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Patrice D Tremoulet

Publications and source records attributed to Patrice D Tremoulet.

2 recordsLinked to original sources

The influence of spatial context and the role of intentionality in the interpretation of animacy from motion.

We present three experiments investigating how spatial context influences the attribution of animacy to a moving target. Each of our displays contained a moving object (the target) that might, depending on the way it moved, convey the impression that it was alive (animate). We investigated the mechanisms underlying this attribution by manipulating the nature of the spatial context surrounding the target. In Experiment 1, the context consisted of a simple static dot (the foil), whose position relative to the target's trajectory was manipulated. With some foil positions--for example, when the foil was lying along the path traveled by the target--animacy judgments were elevated relative to control foil locations, apparently because this context supported the impression that the target was "reacting to" or was in some other way mentally influenced by the foil. In Experiment 2, contexts consisted of a static oriented rectangle (the "paddle"). On some trials, the target collided with the paddle in a way that seemed to physically account for the target's motion pattern (in the sense of having imparted momentum to it); this condition reduced animacy ratings. Experiment 3 was similar, except that the paddles themselves were in motion; again, animacy attribution was suppressed when the target's motion seemed to have been caused by a collision with the paddle. Hence, animacy attributions can be either elevated or suppressed by the nature of the environment and the target's interaction with it. Animacy attribution tracks intentionality attribution; contrary to some earlier proposals, we conclude that attributing animacy involves, and may even require, attributing to the target some minimal mental capacity sufficient to endow the target with intentionality.

Humans↗

Individuation of visual objects over time.

How does an observer decide that a particular object viewed at one time is actually the same object as one viewed at a different time? We explored this question using an experimental task in which an observer views two objects as they simultaneously approach an occluder, disappear behind the occluder, and re-emerge from behind the occluder, having switched paths. In this situation the observer either sees both objects continue straight behind the occluder (called "streaming") or sees them collide with each other and switch directions ("bouncing"). This task has been studied in the literature on motion perception, where interest has centered on manipulating spatiotemporal aspects of the motion paths (e.g. velocity, acceleration). Here we instead focus on featural properties (size, luminance, and shape) of the objects. We studied the way degrees and types of featural dissimilarity between the two objects influence the percept of bouncing vs. streaming. When there is no featural difference, the preference for straight motion paths dominates, and streaming is usually seen. But when featural differences increase, the preponderance of bounce responses increases. That is, subjects prefer the motion trajectory in which each continuously existing individual object trajectory contains minimal featural change. Under this model, the data reveal in detail exactly what magnitudes of each type of featural change subjects implicitly regard as reasonably consistent with a continuously existing object. This suggests a simple mathematical definition of "individual object:" an object is a path through feature-trajectory space that minimizes feature change, or, more succinctly, an object is a geodesic in Mahalanobis feature space.

Bayes Theorem↗