Recent research has demonstrated that what observers attend to at a given time affects how their attention is deployed in the few moments that follow. When an observer searches for a discrepant target, repetition of the target feature from the previous trial speeds search, an effect known as priming of pop-out (PoP). Previous PoP studies have relied exclusively on spatial search tasks. Here, using a rapid serial visual presentation task, we show that PoP also occurs when temporal uncertainty makes search necessary, and that when spatial and temporal search trials are interleaved, the PoP effect transfers from one task to the other. The results suggest that common mechanisms of target-feature activation and distractor-feature inhibition underlie spatial and temporal visual search. They elucidate the role of PoP in visual search by showing that it speeds engagement of attention to the selected target, rather than earlier stages involving target localization and attention focusing.