Adults can ignore old and prioritize newly arriving visual stimuli, enabling optimal goal-directed search (visual marking; Watson & Humphreys, 1997). However, the ability to use time of appearance to enhance visual search is currently absent in work on attentional development in children. Experiment 1 examined children's (6-, 8-, and 12-year-olds) and adults' ability to ignore old and prioritize new stimuli and the relationship of this ability to executive functions. Experiment 2 examined whether the components involved in ignoring old items (encoding and maintenance) change across age, by presenting old stimuli for relatively short (500 ms), medium (1,000 ms) or long (1,500 ms) durations. On average, all age groups could ignore old items presented for 1,000 ms to some degree, however 25% of 6-year-olds were not able to prioritize new items effectively. No relationship was observed between the development of this ability and measures of executive function. On average, all age groups could ignore old items presented for short durations, however, 6-year-olds had difficulty ignoring stimuli presented for long durations. The findings suggest that the ability to ignore old items in order to prioritize search through new information is relatively weak in 6-year-olds, especially when ignoring items over longer durations. Furthermore, the findings indicate that the encoding and maintenance components involved in prioritizing new items might follow distinct developmental trajectories.