Abstract
Negative priming (NP) is a deficit in processing a stimulus that has been previously ignored; object-substitution masking (OSM) is a deficit in processing a stimulus that is followed closely by a nearby stimulus. Explanations based on selective attention have been proposed for both phenomena. The current experiment combined NP and OSM to create a situation where OSM could potentially be strengthened or weakened via NP effects. The experiment closely resembled that of Enns and DiLollo (1997), in which four dots, presented around one of a number of modified-diamond potential targets, trail in the display after target offset. Enns and DiLollo (1997) found a strong effect of number of potential targets and of target location, indicating a role for visual attention. Each trial of the present experiment presented three modified-diamond potential targets, each randomly selected to be red or green, followed by four dots, all red or all green, which appeared surrounding one of the potential target locations. Observers had to indicate whether the target diamond indicated by the four dots had its left or right corner removed. We expected that when a trial involving a red (green) mask (which observers would presumably try to ignore) was followed by a trial involving a red (green) target, NP would slow processing and thus reduce accuracy on this second trial. However, to date, no reliable effect of NP has been found in our study. We suspect that because colour was incidental to the shape-discrimination task, it may not have been encoded in a way conducive to NP. Thus current studies are investigating the possibility of NP for shape in the context of OSM.
NSERC