Abstract
Purpose: Biological motion has been considered a special type of motion. However, few studies have explicitly taken into account that biological motion consists of structured motion when comparing biological motion to non-biological motion. Method: Across experiments, five target motions of three different sizes were used: biological, unstructured translational, unstructured rotational, structured translational, and structured rotational. Unstructured motions were created by randomly plotting target dots within the target area and structured motions were created by plotting target dots to form a rectangle (translational) or square (rotational) within the target area. From 22 to 1408 mask dots were added to the target displays. Percent correct data were obtained and masking functions created for each condition. Results: It is more difficult to mask biological motion compared to unstructured translational and unstructured rotational motion. However, there were only small differences in masking biological motion compared to structured translational and structured rotational motion. The data also showed that mask dot effectiveness depends on the size of the target display regardless of target type. Conclusions: The addition of structure in non-biological motion displays strongly influences performance in a masking paradigm. Given that structure is inherent in biological motion displays, comparing biological motion to structured non-biological motion seems to be a more reasonable comparison. In a detection task using a masking paradigm, there is little difference between biological motion and structured non-biological motion.