Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual \"filling in,\" visual stability despite eye movements, change blindness, sensory substitution, and color perception.

A sensorimotor account of vision and visual consciousness-Authors' Response-Acting out our sensory experience

Sensory processing of action effects has been shown to differ from that of externally triggered stimuli, with respect both to the perceived timing of their occurrence (intentional binding) and to their intensity (sensory attenuation). These phenomena are normally attributed to forward action models, such that when action prediction is consistent with changes in our environment, our experience of these effects is altered. Although much progress has been made in recent years in understanding sensory attenuation and intentional binding, a number of important questions regarding the precise nature of the predictive mechanisms involved remain unanswered. Moreover, these mechanisms are often not discussed in empirical papers, and a comprehensive review of these issues is yet to appear. This review attempts to fill this void. We systematically investigated the role of temporal prediction, temporal control, identity prediction, and motor prediction in previous published reports of sensory attenuation and intentional binding. By isolating the individual processes that have previously been contrasted and incorporating these experiments with research in the related fields of temporal attention and stimulus expectation, we assessed the degree to which existing data provide evidence for the role of forward action models in these phenomena. We further propose a number of avenues for future research, which may help to better determine the role of motor prediction in processing of voluntary action effects, as well as to improve understanding of how these phenomena might fit within a general predictive processing framework. Furthermore, our analysis has important implications for understanding disorders of agency in schizophrenia.

Mechanisms of intentional binding and sensory attenuation: The role of temporal prediction, temporal control, identity prediction, and motor prediction.

Action effect anticipation: Neurophysiological basis and functional consequences

Due to the inhomogenous visual representation across the visual field, humans use peripheral vision to select objects of interest and foveate them by saccadic eye movements for further scrutiny. Thus, there is usually peripheral information available before and foveal information after a saccade. In this study we investigated the integration of information across saccades. We measured reliabilities--i.e., the inverse of variance-separately in a presaccadic peripheral and a postsaccadic foveal orientation--discrimination task. From this, we predicted trans-saccadic performance and compared it to observed values. We show that the integration of incongruent peripheral and foveal information is biased according to their relative reliabilities and that the reliability of the trans-saccadic information equals the sum of the peripheral and foveal reliabilities. Both results are consistent with and indistinguishable from statistically optimal integration according to the maximum-likelihood principle. Additionally, we tracked the gathering of information around the time of the saccade with high temporal precision by using a reverse correlation method. Information gathering starts to decline between 100 and 50 ms before saccade onset and recovers immediately after saccade offset. Altogether, these findings show that the human visual system can effectively use peripheral and foveal information about object features and that visual perception does not simply correspond to disconnected snapshots during each fixation.

http://geb.uni-giessen.de/geb/volltexte/2016/12008/pdf/10.1167_15.16.1.pdf

Trans-saccadic integration of peripheral and foveal feature information is close to optimal.

Selective attention and the active remapping of object features in trans-saccadic perception.

Sensorimotor adaptation can be defined as a perceptual adaptation whose effects depend on the occurrence and nature of the performed motor actions. Examples of sensorimotor adaptation can be found in the literature on prisms concerning several space-related attributes like orientation, curvature, and size. In this article, we show that sensorimotor adaptation can be obtained for color, as a consequence of the introduction of a new sensorimotor contingency between eye movements and color changes. In an adaptation phase, trials involved the successive presentation of two patches, first on the left, and then on the right or the opposite. The left patch being always red and the right patch green, a correlation is introduced between left–right (respectively right–left) eye saccades and red–green (respectively green–red) color change. After 40 min of adaptation, when two yellow patches are successively presented on each side of the screen, the chromaticity of the left and right patches need respectively to be shifted toward the chromaticity of the red and green adaptation patches for subjective equality to be obtained. When the eyes are kept fixed during the adaptation stage, creating a strong nonhomogeneity in retinal adaptation, no effect is found. This ensures that, if present, adaptation at a given retinal location cannot explain the present effect. A third experiment shows a dependency of the effect on the eyes' saccadic movements and not on the position on the screen, that is, on the position of the eyes in the orbits. These results argue for the involvement of sensorimotor mechanisms in color perception. The relation of these experimental findings toward a sensorimotor theory of color perception is discussed.

/pdf/more-evidence-for-sensorimotor-adaptation-in-color-q5v4v7oh93.pdf

J. K. O'Regan

Papers

More evidence for sensorimotor adaptation in color perception.