Head-mounted sensors reveal visual attention of free-flying homing pigeons

In human vision, acuity and color sensitivity are best at the point of fixation, and the visual-cognitive system exploits this fact by actively controlling gaze to direct fixation towards important and informative scene regions in real time as needed. How gaze control operates over complex real-world scenes has recently become of central concern in several core cognitive science disciplines including cognitive psychology, visual neuroscience, and machine vision. This article reviews current approaches and empirical findings in human gaze control during real-world scene perception.

Steering a car requires visual information from the changing pattern of the road ahead. There are many theories about what features a driver might use, and recent attempts to engineer self-steering vehicles have sharpened interest in the mechanisms involved. However, there is little direct information linking steering performance to the driver's direction of gaze. We have made simultaneous recordings of steering-wheel angle and drivers' gaze direction during a series of drives along a tortuous road. We found that drivers rely particularly on the 'tangent point' on the inside of each curve, seeking this point 1-2 s before each bend and returning to it throughout the bend. The direction of this point relative to the car's heading predicts the curvature of the road ahead, and we examine the way this information is used.

Animals that travel together in groups display a variety of fascinating motion patterns thought to be the result of delicate local interactions among group members. Although the most informative way of investigating and interpreting collective movement phenomena would be afforded by the collection of high-resolution spatiotemporal data from moving individuals, such data are scarce and are virtually non-existent for long-distance group motion within a natural setting because of the associated technological difficulties. Here we present results of experiments in which track logs of homing pigeons flying in flocks of up to 10 individuals have been obtained by high-resolution lightweight GPS devices and analyzed using a variety of correlation functions inspired by approaches common in statistical physics. We find a well-defined hierarchy among flock members from data concerning leading roles in pairwise interactions, defined on the basis of characteristic delay times between birds' directional choices. The average spatial position of a pigeon within the flock strongly correlates with its place in the hierarchy, and birds respond more quickly to conspecifics perceived primarily through the left eye - both results revealing differential roles for birds that assume different positions with respect to flock-mates. From an evolutionary perspective, our results suggest that hierarchical organisation of group flight may be more efficient than an egalitarian one, at least for those flock sizes that permit regular pairwise interactions among group members, during which leader-follower relationships are consistently manifested.