4Further Reading: Better Meetings. Open University Press
Starting early: an extra commandment? Some readers will be familiar with the notion that, in order for greatest success of intervention to be achieved, an early start in life is recommended. We too agree that, where possible, intervention should begin early. However, we would like to add a note of caution to an unqualified acceptance of a particular form of this notion of early intervention. For the suggestion is often made that intervention should begin within certain time limits. Usually, these time limits occur at early ages. The term 'critical periods' has been designated for these narrow time constraints. What would acceptance of fixed 'critical periods' mean for us in practice

In practical terms, when a non- specialist hears that "to be effective, work should really have started before the child was 18 months", and their learner is now 8 years old, a feeling of abandonment may follow. Because it is 'too late' should be or she forget about trying that strategy and get on with other things1 We would take the view that if one adopts this argument, the self-fulfilling nature of the proposition will emerge. Better to try and not succeed, than never to have tried at all.

Another practical problem with this view is which particular age one takes to be covered by a critical period. Should it be the child's chronological age, or his conceptual age1 With high-tech equipped intensive care units, there may nowadays be a four month gap between the two ages. Also most of the evidence on critical periods for vision covers the single impairment of vision. Perhaps multiple disability extends rather than reduces the sup posed critical period.

Evidence that would allow us to decide one way or the other as to the validity of the critical period argument is simply not good enough. Note, how ever, that this is not the same as saying that if you get the chance to begin intervention early, then you might as well wait. It is merely to argue that if you meet a learner who has gone beyond the 'critical period', you should still try.

There are also emotive consequences of following the critical period notion without question. These stem from the practical consequences we have summarised above. One difficulty would be that we might end up saying to parents that there is no point in trying to improve the child's use of residual vision.

There is though a related difficulty in wholesale rejection of the idea of critical periods. Parents and professionals who have seen change taking place often assume that this process is set to continue at the same rate. If we see over one year that there has been X percent of improvement, this does not, however, necessarily mean that over three years, there will be 3 times X per cent of change. It can be difficult to have this apparent pessimism accepted. It does not stop us trying, serving instead as a cautionary note.

Need for evaluation

: Cliff Cunningham and his re search group followed up a large group of children with Down syndrome who received a variety of forms of home visiting. They were interested in looking at three variables:

age of commencement of home visiting - was it better to start early?

frequency of visits - did more visits give more benefit?

the nature of the intervention - some children were observed only, some were given more formal visits. Other families were given written instructions. Did more intense work pay off?

Their results were surprising to any who express the view that early intervention is a "good thing". There was no evidence that age at commencement of intervention in the first year was associated with improvements in development at late ages (aside from in one specific feature). The main effects of age of commencement of visiting were in parental adjustment. and counselling aspects. The second set of results showed no evidence to support the notion that greater frequency of visiting led to improvements in development. Likewise, intensity of visiting showed no effect: it did not matter the type of work carried out during visits.

The results of this study teach a salutary lesson. The effects of our intervention are not always what we would like to believe them to be. Evaluation helps keep a perspective on our work. (See Aitken 1988, Cunningham, 1980)