Karla K. Evans, Todd S. Horowitz, and Jeremy M. Wolfe
Humans can sort visual information into categories instantaneously. But does the visual system assess a single category at a time or determine multiple categories all at once? Researchers asked volunteers to view pictures and assign them to categories. They found that individuals could accumulate information about multiple categories in parallel, and if participants were cued to focus on one category, it could affect their accuracy in detecting another category. Yet when participants were cued to focus on two categories, they were able to detect both categories equally. These findings indicate that people are able to process multiple categories of visual information at the same time, but they may perceive inaccurate information if their focus is biased toward a particular category.
Serap Yigit-Elliott, John Palmer, and Cathleen M. Moore
Two mechanisms can help people filter a constant stream of sensory information: blocking, in which unattended stimuli are not processed, and attenuation, in which the intensity of unattended stimuli is reduced but the stimuli can still be processed. To better characterize these mechanisms, two experiments in which observers were asked to determine the contrast of a target object (e.g., was the object lighter or darker than the background) were conducted. Observers were shown either targets and irrelevant objects (spatial filtering condition) or targets that changed location over time (spatial monitoring condition). Eye position and other measurements were collected, and the results suggest spatial filtering is associated with blocking and spatial monitoring is associated with attenuation.
Guido Orgs, Sven Bestmann, Friederike Schuur, and Patrick Haggard
Previous studies have suggested that when people view a series of still photographs in which a person appears to be moving, they perceive time the same way they would when watching the actual motion. To test whether manipulating the order of the movement images would affect perception of time, participants were asked to judge how long a rectangle was displayed around three pictures of a dancer in the initial, intermediate, and final positions of a single movement. Participants were also asked to judge how fast the subject in the pictures appeared to be moving. The participants who viewed picture sequences with a longer movement path were more likely to state that the rectangle appeared for a short time, and they also perceived that the dancer moved at a higher velocity. These results indicate a possible top-down mechanism for perception of biological motion.