Questionnaires and diaries as research instruments in dream research: Methodological issues.

Dream questionnaires are widely used in dream research to measure dream recall frequency and various aspects of dream life. The present study has investigated the intercorrelation between questionnaire and diary measures. 285 participants completed a dream question-naire and kept a dream diary over a two-week period. Results indicate that keeping a dream diary increased dream recall in low and medium dream recallers but decreased dream recall in high dream recallers. The correlation coefficients between questionnaire items measuring aspects of dream content and diary data were large, except for a more complex scale (realism/bizarreness). In the low recall group, however, considerably lower coefficients were found indicating that recall and sampling processes affect the response to global items measuring dream content. Using the example of testing gender differences, the findings of the present study clearly indicate that the measurement technique affects the results. Whereas sufficient internal consistency and retest reliability have been demon-strated for various dream questionnaires, future research should focus on the aspects of validity by comparing questionnaire data to dream content analysis of at least 20 dreams per person.