Evaluating Performance after Training: the Recognition of Pictures by Touch

The present study evaluated the performance of congenitally blind people at recognizing twodimensional picture by touch, after a 45 hour training. Totally blind individuals served as observers in a haptically recognition task, both, before and after being trained at naming twodimensional raised-line drawings. Statistical analysis showed a significant effect of training with planar configurations. Visual mediation was proved not necessary for picture recognition, since blind individuals had a cogent development at naming picture by touch. Some suggestions for improving blind people’s performance at recognizing raised-line drawings are offered. A number of studies have been carried out in order to understand the sense of touch, due to the importance of this sense to the human life. Those interested in the area are referred to Heller (2000, 1991), Millar (1991), Katz (1989) Loomis and Lederman (1986), Schiff and Folke (1982) for a comprehensive presentation and discussion of the latest researches on the haptic system. Though considered by Aristotle as the most necessary sense, the sense of touch was also considered as a secondary sense by that philosopher, to whom vision is superior to all senses, since it is the sense that best judges and gives the most important and precise details about space, pictures etc (in Aquinas, 1995). This view is not too different from that of the laymen, to whom the lack of vision of the blind individuals means that these people are disabled, deficient and piteous, nor is it too different from that of the scientists, who have been studying the haptic sense. There have been very few studies on touch, if compared with the innumerous researches on vision. Most of the few researches on touch come to conclusions that can be divided into three camps. “One group suggests that vision is the spatial sense par excellence. This group suggests that congenitally blind individuals (blind from birth) are incapable of spatial thought because they have never experienced the perceptual processes (e.g., vision) necessary to comprehend spatial arrangements. Another group suggests that people with visual impairments can understand and mentally manipulate spatial concepts, but because information is based upon auditory and haptic cues this knowledge and comprehension is inferior to that based upon vision. The third group suggests that visually impaired individuals possess the same abilities to process and understand spatial concepts and that any differences, either in quantitative or qualitative terms, can be explained by intervening variables such as access to information, experience or stress” (Kitchin, Blades & Golledge, 1997). A series of these studies compare blindfolded sighted subjects with congenitally blind individuals. According to Heller (1991), he interest in the congenitally blind people is because these individuals have had no vision experience and are touch dependant to acquire knowledge from the world. Many experiments, including those of psychophysics, require in one way or the other, knowledge or abilities, which are most commonly developed in the sighted. For instance, the ability of using maps, drawings, pictures and other two-dimensional patterns to represent tangible or non-tangible 3D objects. In tasks of picture recognition, drawings are made tangible for experimenting with blind subjects. However, It is not known whether this is enough for making these configurations more comprehensive for the haptic system and the blind. Blind individuals are invariably compared with blindfolded sighted subjects who have a whole life of experience with recognizing or making pictures and other complex planar configurations. For the most part, however, the visually impaired people have never been taught how to recognize pictures by touch or how planar configurations can be used to represent the 3dimensional world with its conventions and pictorial language. Among the facts that can interfere in a task is the recruiting of the subjects. Some of the blind observers have been recruited from institutions. These people may have a rather different, limited living experience compared with that of the blind individuals who live with their families or by themselves and interact more with the sighted and the sighted world. This living experience may help these people to better understand visual explanations of the task, that is these people may better understand what a sighted person means by, for example, perspective view a bird’s eye view foreshortening etc. Social linguistics has shown the importance of language register when answering a demanded task. A blind person may not understand fully what is being requested for he may not be sharing the same vocabularies, though he may know what that word means in the dictionary. Touch is known to be slower than vision for acquiring some information due to the fact that it obtains information sequentially (Loomis, Klatsky & Lederman, 1991). However, some of the raised-line patterns used in haptic recognition tasks are made in rather large-scale drawings, which may cause a burden on memory. In fact, it is not known which size picture is better for tactile recognition, nor is it known what details should be included or excluded for a better haptic recognition. These questions illustrate the need for a more complete study to learn weather blind people can really make sense of a two-dimensional picture, since just comparing their performance in naming drawings with that of the blindfolded sighted subjects would give a rather restrict understanding of the haptic sense and of the capability of the blind in resolving picture recognition tasks. In order to address some of these questions, we investigated the capability of blind people in recognizing picture by touch, by comparing their own performance before and after training them with planar configurations. If the blind individuals showed a significant development in picture naming, after being trained with two-dimensional patterns, this would indicate that visual mediation is not necessary for making sense of raised-line drawing and that touch can be trained to resolve picture recognition task.