How long should a diary be kept? A diary study of prospective and retrospective memory errors in young and old healthy adults

Memory research has commonly been conducted in the laboratory, and by the use of self-report questionnaires assessing retrospective and prospective memory. Although a diary method can give more accurate insight into everyday memory processes, there are very few diary studies of everyday memory errors. This study added a 28-day diary-recording period to laboratory tests and self-assessment questionnaires. The 28 day period was expected to cover different aspects of life – busier and quieter periods – but initial results showed that surprisingly few memory errors were recorded over a 28 day period, yet participants claimed to have been recording the majority of memory errors experienced during this period. We suspect that participants fatigue over 28 days or start slowly because they feel they have plenty of time, and therefore record fewer errors. A second 7-day diary condition was added and results will compare the number of memory errors committed pro rata over the two diary-keeping periods.