The online encyclopedia Wikipedia has become embroiled in a bitter row with psychologists after a Canadian doctor posted answers to controversial tests on the site.

The Rorschach test is designed to give psychologists a window into the unconscious mind, but many now fear their patients will try to outwit them by memorising the "right" answers.

The test, developed in 1921 by the Swiss psychiatrist Hermann Rorschach, comprises 10 inkblot images, which patients must look at and describe what they see. In some cases, focusing on tiny details around the edges of the images is seen as evidence of obsessive behaviour.

Advocates of the Rorschach test say it can reveal underlying mental issues that patients themselves may not be aware of, but critics dismiss it as out-of-date and it is rarely used in the UK.

The row erupted when hospital doctor James Heilman from Saskatchewan posted all ten inkblot plates on Wikipedia alongside the most common responses given to each. Heilman uploaded the images after becoming frustrated by a debate on the website as to whether a single Rorschach inkblot plate should be taken down. "I just wanted to raise the bar," he said.

The move brought immediate condemnation from psychologists who signed on to complain that making the tests public renders them useless. "Making images available on the internet will make it obsolete and we will have lost a helpful tool," said one.

Psychologists familiar with the Rorschach test say it is most valuable when patients describe the first thing that comes into their head on seeing the inkblots. Publishing the images and common reactions on the internet means patients are more likely to be familiar with the test and give considered, less helpful answers.

Mike Drayton, a consultant clinical psychologist at Opus Psychology in Birmingham, said: "It completely compromises the validity of the test."

The Rorschach inkblots have been published before, in the 1983 book Big Secrets, by William Poundstone, which gives details of how the test is administered.

Tony Black, who used the Rorschach test on patients held at Broadmoor, the high-security psychiatric hospital in Berkshire, said while he was sceptical about the test, it was a mistake to publish the images and answers on the internet.