Searching for two categories of target in dynamic visual displays impairs monitoring ability

Target onsets in dynamically changing displays can be predicted when contingencies exist between different stimulus states over time. In the present study, we examined predictive monitoring when participants searched dynamically changing displays of numbers and colored squares for a color target, a number target, or both. Stimuli were presented in both contiguous and discrete spatial configurations. Response time (RT) and accuracy were recorded, and evidence of predictive monitoring was assessed via first fixations and refixations of target-predictive stimuli. RTs to target onsets and evidence of predictive monitoring were reduced in dual-target, relative to single-target, conditions. Further, predictive monitoring did not speed RTs but was influenced by display configuration. In particular, discrete displays impaired monitoring for number targets in the dual-target condition. Implications exist for real-world visual tasks involving multiple target categories and for visual display design.