Loss of form vision impairs spatial imagery

Abstract

Previous studies have reported inconsistent results when comparing spatial imagery performance in the blind and the sighted, with some, but not all, studies demonstrating deficits in the blind. Here, we investigated the effect of visual status and individual preferences ("cognitive style") on performance of a spatial imagery task. Participants with blindness resulting in the loss of form vision at or after age 6, and age-and gender-matched sighted participants, performed a spatial imagery task requiring memorization of a 4 × 4 lettered matrix and subsequent mental construction of shapes within the matrix from four-letter auditory cues. They also completed the Santa Barbara Sense of Direction Scale (SBSoDS) and a self-evaluation of cognitive style. The sighted participants also completed the Object-Spatial Imagery and Verbal Questionnaire (OSIVQ). Visual status affected performance on the spatial imagery task: the blind performed significantly worse than the sighted, independently of the age at which form vision was completely lost. Visual status did not affect the distribution of preferences based on self-reported cognitive style. Across all participants, self-reported verbalizer scores were significantly negatively correlated with accuracy on the spatial imagery task. There was a positive correlation between the SBSoDS score and accuracy on the spatial imagery task, across all participants, indicating that a better sense of direction is related to a more proficient spatial representation and that the imagery task indexes ecologically relevant spatial abilities. Moreover, the older the participants were, the worse their performance was, indicating a detrimental effect of age on spatial imagery performance. Thus, spatial skills represent an important target for rehabilitative approaches to visual impairment, and individual differences, which can modulate performance, should be taken into account in such approaches.

Enhanced verbal abilities in the congenitally blind

“…This contrasts with our earlier study of later-onset blindness (after age 6), in which performance on a spatial imagery task, similar to the present one except in using a 4 × 4 lettered matrix, was impaired in the late-blind compared to the sighted, independently of the age at which form vision was lost (Occelli et al, 2014). That the congenitally blind were not significantly worse than the sighted suggests that visual experience may not be necessary for the development of proficient spatial imagery or spatial memory.…”

Mental Imagery Follows Similar Cortical Reorganization as Perception: Intra-Modal and Cross-Modal Plasticity in Congenitally Blind

“…The neural basis of mental imagery within the intact auditory and haptic domains has been little researched in congenitally blind. The few studies that investigated haptic imagery focused on spatio-haptic tasks (Cattaneo et al 2007;Bonino et al 2008;Cornoldi et al 2009;Occelli et al 2014), or Braille reading (Heller 1989a;Buchel et al 1998;Cohen et al 2010;Striem-Amit et al 2012a). Auditory working memory studies showed superior performance in early blind (Roder et al 2001), which may be founded in superior encoding and consolidation (Stevens and Weaver 2005;Rokem and Ahissar 2009).…”

Graphomotor memory in Exner’s area enhances word learning in the blind

“…First, the relatively small sample size (12 blind and 18 sighted participants) in the present study may limit the reliability and generalizability of the behavioral and neural effects obtained. Second, while we relied on the notion that the long-term deprivation of visual inputs compromises visuospatial memory in the late-blind 29 , 30 , it should be further explored in future research how far residual visual memory contributes to word processing in those people. Third, our sample might consist of a heterogeneous group of blind participants since two of them had some experience in Braille reading.…”

“…It is therefore possible that, even in adulthood, motor codes of writing exert beneficial effects on word learning when visual or auditory sensory inputs are restricted. In particular, while the crossmodal interaction between the visual and phonological systems is thought to play a primary role in adult word learning 27 , 28 , such learning mechanism enhanced by literacy should be compromised by the long-term deprivation of visual inputs in the late-blind, which can attenuate visual memory retrieval 29 , 30 but may allow more cognitive resources for exploiting motor codes during word learning. We thus hypothesized that Exner’s area involved in the motor memory for handwriting should play a greater role in word learning for those blind people than for sighted people.…”