Superior tactile abilities in the blind: is blindness required?

Editor's Note: These short, critical reviews of recent papers in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to summarize the important findings of the paper and provide additional insight and commentary. For more information on the format and purpose of the Journal Club, please see Review of Wong et al. How blindness affects a person's other senses has been questioned for some time. One of the primary debates revolved around whether blind individuals would be handicapped beyond the visual realm, given vision's roles in the construction of spatial concepts and for spatial calibration of other senses, or if on the other hand, these functions would be taken over by heightened abilities in the remaining senses. The latter is suggested by numerous anecdotal stories about blind individuals' prowess with auditory and tactile senses, as well as by studies that show enhanced abilities in the blind for both the auditory (Collignon et al., 2009) and tactile (Sathian and Stilla, 2010) domains. These studies have led researchers to explore the driving force underlying these improved abilities. Some of this improvement is likely mediated by massive cross-modal plasticity: areas of the occipital cortex in blind individuals become highly responsive to nonvisual input. Superior behavioral abilities might require the extra cerebral resources allotted to auditory and tactile processing following blindness. On the other hand, blind individuals benefit from extensive training in the auditory and tactile modalities , and this additional experience may be the more important factor underlying superior abilities. In their recent article published in The Journal of Neuroscience, Wong et al. (2011) examined whether superior ability of blind individuals in a grating orientation task (GOT) was the consequence of visual deprivation alone or whether tactile experience-dependent mechanisms were the key determinant. The authors followed up on a previous study showing that tactile acuity is enhanced in blindness (Goldreich and Kanics, 2003), and they compared the passive tactile spatial acuity on the index, middle, and ring fingers of blind participants with varying levels of Braille expertise to that of sighted participants. The variation in Braille expertise allowed them to assess the effect of tactile training on performance on the GOT. As an additional control condition, acuity was also assessed on the lips, where blind and sighted individuals are more likely to have similar tactile experience compared to fingers. Several results obtained by Wong et al. (2011) highlight the importance …