This study examines the effects of a timeline tool that was employed as a visual recall aid for respondents in a standardised telephone survey. The timeline was tested in a split-ballot field experiment on the purchase behaviour of clients of opticians, the recall period being approximately 7 years. Optician database information was used as gold standard for recall accuracy. Respondents' retrospective reports about purchases of pairs of glasses were compared to the records regarding the price and the date of the most recent purchase and the number of purchases. In most cases, the timeline enhanced recall accuracy. Furthermore, it appeared to be especially helpful when the respondent's recall task was relatively difficult. The advantages and limitations of employing the timeline are discussed in relationship to the supposed underlying cognitive mechanisms. Copyright © 2007 John Wiley & Sons, Ltd.