Biomedical subjects

B J Scholl

Publications and source records attributed to B J Scholl.

5 recordsLinked to original sources

PubMed2001

Objects and attention: the state of the art.

What are the units of attention? In addition to standard models holding that attention can select spatial regions and visual features, recent work suggests that in some cases attention can directly select discrete objects. This paper reviews the state of the art with regard to such 'object-based' attention, and explores how objects of attention relate to locations, reference frames, perceptual groups, surfaces, parts, and features. Also discussed are the dynamic aspects of objecthood, including the question of how attended objects are individuated in time, and the possibility of attending to simple dynamic motions and events. The final sections of this review generalize these issues beyond vision science, to other modalities and fields such as auditory objects of attention and the infant's 'object concept'.

Attention↗

PubMed2001

What is a visual object? Evidence from target merging in multiple object tracking.

The notion that visual attention can operate over visual objects in addition to spatial locations has recently received much empirical support, but there has been relatively little empirical consideration of what can count as an 'object' in the first place. We have investigated this question in the context of the multiple object tracking paradigm, in which subjects must track a number of independently and unpredictably moving identical items in a field of identical distractors. What types of feature clusters can be tracked in this manner? In other words, what counts as an 'object' in this task? We investigated this question with a technique we call target merging: we alter tracking displays so that distinct target and distractor locations appear perceptually to be parts of the same object by merging pairs of items (one target with one distractor) in various ways - for example, by connecting item locations with a simple line segment, by drawing the convex hull of the two items, and so forth. The data show that target merging makes the tracking task far more difficult to varying degrees depending on exactly how the items are merged. The effect is perceptually salient, involving in some conditions a total destruction of subjects' capacity to track multiple items. These studies provide strong evidence for the object-based nature of tracking, confirming that in some contexts attention must be allocated to objects rather than arbitrary collections of features. In addition, the results begin to reveal the types of spatially organized scene components that can be independently attended as a function of properties such as connectedness, part structure, and other types of perceptual grouping.

Analysis of Variance↗

PubMed2001

How not to be seen: the contribution of similarity and selective ignoring to sustained inattentional blindness.

When people attend to objects or events in a visual display, they often fail to notice an additional, unexpected, but fully visible object or event in the same display. This phenomenon is now known as inattentional blindness. We present a new approach to the study of sustained inattentional blindness for dynamic events in order to explore the roles of similarity, distinctiveness, and attentional set in the detection of unexpected objects. In Experiment 1, we found that the similarity of an unexpected object to other objects in the display influences attentional capture: The more similar an unexpected object is to the attended items, and the greater its differencefrom the ignored items, the more likely it is that people will notice it. Experiment 2 explored whether this effect of similarity is driven by selective ignoring of irrelevant items or by selective focusing on attended items. The results of Experiment 3 suggest that the distinctiveness of the unexpected object alone cannot entirely account for the similarity effects found in the first two experiments; when attending to black items or white items in a dynamic display, nearly 30% of observers failed to notice a bright red cross move across the display, even though it had a unique color, luminance, shape, and motion trajectory and was visible for 5s. Together, the results suggest that inattentional blindness for ongoing dynamic events depends both on the similarity of the unexpected object to the other objects in the display and on the observer's attentional set.

Adult↗

PubMed1999

Tracking multiple items through occlusion: clues to visual objecthood.

In three experiments, subjects attempted to track multiple items as they moved independently and unpredictably about a display. Performance was not impaired when the items were briefly (but completely) occluded at various times during their motion, suggesting that occlusion is taken into account when computing enduring perceptual objecthood. Unimpaired performance required the presence of accretion and deletion cues along fixed contours at the occluding boundaries. Performance was impaired when items were present on the visual field at the same times and to the same degrees as in the occlusion conditions, but disappeared and reappeared in ways which did not implicate the presence of occluding surfaces (e.g., by imploding and exploding into and out of existence instead of accreting and deleting along a fixed contour). Unimpaired performance did not require visible occluders (i.e., Michotte's tunnel effect) or globally consistent occluder positions. We discuss implications of these results for theories of objecthood in visual attention.

Adult↗

PubMedDate not supplied

Minds, modules, and meta-analysis.

Wellman and colleagues' meta-analysis of performance on the false-belief task is methodologically useful, but it does not lead to any theoretical progress concerning the nature of the mechanisms that underlie the existence and development of "theory of mind." In particular, the results of this meta-analysis are perfectly compatible with "early competence" accounts that posit a specific, innate, and possibly modular basis for theory of mind. The arguments presented by Wellman and colleagues against such views stem not from their meta-analytic data, but from mistaken assumptions regarding the requirements of such theories (e.g., that there exist manipulations that improve performance only, or to a greater degree, in young children). Contrary to what Wellman and colleagues claim, their meta-analysis, while consistent with conceptual change, does not lend any new support for such theories.

Child↗