Attention and eye movement control: Interaction of top -down and bottom -up information
Many studies show that bottom-up and top-down information interactively control attentional deployment. This study explores how these two factors are integrated when controlling attention and eye movements. In this study, attention was affected by top-down factors (informative location cues, strategies) and by a bottom-up factor (an orientation singleton), with the intensity of each manipulated systematically. Results of Experiment 1 showed that one top-down factor (previous knowledge about the target location) can control attention independently from the bottom-up factor. This result raises some difficulties for those models that predict competition between top-down and bottom-up factors to control attention. The study implies separation between the pathways for top-down attention control and bottom-up attention control. This pattern is consistent with recent neuroscience findings, which show that different brain regions are involved in top-down and bottom-up attention control.
Strategies were manipulated between Experiment 1 and Experiment 2. In Experiment 1, participants were encouraged to employ a singleton detection mode; in Experiment 2, participants could not employ a singleton detection mode. Results showed that the singleton could capture attention in Experiment 1; however, only the most salient singletons could capture attention in Experiment 2. This result is only partially consistent with the idea that a singleton could capture attention only when participants employ a singleton detection mode. Singletons with some specific properties could apparently capture attention even when participants could not employ singleton detection mode.
Experiment 3 showed that eye movements are also controlled by the interaction of the top-down factors and the bottom-up factors. First saccades went to the singleton location more often if participants employed singleton detection mode than if they used a different strategy. First saccades also went to the singleton location more often when the informativeness of the cue decreased, and when the orientation of the singleton increased. Eye movement control differed from covert attention control in that it showed competition between top-down and bottom-up factors. This difference in overt and covert attentional control probably arises because covert attention can be simultaneously split across multiple locations, while the eyes can only be directed to a single location at any one time.
Cognition & reasoning