Giving students a biscuit makes them more likely to rate their teacher highly and be satisfied with the course they are studying, a research study suggests.

The study, reported in The Times, found that in classes where biscuits were offered, the teacher rating was about 4 per cent higher than in classes without biscuits, while the course material was seen as about 20 per cent better.

The paper’s senior author, Manuel Wenk, from the University Hospital Münster, in Germany, said he was inspired by a colleague’s experiences.

“One of our teachers always gives the same talk, in summer and winter,” he said. “The only difference is when he did it in December he always brought chocolate. When we compared, there was a much better evaluation in winter. We were thinking, ‘Could it be the chocolates?’”

‘A popularity contest’

The study, due to be published in the journal Medical Education, put 118 undergraduate medical students into 20 groups for lessons over the course of a term.

All of the groups had the same lectures and course material, but in half there was also an “intervention” in the form of “500g chocolate cookies”.

Measures of student satisfaction are a controversial area, with critics saying they are not an objective test of teaching ability but more of a popularity contest in which, for example, attractive teachers and those who give out higher marks may be rated better.

Dr Wenk was reported as saying that his university superiors did not yet know about the study, but that he was looking forward to telling them about it.

“I’m sure they will think it is funny - everyone relates to cookies,” he said. “But if you use the results of these evaluations to make far-reaching decisions, the fun part disappears.”