Biomedical subjects

Jeremy M Wolfe

Publications and source records attributed to Jeremy M Wolfe.

4 recordsLinked to original sources

PubMed2003

Changing your mind: on the contributions of top-down and bottom-up guidance in visual search for feature singletons.

Observers, searching for targets among distractor items, guide attention with a mix of top-down information--based on observers' knowledge--and bottom-up information--stimulus-based and largely independent of that knowledge. There are 2 types of top-down guidance: explicit information (e.g., verbal description) and implicit priming by preceding targets (top-down because it implies knowledge of previous searches). Experiments 1 and 2 separate bottom-up and top-down contributions to singleton search. Experiment 3 shows that priming effects are based more strongly on target than on distractor identity. Experiments 4 and 5 show that more difficult search for one type of target (color) can impair search for other types (size, orientation). Experiment 6 shows that priming guides attention and does not just modulate response.

Adolescent↗

PubMed2003

Do intersections serve as basic features in visual search?

The status of 'intersection' as a basic feature in visual search tasks has been controversial. Under some circumstances, a target possessing this attribute (eg a plus) 'pops out' of a display of distractors that lack the attribute (eg Ls). However, those cases may be artifacts of other features such as relative size or number of line terminators. We report two sets of experiments with stimuli intended to control for these factors. Search for the presence or absence of intersections is very inefficient with these stimuli. The results suggest that intersection should not be included among the list of salient features that support efficient search through visual displays.

Adolescent↗

PubMed2002

Segmentation of objects from backgrounds in visual search tasks.

In most visual search experiments in the laboratory, objects are presented on an isolated, blank background. In most real world search tasks, however, the background is continuous and can be complex. In six experiments, we examine the ability of the visual system to separate search items from a background. The results support a view in which objects are separated from backgrounds in a single, preattentive step. This is followed by a limited-capacity search process that selects objects that might be targets for further identification. Identity information regarding the object's status (target or distractor) then accumulates through a limited capacity parallel process. The main effect of background complexity is to slow the accumulation of information in this later recognition stage. It may be that recognition is slowed because background noise causes the preattentive segmentation stage to deliver less effectively segmented objects to later stages. Only when backgrounds become nearly identical to the search objects does the background have the effect of slowing item-by-item selection.

Adult↗

PubMed2002

An unbinding problem? The disintegration of visible, previously attended objects does not attract attention.

In seven experiments, observers searched for a scrambled object among normal objects. The critical comparison was between repeated search in which the same set of stimuli remained present in fixed positions in the display for many (>100) trials and unrepeated conditions in which new stimuli were presented on each trial. In repeated search conditions, observers monitored an essentially stable display for the disruption of a clearly visible object. This is an extension of repeated search experiments in which subjects search a fixed set of items for different targets on each trial (Wolfe, Klempen, & Dahlen, 2000) and can be considered as a form of a "change blindness" task. The unrepeated search was very inefficient, showing that a scrambled object does not "pop-out" among intact objects (or vice versa). Interestingly, the repeated search condition was just as inefficient, as if participants had to search for the scrambled target even after extensive experience with the specific change in the specific scene. The results suggest that the attentional processes involved in searching for a target in a novel scene may be very similar to those used to confirm the presence of a target in a familiar scene.

Attention↗