Mercedes Ximena Hüg

Sensorimotor strategies for recognizing geometrical shapes: a comparative study with different sensory substitution devices.

The sensorimotor approach proposes that perception is constituted by the mastery of lawful sensorimotor regularities or sensorimotor contingencies (SMCs), which depend on specific bodily characteristics and on actions possibilities that the environment enables and constrains. Sensory substitution devices (SSDs) provide the user information about the world typically corresponding to one sensory modality through the stimulation of another modality. We investigate how perception emerges in novice adult participants equipped with vision-to-auditory SSDs while solving a simple geometrical shape recognition task. In particular, we examine the distinction between apparatus-related SMCs (those originating mostly in properties of the perceptual system) and object-related SMCs (those mostly connected with the perceptual task). We study the sensorimotor strategies employed by participants in three experiments with three different SSDs: a minimalist head-mounted SSD, a traditional, also head-mounted SSD (the vOICe) and an enhanced, hand-held echolocation device. Motor activity and fist-person data are registered and analyzed. Results show that participants are able to quickly learn the necessary skills to distinguish geometric shapes. Comparing the sensorimotor strategies utilized with each SSD we identify differential features of the sensorimotor patterns attributable mostly to the device, which account for the emergence of apparatus-based SMCs. These relate to differences in sweeping strategies between SSDs. We identify, also, components related to the emergence of object-related SMCs. These relate mostly to exploratory movements around the border of a shape. The study provides empirical support for SMC theory and discusses considerations about the nature of perception in sensory substitution.

Auditory localization and precedence effect: An exploratory study in infants and toddlers with visual impairment and normal vision

The precedence effect is a spatial hearing phenomenon implicated in sound localization on reverberant environments. It occurs when a pair of sounds, with a brief delay between them, is presented from different directions; listeners give greater perceptual weight to localization cues coming from the first-arriving sound, called lead, and suppress localization cues from the later-arriving reflection, called lag. Developmental studies with sighted infants show that the first responses to precedence effect stimuli are observed at 4-5 months of life. In this exploratory study, we use the minimum audible angle (MAA) paradigm in conjunction with the observer-based psychophysical procedure to test the ability of infants and toddlers, with visual impairment and normal vision, to discriminate changes in the azimuthal position of sounds configured under precedence effect conditions. The results indicated that similar and, in some conditions, higher performances were obtained by blind toddlers when compared to sighted children of similar age, and revealed that the observer-based psychophysical procedure is a valuable method to measure auditory localization acuity in infants and toddlers with visual impairment. The video records showed auditory orienting behaviors specific of the blind children group.

CINTRA: from an interdisciplinary centre on acoustics towards an intra-inter synergetic network

Acoustics is an inherently interdisciplinary science involved in the study and remediation of very hot social topics. For its part, the university has a crucial role in knowledge generation with social responsibility heading to an equalitarian society. Argentinean scientific policy, promotes: a) interdisciplinary and inter institutional scientific teams, b) an unified national system of science and technology and c) the linkage of this system with educational and productive sectors. At the same time, new paradigms of higher education give a central place to the student learning process of research abilities. In such complex scenario a research center has a key role in achieving these goals. Nowadays CINTRA (Centro de Investigacion y Transferencia en Acustica) is involved in a collective construction pointing towards innovative dynamics encouraging the emergence of synergetic networks in which theory-practice and research-technology are naturally joined. This paper describes three CINTRA’s ongoing programs...