Cross-modal, positional, and semantic effects in visual extraction of slope

Abstract

Extracting slopes from arrays of visual features is relevant to perceiving terrains and interpreting graphs. To understand slope perception in a broader context, we investigated the effects of sounds, position, and semantic priming on a visual search task in which observers searched for a specific slope pattern. We used graphs as the stimuli with the purpose of developing methods to improve graph comprehension. Four bar graphs or scatter plots were simultaneously presented in separate quadrants. The task was to press the space bar as quickly as possible if one of the graphs displayed a specific (positive or negative) slope and to refrain from response otherwise. Concurrently presented ascending (or descending) pitch slowed responses to the positive-slope (or negative-slope) targets, indicating crossmodal interference. Positive slopes were detected faster in the upper-right (than upper-left) quadrant whereas negative slopes were detected faster in the upper-left (than upper-right) quadrant, indicating position dependence. Interestingly, this position dependence is consistent with a standard mental number line with negative values extending to the left and positive values extending to the right, though the position effect occurred only in the upper visual field. Finally, positive slopes were detected faster when the search display was immediately preceded by a briefly flashed word "uphill" than "downhill" and vice versa for detecting a negative slope, indicating a semantic priming effect. This priming effect is unlikely due to reminding observers of the target because the target type was blocked (i.e., observers repeatedly searched for either a positive or negative slope), and the semantic priming only affected the perception of scatter plots (not bar graphs). In summary, perception of visual slope is systematically influenced by auditory signals, placement of graphs, and semantic priming, suggesting that slope perception can be influenced by manipulating underlying auditory-visual associations, spatial position, and semantic associations. Meeting abstract presented at VSS 2012