Abstract
Attention can be directed to two sources of information: to features or to space. In this study, we explored how priming affects these two types of attention. Observers performed a visual search task, in which they indicated whether a pre-specified target was a vowel or a consonant. Four letters served as potential targets. Unbeknownst to the participants, two letters were primed: one appeared in the same color 75% of the time and one appeared at the same location 75% of the time. We assumed that color priming would have a greater influence on feature-based attention and location priming would have a greater influence on space-based attention.
We found that color and location priming shared many features: both forms of priming sped up reaction times to a similar degree and started in a comparable number of trials. Important differences were observed as well. Location priming facilitated all targets appearing at the primed location, whereas color priming was specific to its primed letter. In a second experiment, we tested whether color and location priming are independent by adding a third condition, in which the target appeared in the same color and at the same location 75% of the time. We found that the combination of color and location priming was additive the advantage of ‘both’ equaled the sum of each one. Therefore, feature-based and space-based attention possess different characteristics. Location priming may facilitate processing at an earlier stage, which benefits all targets. By contrast, color priming acts at a later stage where shape and color are integrated. Additional experiments show the mechanisms of this color priming - the situations in which it does and does not generalize.
The authors thank Jo landa Roelofsen for her help with data collection. Funding for this study was provided by the Canadian Institutes of Heath Research and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek.