B.1.2.1.2. Priming effects

When assessing the influences of endogenous factors on attentional orienting, another critical methodological issue concerned perceptual priming. Indeed, Maljkovic and Nakayama (1994) showed that perceptual priming ("priming of pop-out") could strongly influence performances in visual search, even up to eight trials after the critical one (for about 30 s). The endogenous cueing has often been manipulated block-wise (e.g. Folk, Remington, & Johnston, 1992; Müller, Heller, & Ziegler, 1995). For instance, a "relevant" feature or dimension could be indicated at the beginning of a block of trials, and then correspond to the target in a large proportion (e.g. 80 %) of this block's trials. With this procedure, however, the relevance of the feature at hand and the occurrence number of a target presenting this feature were confounded, which probably involved strong perceptual priming effects. Consequently, to address endogenous influences, Müller, Reimann, and Krummenacher (2003) recommended using a trial-wise cueing mode.