The visual-perceptual space is our internal representation of the visual world around us. In order to be useful to our behavior, it must be continually updated in response to sensory input by mapping input from the retinas onto the relevant locations in perceptual space. This mapping needs to remain accurate throughout life despite physical changes such as growth and aging and possibly even damage to parts of the visual system. Consequently, there must be mechanisms that recalibrate this mapping. In fact, it was found that when observers'vision is artificially distorted, for example, through prism glasses, subjects quickly return to almost their previous level of performance in an object grasping task if they receive both visual and haptic feedback. Recently, our lab demonstrated a different mechanism of remapping visual-perceptual space by means of a novel technique of continuous adaptation of saccadic eye movements across amplitudes and directions. In a preliminary study, we showed that after reducing the amplitude of either the horizontal or vertical component of participants'saccadic eye movements across many saccadic vectors, perceptual judgments about the relative lengths of the bars in a persistent """"""""cross figure"""""""" are distorted, even during fixation. Consequently, it appears that adjustments to the motor areas involved in planning or executing volitional saccades are accompanied by changes to spatial perception, suggesting that the two systems possibly utilize the same neuronal areas to establish their representation of visual space. The proposed project is aimed at performing a fine-grained analysis of the observed effect and utilizing it to introduce another novel research paradigm. Specifically, one of our experiments will study the contribution of covert shifts of attention and eye movements on subjects'perception after whole-field, anisotropic saccadic adaptation. This effort is aimed at establishing a theoretical framework of the perceptual adaptation effects. Another experiment is aimed at gaining a more detailed view of the geometry of the remapping of perceptual space and how it relates to the geometry of saccadic adaptation. For this purpose, the patterns of induced anisotropic saccadic adaptation will not only include vertical and horizontal adaptation, but also diagonal adaptation. Most importantly, a more detailed method of perceptual judgment will be applied. Subjects will adjust the position of the corners of a random polygon in order to turn it into a regular polygon, that is, a polygon with identical angles and edge lengths. Finally, a third experiment will study motion perception in distorted visual-perceptual space. In particular, it will examine possible changes in the relationship between perceived speed and the velocity of smooth pursuit eye movements due to the remapping of perceptual space. Comparing the effects of the adaptation method on these two variables will add valuable evidence to the current debate about the neurophysiological dissociation between perception and action in vision. Moreover, this experiment will introduce motion perception in distorted perceptual space as a novel research paradigm that addresses not only the link between distance and motion perception, but also the larger theoretical issue of perception- versus-action in vision.
The proposed study will enhance our understanding of the mechanisms underlying the plasticity of our visual-perceptual space, that is, our everyday visual perception. A novel, computer-based technique promises to provide insight into these mechanisms from a new perspective.
| Luo, Gang; Garaas, Tyler; Pomplun, Marc (2014) Salient stimulus attracts focus of peri-saccadic mislocalization. Vision Res 100:93-8 |
| Garaas, Tyler W; Pomplun, Marc (2011) Distorted object perception following whole-field adaptation of saccadic eye movements. J Vis 11:2 |
| Luo, Gang; Garaas, Tyler; Pomplun, Marc et al. (2010) Inconsistency between peri-saccadic mislocalization and compression: evidence for separate ""what"" and ""where"" visual systems. J Vis 10:32 |
