates and the information entered previously by the course tutor."
Students taking Prof Brent's sociology course submit their draft essays online and receive detailed feedback within a couple of seconds.
It gives a numerical score based on the weight instructors place on different parts of the assignment.
Qualrus is not designed to replace the academics' marking, but to ensure undergraduates are thinking along the right lines before handing in their final work.
Prof Brent said: "We rarely disagree with what the program has said.
"But we don't want to create just a template which operates to the detriment of student originality. We try to make it flexible.
"It makes our job more interesting because we don't have to deal so much with the facts and can concentrate more on thinking."
The half-year sociology course at the University of Missouri usually attracts between 70 and 200 students, meaning a lot of essay-marking.
The software system was adopted after a vote by undergraduates.
They were asked to choose between marked essays or multiple-choice questions - less time-consuming for academics - as the main form of assessment.
Prof Brent said: "Students were two-to-one in favour of essays. They would far rather write longer pieces of work and this enables them to get better feedback.
"Now they can revise their work as many times as they like before submitting their final effort."
Several projects have looked at marking work electronically.
High schools in Indiana began using a program called E-rater last year to grade English essays.
In England, the exam board Edexcel uses e-mail to send answers to complex questions to teachers marking at home.
Qualrus was developed with a $100,000 (£53,500) grant from the National Science Foundation.