A picture of a vastly overstretched service, able to work with only half the pupils identified as in need of support, emerges in the first "best value" report produced by the education department.
The council has a child-staff ratio for psychologists of 4,263 to one, the worst in Scotland. There is a yearly turnover of 1,035 cases, 225 for each psychologist. Last autumn staff were working on 522 cases and a further 648 were being held in a "monitoring" status. The number of new referrals has risen by half over five years.
Ken Dutton, the council's principal psychologist, who carried out the review, said the significant and unmet need in the system threatened to "overwhelm" the service. Another three psychologists would be needed to absorb the workload if the council opened a waiting list for pupils currently in the learning support system.
A survey of schools and parents, however, revealed around 80 per cent were satisfied or very satisfied with the psychologists' work. Lack of time to consider cases in depth was the major criticism.
Mr Dutton said: "Headteachers, particularly, commented that they had to wait long periods for assessments and, subsequently, reports. They also commented unfavourably on the norm of working lunches and snatched conversations to conduct business, and having to prioritise cases and work, meaning many needy children were excluded from the system of assessment."
The council says it is cutting the time it takes to process records of need but high caseloads and long delays by the health board contribute to lengthy procedures.