This paper presents a tactile vision substitution system (TVSS) for the study of active sensing. Two algorithms, namely image processing and trajectory tracking, were developed to enhance the capability of conventional TVSS. Image processing techniques were applied to reduce the artifacts and extract important features from the active camera and effectively converted the information into tactile stimuli with much lower resolution. A fixed camera was used to record the movement of the active camera. A trajectory tracking algorithm was developed to analyze the active sensing strategy of the TVSS users to explore the environment. The image processing subsystem showed advantageous improvement in extracting object's features for superior recognition. The trajectory tracking subsystem, on the other hand, enabled accurately locating the portion of the scene pointed by the active camera and providing profound information for the study of active sensing strategy applied by TVSS users.

Summary We examined the development of new sensing abilities in adults by training participants to perceive remote objects through their fingers. Using an Active-Sensing based sensory Substitution device (ASenSub), participants quickly learned to perceive fast via the new modality and preserved their high performance for more than 20 months. Both sighted and blind participants exhibited almost complete transfer of performance from 2D images to novel 3D physical objects. Perceptual accuracy and speed using the ASenSub were, on average, 300% and 600% better than previous reports for 2D images and 3D objects. This improvement is attributed to the ability of the participants to employ their own motor-sensory strategies. Sighted participants dominant strategy was based on motor-sensory convergence on the most informative regions of objects, similarly to fixation patterns in vision. Congenitally, blind participants did not show such a tendency, and many of their exploratory procedures resembled those observed with natural touch.

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