Scottish deaf pupils are being disadvantaged during exams by substandard signing and a lack of subject expertise among communicators, it was claimed this week.
A new study has found deaf candidates who sit Scottish Qualifications Authority examinations using a sign communicator have "very different exam experiences and levels of access".
Eileen Burns, Inverclyde Council's manager of deaf education, calls in her master's thesis for the SQA to provide more detailed guidance for centres and mandatory training for communicators.
Less than half (44 per cent) of the communicators she surveyed had the minimum level of British Sign Language qualification recommended by the National Deaf Children's Society - the signature level 3 BSL qualification.
This was also the minimum qualification for communicators recommended by Mary Brennan, the senior lecturer in deaf education at the University of Edinburgh, whose report in 2000 played an important role in persuading the SQA to allow deaf children to have exams communicated to them in sign language as opposed to English.
English, even in its written form, is a second language for many deaf children and they can find it hard to learn because they have never heard it spoken.
Mrs Burns, who presented her findings at the Scottish Sensory Centre conference this week, said: "If communicators are qualified to level 3 (in BSL) you can start to call them fluent."
The communicators' subject knowledge was also vital for successful translation of exam questions, continued Mrs Burns.
"How can you give a proper interpretation of a chemistry exam if you don't understand the chemistry?" she asked.
The report called for interpreters to have more time to prepare themselves for signing a paper before an exam. Half of those surveyed claimed the hour they currently have under the SQA's special exam arrangements was not long enough.
As well as being disadvantaged, deaf candidates could sometimes be unfairly advantaged, added the report entitled How Can We Improve Access to SQA Exams for Signing Deaf Candidates? The sign for radius, for instance, was so visual it could give the answer away.
Finger-spelling was used by some interpreters to get round the problem but this tested deaf candidates' English, not their subject knowledge, argued Mrs Burns.
She called for deaf educationalists who were subject specialists to become involved in the setting of SQA exams to eliminate the practice of finger- spelling technical terms and to allow deaf candidates to benefit from more visual exam papers.
Digital examinations featuring videos of specialist interpreters signing questions would solve many of the problems being experienced by deaf candidates, Mrs Burns concluded. They would also lead to a more standardised presentation of papers, with candidates able to repeat questions as often as necessary, free from embarrassment.
The SQA said that its overarching aim was always to ensure no one was disadvantaged.