Thornton et al. (2002, Perception) showed that detection of point-light walkers (biological motion) embedded in noise is impaired in the presence of a competing change detection task (dual-task). Gurnsey et al. (2010, Journal of Vision) argued that the presence of masking noise dots was critical to this effect. Therefore, we measured walker direction discrimination thresholds with variable noise levels under single- and dual task conditions (change detection). For most subjects-as predicted--direction thresholds were identical under single- and dual-task conditions in the absence of noise, but thresholds increased with noise in the dual task condition. Hebb Award Abstract Thornton et al. (2002) asked observers to judge whether point-light walkers were heading ±90° from the line of sight while simultaneously performing a change detection task. They found walker direction discrimination was impaired in the presence of the competing task, suggesting that attention is critical to the detection of biological motion. However, a subsequent study by Gurnsey et al. (2010) showed that neither the addition of a colour discrimination task nor a radial frequency discrimination task impaired walker azimuth thresholds (the absolute angular difference from straight ahead). Although it is arguable that colour is separable from the form or motion information needed to discriminate walker direction the same cannot be said about the radial frequency task. It is possible that the discrepancy between these two results is related to Thornton et al.'s (2002) use of masking dots. Because the standard direction discrimination task is trivially easy in the absence of noise, Thompson et al. embedded their walkers in noise to limit performance. (This is common practice in the biological motion literature.) In the study by Gurnsey et al. (2010) azimuth thresholds at large sizes were ±1.5° on average. If biological motion is susceptible to resource competition then ±90° walkers should make fewer demands on attention than ±1.5° walkers. It may be that in the Thornton et al. study the observers' difficulty was with segregating walker from noise rather than with encoding the properties of the walker itself. In the present task we measured walker azimuth thresholds with and without noise in single- and dual-task conditions (as per Thornton et al., 2002). For four of our six observers we found that the competing task had no effect on thresholds in the absence of noise but thresholds increased linearly with noise in the dual task condition. This result is consistent with the idea noise impairs segmentation rather than sensitivity to properties of the walker. Three of these four subjects had extensive experience judging walkers in noise, and all four were avid video gamers. Two of our observers were impaired in the dual task even when no noise was present and exhibited much higher thresholds overall in the dual-task condition. One of these subjects had extensive experience judging point-light walkers without noise. Although we have evidence that noise alters the ability to segment walkers from noise, it seems that subject variables have a very large effect on performance in dual task experiments.