The time-course of covert cuing using spatial frequency targets

Abstract

Purpose: Covert cuing tasks are used to study the deployment of visual attention over space and time. Previously, we reported target spatial frequency (SF) and 3-D object context effects on inhibition of return (IOR) at a long cue-to-target SOA (VSS, 2007). The present study tested for similar SF and object effects with a placeholder paradigm more commonly used in covert cuing tasks. We examined the influences of target SF and context on shifting attention over time by using a range of SOAs with both 2-D and 3-D placeholders. Based on our previous findings, greater IOR was expected for high SF compared to low SF targets at our long SOA. Facilitation was expected at short SOAs for all SFs and both contexts. Method: Placeholders were 2-D outline squares (Exp. 1) and the same outline squares on the front faces of 3-D cubes (Exp. 2). The cue was a brief (50 ms) thickening of the outline square. A Gabor patch target (1, 4, & 12 cpd) followed at one of three SOAs (50, 100 ms, 500 ms) on 80% of the trials. Results: Contrary to our previous results, IOR magnitude was similar for all SFs and contexts at the 500 ms SOA. No inhibition or facilitation occurred for any target or context at 100 ms SOA. Interestingly, significant inhibition was found for 12 cpd targets for both contexts at the 50 ms SOA. Conclusion: Other than the inhibition found for 12 cpd at 50 ms, covert shifts of attention were unaffected by target SF over SOA. The lack of target SF or 3-D object influences with a placeholder paradigm indicates their presence in our previous study was because of the SF specific cues used.