Abstract
Introduction. Success in filtering irrelevant information depends on the relative salience of attended and unattended features, and the attentive demands of the task (Lavie, 2004). In difficult tasks, high salience features are robust against the interfering potential of irrelevant distractors, even when the distractors are also highly salient (Lu and Han, 2009.). When targeted features have low salience, sensitivity is more susceptible to the influence of distractors. In this experiment, we measure if attention to features of a dynamic sequence (either relative timing and contrast) is modulated by the second unattended feature. Methods. Subjects viewed a pair of discs (4 degrees eccentric) flickering aperiodically (with an average flicker rate of 3-15Hz) between black and white for 1000 ms. By using aperiodic sequences, we were able to manipulate the color contrast and phase synchrony relationships independently (between completely uncorrelated and correlated, in 25% increments). Subjects were asked to attend to and judge the simultaneity of the discs based either on 1) color contrast, or 2) onset/offset timing (phase). Results. Subjects' rating of the perceived simultaneity of color contrast tracked closely with the veridical color synchrony between the discs (e.g. when the discs are 75% in sync, subjects judge the discs to be similar 75% of the time). This was true regardless of flicker rate (6-15Hz) and phase synchrony. Ratings of temporal phase (relative timing of onsets and offsets) were not correlated with the actual phase relationships of the disks, regardless of flicker rate (2.5-9 Hz). Conclusions. Subjects can successfully attend to the contrast of the flickering discs, without interference from the relative timing and flicker rate. Because contrast is a highly salient feature, subjects may be unable to disengage attention from the color patterns of the discs in order to determine temporal phase relationship.
Meeting abstract presented at VSS 2014