Abstract
Subsequent search miss (SSM) errors, wherein observers are prone to miss a second target if a first was already detected, are well documented in academic radiology and cognitive psychology. This phenomenon (originally called satisfaction of search) has critical implications as radiologists are more likely to miss an abnormality if a prior abnormality was detected. Cognitive psychologists have replicated the SSM effect with simplified and randomly-generated search displays in attempts to inform its underlying cause(s). Within these experiments, a SSM effect is typically taken as the difference between the hit rate for a second target on dual-target trials and the hit rate on single-target trials. However, this approach may artifactually inflate estimates of SSM errors. In dual-target displays, the easier target is likely to be found first, implying that the second target is more difficult. Consequently, second-target data are more likely to come from the harder portion of the distribution of trials, whereas single-target data include the full range of target difficulty. The current study demonstrates that this participant-driven circularity inflates empirical estimates of the SSM effect, but nowhere near enough to explain the entire effect. Further, the circularity can be avoided with matched single and dual-target displays, so that whichever target is detected second, a matched single-target trial is available for comparison. This “matched-display” design, already widely used in radiology, equates many confounds that make a target harder to find (e.g., clutter). While previous SSM studies in cognitive psychology are still informative, they likely overestimated the absolute SSM effect. This study argues for a course correction to unbiased methods and designs, which will ultimately improve the sensitivity of SSM experiments by removing an artifactual inflation. Moreover, it is important to consider other psychology paradigms that might include similar participant-driven circularities as this issue is not isolated to SSM studies.
Acknowledgement: Postdoctoral Ford Foundation Fellowship