Tracking of unpredictable moving stimuli by pigeons

Despite being observed throughout the animal kingdom, catching a moving object is a complex task and little is known about the mechanisms that underlie this behavior in non-human animals. Three experiments examined the role of prediction in capture of a moving object by pigeons. In Experiment 1, a stimulus moved in a linear trajectory, but sometimes made an unexpected 90o turn. The sudden turn had only a modest effect on capture and error location, and the analyses suggested that the birds had adjusted their tracking to the novel motion. In Experiment 2, the role of visual input during a turn was tested by inserting disappearances (either 1.5 cm or 4.5 cm) on both the straight and turn trials. The addition of the disappearance had little effect on capture success, but delayed capture location with the larger disappearance leading to greater delay. Error analyses indicated that the birds adapted to the post-turn, post-disappearance motion. Experiment 3 tested the role of visual input when the motion disappeared behind an occluder and emerged in either a straight line or at a 90o angle. The occluder produced a disruption in capture success but did not delay capture. Error analyses indicated that the birds did not adjust their tracking to the new motion on turn trials following occlusion. The combined results indicate that pigeons can anticipate the future position of a stimulus, and can adapt to sudden, unpredictable changes in motion but do so better after a disappearance than after an occlusion

Tracking and capture of constant and varying velocity stimuli: a cross-species comparison of pigeons and humans

The mechanisms underlying tracking and capture of moving objects in non-human animals are poorly understood. This set of experiments sought to further explore aspects of anticipatory tracking in pigeons and to conduct comparisons with human participants. In Experiment 1a, pigeons were presented with two types of varying velocities (fast-slow-fast or slow-fast-slow) in separate phases. They were readily able to track and anticipate both of these motion types. To examine the effects of predictability on anticipatory tracking, Experiment 1b presented the pigeons with the same two varying velocities randomly intermixed within a session. This resulted in reduced capture success, later capture, and errors that no longer anticipated ahead of the motion, suggesting that the anticipatory mechanism had been disrupted. This implies that the mechanisms involved in pigeon tracking are different from the predictive extrapolation mechanism proposed in humans. Experiment 2 tested this by presenting adult humans with a tracking task that was similar to tasks previously received by the pigeons. The capture behavior of humans was similar to the pigeons, but the errors revealed different processes underlying their tracking behavior. © 2010 Springer-Verlag

Visually guided capture of a moving stimulus by the pigeon (Columba livia)

Although the pigeon is a popular model for studying visual perception, relatively little is known about its perception of motion. Three experiments examined the pigeons' ability to capture a moving stimulus. In Experiment 1, the effect of manipulating stimulus speed and the length of the stimulus was examined using a simple rightward linear motion. This revealed a clear effect of length on capture and speed on errors. Errors were mostly anticipatory and there appeared to be two processes contributing to response locations: anticipatory peck bias and lag time. Using the same birds as Experiment 1, Experiment 2 assessed transfer of tracking and capture to novel linear motions. The birds were able to capture other motion directions, but they displayed a strong rightward peck bias, indicating that they had learned to peck to the right of the stimulus in Experiment 1. Experiment 3 used the same task as Experiment 2 but with naïve birds. These birds did not show the rightward bias in pecking and instead pecked more evenly around the stimulus. The combined results indicate that the pigeon can engage in anticipatory tracking and capture of a moving stimulus, and that motion properties and training experience influence capture. © 2008 Springer-Verlag

Perceptual representations: a teleosemantic answer to the breadth-of-application problem

Schulte P. Perceptual representations: a teleosemantic answer to the breadth-of-application problem. Biology & Philosophy. 2015;30(1):119-136.Teleosemantic theories of representation are often criticized as being "too liberal", i.e. as categorizing states as representations which are not representational at all. Recently, a powerful version of this objection has been put forth by Tyler Burge. Focusing on perception, Burge defends the claim that all teleosemantic theories apply too broadly, thereby missing what is distinctive about representation. Contra Burge, I will argue in this paper that there is a teleosemantic account of perceptual states that does not fall prey to this problem, and that we can arrive at this account by combining some of Burge's insights with a producer-oriented version of teleosemantics. The resulting theory turns out to be attractive and perfectly coherent. By contrast, the coherence of Burge's own anti-teleosemantic approach becomes quite doubtful under closer examination-or so I will argue