Interaction of cognitive and sensorimotor maps of visual space

Abstract

Studies of saccadic suppression and induced motion have suggested separate representations of visual space for perception and visually guided behavior. Because these methods required stimulus motion, subjects might have confounded motion and position. We separated cognitive and sensorimotor maps without motion of target, background, or eye, with an "induced Roelofs effect": a target inside an off-center frame appears biased opposite the direction of the frame. A frame displayed to the left of a subject's center line, for example, will make a target inside the frame appear farther to the right than its actual position. The effect always influences perception, but in half of our subjects it did not influence pointing. Cognitive and sensorimotor maps interacted when the motor response was delayed; all subjects now showed a Roelofs effect for pointing, suggesting that the motor system was being fed from the biased cognitive map. A second experiment showed similar results when subjects made an open-ended cognitive response instead of a five-alternative forced choice. Experiment 3 showed that the results were not due to shifts in subjects' perception of the felt straight-ahead position. In Experiment 4, subjects pointed to the target and judged its location on the same trial. Both measures showed a Roelofs effect, indicating that each trial was treated as a single event and that the cognitive representation was accessed to localize this event in both response modes.Several topographic maps represent the visual world in the cortex (Felleman & Van Essen, 1991). This characteristic of the visual system raises a question for visual physiology: do all of these maps work together to create a single representation of visual space, or are they functionally distinct? If they are distinct, how many functional maps are there and how do they communicate with one another? This paper presents psychophysical evidence for at least two functionally distinct representations of the visual world in normal humans; under some conditions, the two representations can simultaneously hold different spatial values. The paper also demonstrates some of the ways in which the representations communicate with one another.An early hint that cognitive and sensorimotor systems are separable in normal humans came from studies of eye movements. On the one hand, subjects are unaware ofsizable displacements of the visual world if they occur during saccadic eye movements, implying that information about spatial location is degraded during saccades (Bridgeman,

Pointing and Visual Feedback for Spatial Interaction in Large-Screen Display Environments

“…The first two conditions in our study test this prediction and essentially replicate Bridgeman et al [2], but in a setting more typical of large-screen collaborative environments.…”

“…The first step in our research was a pilot study that successfully reproduced the previous laboratory findings of Bridgeman et al [2], but in a setting more representative of collaborative and immersive display environments. This demonstrated that a displaced frame surrounding a target will cause some participants to make systematic errors in verbally reported location judgments but not in pointing without visual feedback (also known as "open-loop" pointing in experimental psychology).…”

“…Past studies in experimental psychology show that the choice of mental representation that is used in a particular spatial motor interaction, such as pointing, is strongly influenced by the level of visual feedback that is provided to participants [2,11]. These studies also suggest that spatial references to objects through a non-motor interaction will consistently draw from the cognitive representation of space, with the result that non-motor interactions are highly subject to perceptual biases by a broad range of visual illusions.…”

“…Central to this is a model of human cognition and motor processes that is known as the two visual systems hypothesis [2,11,19]. The hypothesis claims that visually-guided action can be mediated by either or both of two separate mental representations of space: a cognitive representation, which generates a world-relative view of visually-perceived objects in surrounding space, and a sensorimotor representation, which generates an egocentric view of these same objects.…”

“…This demonstrated that a displaced frame surrounding a target will cause some participants to make systematic errors in verbally reported location judgments but not in pointing without visual feedback (also known as "open-loop" pointing in experimental psychology). The classic work on this is known as the Induced Roelofs Effect [2,18], part of the theoretical framework for our research.…”