Limited attention: the constraint underlying search image

Recent models of predator search behavior integrate proximateneurobiological constraints with ultimate economic considerations.These models are based on two assumptions, which we have criticallyexamined in experiments with blue jays searching for artificialprey images presented on a computer monitor. We found, first,that when jays had to switch between searching for two distinctprey types, they showed no reduction in detection rates comparedto no-switching to no-switching conditions, and second, thatwhen jays divided attention between searching for two prey typesat the same time, they had lower detection rates than whenthey focused attention on one prey type at a time. Our resultssuggest that limited attention strongly affects predator searchpatterns and diet choice, including the ubiquitous tendencyto form search images.