REVEALING THE SPEED OF IMPLIED MOTION SIGNALS ASSOCIATED WITH VIEWING OTHER PEOPLE’S GAZE

Recent evidence has shown that exposure to static images depicting an agent actively gazing at an object leads to a motion adaptation effect in the direction of the gaze, suggesting that the attention of others is encoded as an implied agent-to-object motion. Across three experiments, we examined whether this motion signal is associated with a specific speed, exploiting the reported property of motion adaptation that it is strongest when the test stimulus closely matches the adapting stimulus. In experiment 1, participants (n = 25) viewed the same static image used in previous studies and subsequently made a forced-choice response to test probes with differing speeds of dot motion. Experiment 2 was identical to experiment 1, except that the agent in the image was blindfolded. In experiment 3, participants (n = 30) viewed a subtle, real motion stimulus in the location corresponding to the space between the eyes of the agent and the tree in experiment 1. Following exposure to the image of an agent actively gazing at a tree, a peak significant motion adaptation effect was found for dot motion with a speed of 1.4°/s. The effect disappeared when the agent was blindfolded. Moreover, adaptation to real motion at 1.4°/s was indeed strongest when the test probe speed closely matched the adapting stimulus, suggesting similar underlying mechanisms. These findings strongly suggest that people encode others’ gaze as an implied motion linking agents to attended objects, and that this internally generated motion signal travels at a specific ‘speed’.