Abstract
Introduction. What properties of angles can serve as features for spatially distributed attention? Here we use the centroid paradigm to investigate this question. Methods. Stimuli were clouds of randomly oriented v's with vertices of different angles. In Experiment 1, stimuli comprised eight v's, 4 each with acute and obtuse angles of size that varied randomly both within a trial and across trials. Stimuli were exposed for 200 ms and followed by noise masks. In separate conditions, observers strove to mouse-click the centroid of the v's, giving equal weight to (1) all angles, (2) acute angles (< 90 deg) while ignoring obtuse angles (>90 deg), (3) obtuse angles while ignoring acute angles. Experiments 2 and 3 used v's with only two fixed angle sizes, and participants strove to mouse-click the centroid of a designated one of the two sets. Results. Participants in Experiment 1 gave about 4-5 times more average weight to targets than distracters (we call this measure "Selectivity"). However, for component angles of 67.5 versus 112.5 deg, the most similar target and distracter angles, selectivity was only about 2.5. In Experiment 2, when filtering between just two acute angles (30, 60 deg) participants gave target acute angles about 4 times more weight than distractors. However, when discriminating between 75 versus 105 or between 120 versus 150 deg, selectivity was reduced to less than 2. Conclusions. Angles can be used as a feature in feature based attention. For equal angular differences between targets and distracters, selectivity is greater for small than for large angles.
Meeting abstract presented at VSS 2017