In the audience research field a large experimental study is being carried out by TAM in conjunction with the committee controlling the British television industry's research. One of the aims of the study is to compare aided recall results with coincidental calls and this approach to validation, will be of great interest and require careful evaluation. It is known that many factors may effect the memory function. Apart from the vast body of results from the academic work, it has been shown that the type of aid used may alter the claims given (e.g. the different methods used for attention to press advertisements)| recent research has shown that the type of person attempting the recollection may cause differences in response (e.g. Appel and Blum 1961); the competence of the interviewer regarding the relaxation of the informant may affect the amount of recall (Pascal 1949); the.order of recall may affect the proportion of claims given (e.g. the experience of the I.P.A. Readership Surveys with monthly publications). Nevertheless, none of these factors needs to be assumed to be a general or dominant source of error over all recall studies and for all techniques. The evidence must not be ignored, but with careful experimentation, checks within the data for likely biases, validation with other information where possible, and the use of new forms of aids, it is likely that the value of-aided recall techniques may be considerably extended.