Here are some demonstrations of the various conditions discussed in the following paper: Gao, T., McCarthy, G., & Scholl, B. J. (2010). The wolfpack effect: Perception of animacy irresistibly influences interactive behavior. Psychological Science, 21(12), 1845-1853.These demonstrations are provided as MP4 movies, which can be downloaded or viewed directly in most web-browsers. These movies are a bit large and choppy, but they should be sufficient to illustrate the basic conditions. As highly compressed versions of the original stimuli, these movies may not preserve the precise spatial and temporal characteristics of the originals. The Wolfpack Effect Imagine a pack of predators stalking their prey. Such events appear to be richly animate, but why? An obvious cue is objective pursuit: the predators continually move towards their target. But not always: in some circumstances (e.g. when chasing a much larger animal), they may have to circle around their prey, in which case they may frequently be moving orthogonal to it (or even temporarily retreating), but still facing it. In other words, there may sometimes be a dissociation in such circumstances between the direction a predator is facing and the direction in which it is moving. Inspired by such natural phenomena, we predicted that the coordinated orientations of a group of moving shapes would automatically yield a percept of animacy when the shapes continually pointed towards a single target shape -- even if their actual motions were random.'Search-For-Chasing' Experiment Observers had to detect whether one dart (the wolf) chased -- i.e. was consistently displaced towards -- another disc (the sheep). The darts' orientations and the behavior of the green square were thus task-irrelevant. The animations provided here depict only 'Chase-Present' trials. (On Chase-Absent trials, the wolf was still present and moved in the same manner, but was 'chasing' an invisible sheep.) We provide each animation in two versions. One approximates the displays seen by the observers, in which all darts were featurally identical. In the other 'Cheat' version, the wolf is drawn in red, and the sheep is drawn in green. This may help to orient readers to conditions in which it is otherwise difficult to detect the chasing, but note that observers only ever saw monochromatic darts. As reported in the paper, the Wolfpack condition was the only condition that impaired the ability to discriminate Chase-Present from Chase-Absent trials.'Don't-Get-Caught' Experiment Participants controlled the movement of the green disk (the sheep) using the mouse to avoid being touched by the 'wolf' -- a disc that consistently moved toward the sheep -- while all other discs and darts moved randomly and were task-irrelevant. This task cannot be readily illustrated in premade animations, since it was inherently interactive. Here, instead, we depict 'played back' trials in which a sample participant completed the task. We again provide each animation in two versions. One approximates the displays seen by the observers, in which all darts were featurally identical. In the other 'Cheat' version, the wolf is drawn in red, and the sheep is drawn in green. This may help to orient readers to the subtler conditions, but note that our observers only ever saw monochromatic darts. As reported in the paper, the Wolfpack condition impaired participants' ability to detect and avoid the wolf relative to the Perpendicular condition.'Leave-Me-Alone' Experiment Participants moved a green disc about the display attempting to avoid contact with any of the white objects. Each quadrant contained 3 white objects. In two Wolfpack quadrants, each object was always oriented towards the user-controlled green disc. In two Perpendicular quadrants, each object was always oriented orthogonal to the user-controlled disc. This task cannot be readily illustrated in premade animations, since it was inherently interactive. Here, instead, we depict 'played back' trials in which a sample participant completed the task. As described in the paper, observers spent less time with the disc in the Wolfpack quadrants than in the Perpendicular quadrants.Hybrid 'Don't-Get-Caught'/'Leave-Me-Alone' Experiment In this hybrid of the Don't-Get-Caught and Leave-Me-Alone tasks, participants controlled the movement of the green disc using the mouse to avoid touching any of (1) the white darts, (2) the display border, or (3) the red 'wolf' disc that consistently moved toward the user-controlled green disc. Unlike the initial Don't-Get-Caught task, here participants did not struggle to determine the wolf's identity, since it was always displayed in a unique color. Unlike the initial Leave-Me-Alone task, one of the objects in the display (viz. the wolf) had a motion trajectory that was correlated to the movement of the user-controlled disc. This task cannot be readily illustrated in premade animations, since it was inherently interactive. Here, instead, we depict 'played back' trials in which a sample participant completed the task. As reported in the paper, performance was impaired in the Wolfpack-to-Sheep condition relative to both the Perpendicular-to-Sheep condition and the Wolfpack-to-Wolf condition -- and these effects were considerably larger than in the previous experiments. This demonstrates that the Wolfpack effect is a social effect: it matters in such situations whether the wolfpack is facing you instead of a third party. |