Effects of task factors on selection by color in the rapid serial visual presentation (RSVP) task

The Development of Attention to Objects and Scenes: From Object-Biased to Unbiased

Selective attention is the ability to focus on goal-relevant information while filtering out irrelevant information. This work examined the development of selective attention to natural scenes and objects with a rapid serial visual presentation paradigm. Children (N = 69, ages 4-6 years) and adults (N = 80) were asked to attend to either objects or scenes, while ignoring the other type of stimulus. A multinomial processing tree model was used to decompose selective attention into focusing and filtering components. The results suggest that attention is object-biased in children, due to difficulty filtering attention to goal-irrelevant objects, whereas attention in adults is relatively unbiased. The findings suggest important developmental asymmetries in selective attention to scenes and objects.

Distraction by color and its electrophysiological correlates

We used the effects of colored distractors on ERPs to assess the psychophysiological consequences of selection by color. In Experiment 1 participants searched a rapid serial visual presentation (RSVP) sequence for a prespecified target letter that usually appeared in a cued color. ERPs elicited by cued-color distractors were similar to those elicited by targets, indicating relatively complete distractor processing. In Experiment 2 one letter in the RSVP sequence was framed by an irrelevant distractor probe in either the cued color or an uncued color. Such distractor probes elicited a P1, N1, or P2 sequence that depended on their color. In addition, probes presented shortly before the target tended to suppress the ERP components associated with target processing, especially for probes in the cued color. These observed variations in ERPs depending on the distractor's type and its distance from the target help to reveal the time course and mechanisms of selection by color.

Evidence against signal enhancement as a mechanism of direct selection by color

Two of the possible mechanisms that have been put forward to explain precuing effects are signal enhancement and uncertainty reduction. Signal enhancement leads to processing advantages for valid information because the signal at the known input channel is enhanced, whereas uncertainty reduction allows observers to ignore confusing distractor items in a display. Both mechanisms have been reported to be involved in location precuing, but it is still unclear which of these two mechanisms is responsible for color cuing effects. Two experiments are reported in which expectancy for a certain color in a single-item display was created. Targetswere presented briefly and were masked. If color cues produce signal enhancement, then a color cuing effect should result. If color cues only allow uncertainty reduction, however, there should be no color cuing effect because there are no distractors in single-item displays. The results of both experiments favor uncertainty reduction as the mechanism behind color cuing, because no signs of signal enhancement-based cuing effects were observed.