Eyes Do Not Have it: A Collinear Salient Line Interferes with Visual Search Responses but Not Eye Movements

Our previous study found that a task-irrelevant salient line impaired visual search when the salient line was composite of collinear bars (Jingling, 2010). In this study, we further investigated whether this inhibition can be observed in eye movements. The search display was a lattice of 21 by 27 bars. The task was to discriminate the orientation of a target, which was presented on one of seven bars in the central of search display. One of the columns of the bars was vertical, thus bars on this line were collinear to each other. The other bars were horizontal, making the collinear line salient. The target was on the bars at salient line by chance. Eight participants were recruited, and eye movements were recorded by EyeLink 1,000 with 250 Hz sampling rate. Results of hand response times replicated our previous findings: Responses were slower for targets on the bars at the salient line than that in the background. However, saccadic duration was not statistically different for these two types of targets. Our data showed that a collinear salient line interferes with key press but not eye movements, suggesting that the inhibitory effect emerged later than sensory information process.