Memory for sounds: novel technological solutions for the evaluation of mnestic skills

Working memory (WM) plays a crucial role in helping individuals to perform everyday activities. The neural structures underlying this system continue to develop during infancy and reach maturity only late in development. Despite useful insights into visual memory mechanisms, audio-spatial memory has not been thoroughly investigated, especially in children and congenitally blind individuals. The main scientific objective of this thesis was to increase knowledge of spatial WM and imagery abilities in the auditory modality. We focused on how these skills change during typical development and on the consequences of early visual deprivation. Our first hypothesis was that the changes in WM functionality and spatial skills occurring in the early years of life, influence the ability to remember and associate spatialized sounds or to explore and learn acoustic spatial layouts. Since vision plays a crucial role in spatial cognition (ThinusBlanc and Gaunet, 1997), we expected blind individuals to encounter specific difficulties when asked to process and manipulate spatial information retained in memory, as already observed in the haptic modality (Cattaneo et al., 2008; Vecchi, 1998). Although some studies demonstrated the superior performance of the blind in various verbal-memory tasks (Amedi et al., 2003; Požár, 1982; Röder et al., 2001), very little is known on how they remember and manipulate acoustic spatial information. The investigation of auditory cognition often requires specially adapted hardware and software solutions rarely available on the market. For example, in the case of studying cognitive functions that involve auditory spatial information, multiple acoustic spatial locations are required, such as numerous speakers or dedicated virtual acoustics. Thus, to the aim of this thesis, we took advantage of novel technological solutions developed explicitly for delivering non-visual spatialized stimuli. We worked on the software development of a vertical array of speakers (ARENA2D), an audio-tactile tablet (Audiobrush), and we designed a system based on an acoustic virtual reality (VR) simulation. These novel solutions were used to adapt validated clinical procedures (Corsi-Block test) and games (the card game Memory) to the auditory domain, to be also performed by visually impaired individuals. Thanks to the technologies developed in these years, we could investigate these topics and observed that audio-spatial memory abilities are strongly affected by the developmental stage and the lack of visual experience.