Biomedical subjects

Matthew S Peterson

Publications and source records attributed to Matthew S Peterson.

3 recordsLinked to original sources

PubMed2003

How much memory does oculomotor search have?

Research has demonstrated that oculomotor visual search is guided by memory for which items or locations within a display have already been inspected. In the study reported here, we used a gaze-contingent search paradigm to examine properties of this memory. Data revealed a memory buffer for search history of three to four items. This buffer was effected in part by a space-based trace attached to a location independently of whether the object that had been seen at that position remained visible, and was subject to interference from other stimuli seen in the course of a trial.

Adult↗

PubMed2003

Contingent visual marking by transients.

Preview search is a phenomenon in which a set of new items can be searched with seemingly no interference from items already present in the display. The preview effect has been shown to occur only when the presentation of the new items is accompanied by a luminance change (Donk & Theeuwes, 2001). In a series of experiments, we extend the type of transients that can lead to a preview benefit to offsets and motion, and confirm Donk and Theeuwes's finding that equiluminant color changes do not lead to a preview effect. Like Donk and Theeuwes, we find that preview search does not occur when only the old items undergo a transient change, suggesting that the processes responsible for preview search are triggered when the new items undergo a change detectable by the magnocellular system. In addition, we find that irrelevant transients interfere with preview search only when they match the current attentional set (e.g., luminance change or motion). Results suggest that preview search is not the automatic capture of attention by transients, but rather is contingent on top-down control settings.

Adult↗

PubMed2002

Overt and covert object-based attention.

To examine the role of perceptual object representations in the control of eye movements and attention, a pair of experiments adapted the object-cuing paradigm of Egly, Driver, and Rafal (1994) to require eye movements. Displays were pairs of adjacent rectangles, each containing two characters. Observers were asked to make a speeded judgment of a target character's orientation, and a cue was provided prior to target/distractor onset to indicate the target's likely location. Gaze-contingent presentation of target and distractors was used to demand overt scanning of displays. Eye movements during task performance evinced two forms of object-based effects. First, saccades following fixation on an invalidly cued item were more likely to be made within the cued rectangle than between rectangles. Second, saccades within the cued rectangle were preceded by shorter dwell times than saccades between rectangles. Extrafoveal processing of stimuli within the cued rectangle, however, was not facilitated, suggesting that covert attention was not allocated more densely within the cued than within the uncued object.

Adult↗