Abstract
Blind individuals have been shown on multiple occasions to compensate for their loss of sight by developing exceptional abilities in their remaining senses. While most research has been focused on perceptual abilities per se in the auditory and tactile modalities, recent work has also investigated higher-order processes involving memory and language functions. Here we examined tactile working memory for Braille in two groups of visually challenged individuals (completely blind subjects, CBS; blind with residual vision, BRV). In a first experimental procedure both groups were given a Braille tactile memory span task with and without articulatory suppression, while the BRV and a sighted group performed a visual version of the task. It was shown that the Braille tactile working memory (BrWM) of CBS individuals under articulatory suppression is as efficient as that of sighted individuals' visual working memory in the same condition. Moreover, the results suggest that BrWM may be more robust in the CBS than in the BRV subjects, thus pointing to the potential role of visual experience in shaping tactile working memory. A second experiment designed to assess the nature (spatial vs. verbal) of this working memory was then carried out with two new CBS and BRV groups having to perform the Braille task concurrently with a mental arithmetic task or a mental displacement of blocks task. We show that the disruption of memory was greatest when concurrently carrying out the mental displacement of blocks, indicating that the Braille tactile subsystem of working memory is likely spatial in nature in CBS. The results also point to the multimodal nature of working memory and show how experience can shape the development of its subcomponents.
Highlights
There has been an increasing interest in the study of blindness and its effects on cognition and behavior in recent years
The group by task interaction did not reach statistical significance (F = 0.48, p.0.05), as it can clearly be seen in Figure 1, the group difference is essentially attributable to the CBS performing better than the BRV subjects under articulatory suppression, as revealed by a post-hoc contrast analysis (p = 0.009)
The first experiment was an immediate serial recall task with and without articulatory suppression and was carried out in order to determine whether blind subjects possessed a tactile subsystem of working memory for Braille and, secondly, to determine whether the type of visual impairment (completely blind subjects (CBS) versus blind subjects with residual vision (BRV)) had any effect on its development
Summary
There has been an increasing interest in the study of blindness and its effects on cognition and behavior in recent years. Tactile and memory functions in blind individuals have received much attention, little is known about the existence of a tactile subsystem within the framework of the most generally accepted model of working memory proposed by Baddeley and Hitch [27,28,29,30]. This model consists of separate but interconnected subsystems, the most important of which is the central executive, which controls processes including access to the other subsystems as well as the retrieval of information stored in long-term memory. Behavioral studies have shown that visual perception is not essential for an efficient development of working memory [25,26], suggesting that other sensory modalities might compensate by providing the necessary spatial information
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