Comparing target detection errors in visual search and manually-assisted search

Search and concealment strategies in the spatiotemporal domain

Although visual search studies have primarily focused on search behavior, concealment behavior is also important in the real world. However, previous studies in this regard are limited in that their findings about search and concealment strategies are restricted to the spatial (two-dimensional) domain. Thus, this study evaluated strategies during three-dimensional and temporal (i.e., spatiotemporal) search and concealment to determine whether participants would indicate where they would hide or find a target in a temporal sequence of items. The items were stacked in an upward (Experiments 1-3) or downward (Experiment 4) direction and three factors were manipulated: scenario (hide vs. seek), partner type (friend vs. foe), and oddball (unique item in the sequence; present vs. absent). Participants in both the hide and seek scenarios frequently selected the oddball for friends but not foes, which suggests that they applied common strategies because the oddball automatically attracts attention and can be readily discovered by friends. Additionally, a principle unique to the spatiotemporal domain was revealed, i.e., when the oddball was absent, participants in both scenarios frequently selected the topmost item of the stacked layer for friends, regardless of temporal order, whereas they selected the first item in the sequence for foes, regardless of the stacked direction. These principles were not affected by visual masking or number of items in the sequence. Taken together, these results suggest that finding and hiding positions in the spatiotemporal domain rely on the presence of salient items and physical accessibility or temporal remoteness, according to partner type.

What do we know about volumetric medical image interpretation?: a review of the basic science and medical image perception literatures

Interpretation of volumetric medical images represents a rapidly growing proportion of the workload in radiology. However, relatively little is known about the strategies that best guide search behavior when looking for abnormalities in volumetric images. Although there is extensive literature on two-dimensional medical image perception, it is an open question whether the conclusions drawn from these images can be generalized to volumetric images. Importantly, volumetric images have distinct characteristics (e.g., scrolling through depth, smooth-pursuit eye-movements, motion onset cues, etc.) that should be considered in future research. In this manuscript, we will review the literature on medical image perception and discuss relevant findings from basic science that can be used to generate predictions about expertise in volumetric image interpretation. By better understanding search through volumetric images, we may be able to identify common sources of error, characterize the optimal strategies for searching through depth, or develop new training and assessment techniques for radiology residents.

Eye and head movements are complementary in visual selection

In the natural environment, visual selection is accomplished by a system of nested effectors, moving the head and body within space and the eyes within the visual field. However, it is not yet known if the principles of selection for these different effectors are the same or different. We used a novel gaze-contingent display in which an asymmetric window of visibility (a horizontal or vertical slot) was yoked to either head or eye position. Participants showed highly systematic changes in behaviour, revealing clear differences in the principles underlying selection by eye and head. Eye movements were more likely to move in the direction of visible information-horizontally when viewing with a horizontal slot, and vertically with a vertical slot. Head movements showed the opposite and complementary pattern, moving to reveal new information (e.g. vertically with a horizontal slot and vice versa). These results are consistent with a nested system in which the head favours exploration of unknown regions, while the eye exploits what can be seen with finer-scale saccades.