Sequential vs simultaneous encoding of spatial information: a comparison between the blind and the sighted (original) (raw)

Performance of Blind and Sighted Persons on Spatial Tasks

Journal of Visual Impairment & Blindness, 1995

This article reports on a study of the performance by congenitally blind, adventitiously blind, and sighted persons on three types of tasks: manipulatory, simple locomotion, and complex locomotion. The three groups of subjects tended to perform equivalently, and the results offer little evidence of a set of spatial processes that rely on past visual experience and are applicable to a broad variety of tasks. Numerous studies have assessed the ability of blind people to encode information about spatial layouts that they have explored with their hands, feet, or both and to use that information for such purposes as manipulation and navigation. Since the general focus of much of the research has been on the role of visual experience, many of these studies have compared the levels of performance of congenitally blind; adventitiously blind; and sighted, blindfolded subjects. These subjects' performance has been assessed with "tabletop" tasks, using stimuli manipulated by hand, and with tasks involving locomotion (these

Spatial representations in blind people: The role of strategies and mobility skills

The role of vision in the construction of spatial representations has been the object of numerous studies and heated debate. The core question of whether visual experience is necessary to form spatial representations has found different, often contradictory answers. The present paper examines mental images generated from verbal descriptions of spatial environments. Previous evidence had shown that blind individuals have difficulty remembering information about spatial environments. By testing a group of congenitally blind people, we replicated this result and found that it is also present when the overall mental model of the environment is assessed. This was not always the case, however, but appeared to correlate with some blind participants’ lower use of a mental imagery strategy and preference for a verbal rehearsal strategy, which was adopted particularly by blind people with more limited mobility skills. The more independent blind people who used a mental imagery strategy performed as well as sighted participants, suggesting that the difficulty blind people may have in processing spatial descriptions is not due to the absence of vision per se, but could be the consequence of both, their using less efficient verbal strategies and having poor mobility skills.

STRATEGIES FOR CONSTRUCTING SPATIAL REPRESENTATIONS USED BY BLIND AND SIGHTED SUBJECTS

The study was designed to investigate imagery strategies used by blind and sighted individuals and their ability to operate spatial representations. Performance accuracy in the imagery tasks was confirmed to be similar in the blind individuals with no visual memories and in the sighted subjects. On the other hand, the findings showed differences in preferred imagery strategies. The sighted, more often than the blind subjects, used the strategy of visualizing spatial matrices. The blind subjects applied a tapping strategy more often than the sighted ones. Additional analysis focused on the function of working memory systems in processing spatial stimuli by the blind and sighted subjects.

REPRESENTATION OF LOCOMOTOR SPACE BY THE BLIND

1987

Representation of locomotor space by early-and late-blind subjects and by blindfolded sighted subjects was studied within a perimeter where the direction and distance of landmarks had to be located. Subjects were guided along routes to be explored, both with and without the use of an ultr~sonic~holc;'Catingprosthesis that enabled object localization. Without the prosthesis, early-bhnd subjects performance was worse than that of visually experienced subjects both in direction and in distance assessments. With the help of the prosthesis, early-and Iate-hlind subjects' performance improved, especially in distance assessments; late-blinds' performance remained better than that of early-blinds. These results suggest that early-blinds' spatial representation would be the most impaired on routes requiring the mastering of euclidean concepts.

Navigating without vision: principles of blind spatial cognition

Handbook of Behavioral and Cognitive Geography

This chapter considers what it means to learn and navigate the world with limited or no vision. It investigates limitations of blindness research, discusses traditional theories of blind spatial abilities, and provides an alternative perspective of many of the oft-cited issues and challenges underlying spatial cognition of blind people. Several provocative assertions pertaining to visual impairment and spatial abilities are advanced that help to better understand navigation without vision, provide greater explanatory power relevant to many of the current debates, and offer some needed guidance on the development of new spatial learning strategies and technological solutions that will ultimately have a significant positive impact on the independence and quality of life of this demographic. An underlying and related theme of the chapter emphasizes the importance of 'space' in spatial cognition research, rather than vision as its principal mechanism. There is no debate that vision is an amazing conduit of spatial information, but it is also important to remember that it does not have a monopoly on space. Indeed, all of our senses encode spatial information to one degree or another, and as we will discuss, this commonality allows for equivalent performance on many of the same spatial behaviors, independent of whether they originate from visual or nonvisual perception.

Investigation of Blind Spatial Cognition and Understanding of Spaces to Navigate without Vision

Review of Applied Management and Social Sciences

This study is aimed to report the perspective of people with V.I about their use of spatial representation(cognitive maps) for determining the support level and applicability of cognitive maps while traveling on real routes. This research utilized the methodology of qualitative research in the form of semi structured interviews in order to obtain insights of persons having visual impairment about their navigation in different environments. The interviews were conducted with 20 persons having visual impairment working in different fields of life. The data analysis was done through thematic analysis approach. The participants were intended to answer the questions about the representation and understanding of space, the support level of these representations while traveling, and the role of other senses for successful navigation. The results showed that persons having visual impairment do have spatial representation and the creation of spatial representations does not require visual ex...

The Extemalization of Spatial Representation by Blind Persons

Journal of Visual Impairment & Blindness, 1992

This article compares two procedures for the externalization of spatial representation. Blind children and adolescents had to learn two unknown environments and to externalize the spatial representation by building a model and estimating distances. High correlations were found between the two externalization methods and between those methods and two systems of measuring mobility.

Nonvisual Navigation by Blind and Sighted - Assessment of Path Integration Ability

1993

Blindfolded sighted, adventitiously blind, and congenitally blind subjects performed a set of navigation tasks. The more complex tasks involved spatial inference and included retracing a multisegment route in reverse, returning directly to an origin after being led over linear segments, and pointing to targets after locomotion. As a group, subjects responded systematically to route manipulations in the complex tasks, but performance was poor. Patterns of error and response latency are informative about the internal repredentation used; in particular, they do not support the hypothesis that only a representation of the origin of locomotion is maintained. The slight performance differences between groups varying in visual experience were neither large nor consistent across tasks. Results provide little indication that spatial competence strongly depends on prior visual experience.

Spatial representation and processing in the congenitally blind

2004

Although there is consistent evidence for a deficit in the manipulation and internal representation of space and spatially located objects by the congenitally blind (e.g. Heller, 1989), explanations for this deficit are disputed. In this chapter, two accounts are examined for their ability to explain the experimental data, and recent data from a comparison of blind and sighted participants’ judgements of, and memory for, relative object locations are described, in an attempt to discriminate between these two accounts. Blind People’s Visuo-Spatial Performance Blind and sighted comparisons have been made on a wide variety of visuo – spatial tasks (e.g., those involving mental rotation, mental scanning, pathway memory and word imagery), always with the same result: the blind group performs either less accurately or more slowly than the sighted control group. However, the surprising finding has been the similar patterns of performance that are demonstrated by both sighted participants a...

THE ROLE OF VISUAL EXPERIENCE IN KNOWLEDGE OF SPATIAL LAYOUT

1980

Adventitiously blinded. congenitally blind, and sighted adults made relative distance judgments in a familiar environment under three sets of instructions-neutral with respect to the metric of comparison, euclidean (straight-line distance between landmarks), and functional (walking distance between landmarks). Analysis of error scores and multidimensional scaling procedures indicated that, although there were no significant differences among groups under functional instructions, all three groups differed from one another under euclidean instructions. Specifically, the sighted group performed best and the congenitally blind group worst, with the adventitiously blind group in between. The results are discussed in the context of the role of visual experience in spatial representation and the application of these methods for evaluating orientation and mobility training for the blind.