Abstract
The visual scenes we search every day are far more complex than typical search paradigms. Recent research has addressed this by examining the role target-background similarity plays in search. Previous studies of target-background similarity (camouflage) have utilized a paradigm that includes a complex background created from tiled square segments of the target object (Boot, Neider, & Kramer, 2009). These studies have found large improvements with training and transfer to novel camouflage stimuli. Interestingly, participants were biased to look at salient non-target objects rather than the target-similar background. Is this a true object bias? An alternative explanation is that the regular, crystalline structure of the background encouraged participants to fixate breaks in this pattern (i.e., salient objects). It is possible the high degree of transfer observed was a result of this strategy. We developed a modified paradigm to address these issues. Backgrounds were created through the random placement of geometric cut-outs of the target object to remove target location cues provided by breaks in a patterned background. Error rates and reaction times were increased compared to search performance with structured backgrounds, suggesting structure was important in previous studies. Fixations on the randomized backgrounds were significantly greater, suggesting that previous evidence of an object bias in camouflage search may have been attributable to search strategies developed specifically for structured backgrounds. An additional training study examined search improvement and transfer in this more difficult task. Participants were trained to find camouflaged targets embedded within structured or unstructured randomized backgrounds. After four sessions of training, all participants searched for novel targets embedded within unstructured backgrounds. Preliminary results suggest that transfer of training to novel stimuli is much more limited when participants have to search unstructured camouflage environments. These results have theoretical implications for object-based conceptions of attention and may have important applied implications as well.