Colour priming modulates the attentional boost effect.

The attentional boost effect (ABE) refers to enhanced memory encoding during dual tasks. This study examined whether colour priming influences passive attentional capture and modulates ABE strength. Participants completed an encoding-recognition task across three priming conditions (red, green, and yellow). Each condition comprised four parts: the priming, encoding, wash-out, and recognition phases. During the priming phase, participants passively viewed a series of images predominantly associated with a specific colour. In the encoding phase, participants engaged in a dual task that required the detection of red target signals (while ignoring green distractor signals) and simultaneous memorisation of background words. Recognition performance was then assessed using an old-new classification task. Results revealed significant differences in ABE strength across the three priming conditions. Red priming (a colour congruent to the target signals) produced the strongest memory enhancement, suggesting that the priming facilitated attentional capture. By contrast, green priming (a colour incongruent to the target signals) reduced the ABE strength in comparison to the red and yellow priming conditions, which was potentially caused by interference associated with an attentional shift towards the distractors. A reversed colour assignment in a control experiment (i.e. green for target signals and red for distractor signals) produced a comparable pattern of effects to those observed in the main experiment, with the green (colour-congruent) priming condition yielding the greatest ABE strength. These findings indicate that colour priming can strengthen passive attentional engagement and enhance memory encoding in tasks involving divided attention, highlighting the importance of feature congruence in modulating ABE.