Picture and pattern perception in the sighted and the blind: the advantage of the late blind

Adults' spatial scaling of tactile maps: Insights from studying sighted, early and late blind individuals

The current study investigated spatial scaling of tactile maps among blind adults and blindfolded sighted controls. We were specifically interested in identifying spatial scaling strategies as well as effects of different scaling directions (up versus down) on participants' performance. To this aim, we asked late blind participants (with visual memory, Experiment 1) and early blind participants (without visual memory, Experiment 2) as well as sighted blindfolded controls to encode a map including a target and to place a response disc at the same spot on an empty, constant-sized referent space. Maps had five different sizes resulting in five scaling factors (1:3, 1:2, 1:1, 2:1, 3:1), allowing to investigate different scaling directions (up and down) in a single, comprehensive design. Accuracy and speed of learning about the target location as well as responding served as dependent variables. We hypothesized that participants who can use visual mental representations (i.e., late blind and blindfolded sighted participants) may adopt mental transformation scaling strategies. However, our results did not support this hypothesis. At the same time, we predicted the usage of relative distance scaling strategies in early blind participants, which was supported by our findings. Moreover, our results suggested that tactile maps can be scaled as accurately and even faster by blind participants than by sighted participants. Furthermore, irrespective of the visual status, participants of each visual status group gravitated their responses towards the center of the space. Overall, it seems that a lack of visual imagery does not impair early blind adults' spatial scaling ability but causes them to use a different strategy than sighted and late blind individuals.

A Systematic Review of Tactile Functioning in Blind Children From a Clinical Perspective

In the literature, there is a lot of variation in how well visually impaired youngsters can distinguish between tactile images. This systematic review investigated tactile functioning approaches' clinical perspective on blind children. PubMed, SCOPUS, Web of Science, Science Direct, and Cochrane Library were systematically searched to include the relevant literature. Rayyan QCRI was used throughout this systematic approach. The study included nine studies with a total of 394 children, 246 (62.4%) were males, and 148 (37.6%) were females. Textured graphical objects, images, drawings, and illustrations were used as stimuli to test tactile functioning in blind children. The findings of this comprehensive review showed that tactile stimuli for blind children were most effective in the form of textured images, words, and objects. It has been shown that the complexity, familiarity, and category information all influence how easy or challenging picture recognition is. Blind people can effectively use pictorial displays, but when foreshortening is used in complex representations of three-dimensional objects, they may benefit from instruction.

Drawing as a tool for investigating the nature of imagery representations of blind people: The case of the canonical size phenomenon

Several studies have shown that blind people, including those with congenital blindness, can use raised-line drawings, both for "reading" tactile graphics and for drawing unassisted. However, research on drawings produced by blind people has mainly been qualitative. The current experimental study was designed to investigate the under-researched issue of the size of drawings created by people with blindness. Participants (N = 59) varied in their visual status. Adventitiously blind people had previous visual experience and might use visual representations (e.g., when visualising objects in imagery/working memory). Congenitally blind people did not have any visual experience. The participant's task was to draw from memory common objects that vary in size in the real world. The findings revealed that both groups of participants produced larger drawings of objects that have larger actual sizes. This means that the size of familiar objects is a property of blind people's mental representations, regardless of their visual status. Our research also sheds light on the nature of the phenomenon of canonical size. Since we have found the canonical size effect in a group of people who are blind from birth, the assumption of the visual nature of this phenomenon - caused by the ocular-centric biases present in studies on drawing performance - should be revised.

Cognitive map formation in the blind is enhanced by three-dimensional tactile information

For blind individuals, tactile maps are useful tools to form cognitive maps through touch. However, they still experience challenges in cognitive map formation and independent navigation. Three-dimensional (3D) tactile information is thus increasingly being considered to convey enriched spatial information, but it remains unclear if it can facilitate cognitive map formation compared to traditional two-dimensional (2D) tactile information. Consequently, the present study investigated the impact of the type of sensory input (tactile 2D vs. tactile 3D vs. a visual control condition) on cognitive map formation. To do so, early blind (EB, n = 13), late blind (LB, n = 12), and sighted control (SC, n = 14) participants were tasked to learn the layouts of mazes produced with different sensory information (tactile 2D vs. tactile 3D vs. visual control) and to infer routes from memory. Results show that EB manifested stronger cognitive map formation with 3D mazes, LB performed equally well with 2D and 3D tactile mazes, and SC manifested equivalent cognitive map formation with visual and 3D tactile mazes but were negatively impacted by 2D tactile mazes. 3D tactile maps therefore have the potential to improve spatial learning for EB and newly blind individuals through a reduction of cognitive overload. Installation of 3D tactile maps in public spaces should be considered to promote universal accessibility and reduce blind individuals' wayfinding deficits related to the inaccessibility of spatial information through non-visual means.

Early blindness modulates haptic object recognition

Haptic object recognition is usually an efficient process although slower and less accurate than its visual counterpart. The early loss of vision imposes a greater reliance on haptic perception for recognition compared to the sighted. Therefore, we may expect that congenitally blind persons could recognize objects through touch more quickly and accurately than late blind or sighted people. However, the literature provided mixed results. Furthermore, most of the studies on haptic object recognition focused on performance, devoting little attention to the exploration procedures that conducted to that performance. In this study, we used iCube, an instrumented cube recording its orientation in space as well as the location of the points of contact on its faces. Three groups of congenitally blind, late blind and age and gender-matched blindfolded sighted participants were asked to explore the cube faces where little pins were positioned in varying number. Participants were required to explore the cube twice, reporting whether the cube was the same or it differed in pins disposition. Results showed that recognition accuracy was not modulated by the level of visual ability. However, congenitally blind touched more cells simultaneously while exploring the faces and changed more the pattern of touched cells from one recording sample to the next than late blind and sighted. Furthermore, the number of simultaneously touched cells negatively correlated with exploration duration. These findings indicate that early blindness shapes haptic exploration of objects that can be held in hands.

Communicating Photograph Content Through Tactile Images to People With Visual Impairments

Millions of people with a visual impairment across the world are denied access to visual images. They are unable to enjoy the simple pleasures of viewing family photographs, those in textbooks or tourist brochures and the pictorial embellishment of news stories etc. We propose a simple, inexpensive but effective approach, to make content accessible via touch. We use state-of-the-art algorithms to automatically process an input photograph into a collage of icons, that depict the most important semantic aspects of a scene. This collage is then printed onto swell paper. Our experiments show that people can recognise content with an accuracy exceeding 70% and create plausible narratives to explain it. This means that people can understand image content via touch. Communicating scene foreground is a step forward, but there are many other steps needed to provide the visually impaired with the fullest possible access to visual content.

Do blind people share the tall-man stereotype?

The stereotype of a tall man has been reported in numerous studies. High stature is commonly associated with advantages such as leadership skills, wealth, intelligence or social status, and actual differences between the short and the tall men were indeed found for these traits, mainly in favor of the tall men. It is not certain, however, whether the height-related effects are biologically determined or if they result from socially-driven mechanisms. In this study we wanted to explore whether congenitally blind individuals, who are unable to perceive other people’s stature through the most salient, visual channel, share the positive, height-related stereotype. Thirty-four congenitally blind and forty-three sighted men and women rated four positive characteristics of a tall or a short man. It was found that none of the traits assigned to the tall man by the sighted people was assigned to this person by the blind individuals. In the congenitally blind group, no differences between the assessments of the tall and the short man were revealed. We discuss our findings in the context of social perception and stereotypes research.

A Study of Multi-Sensory Experience and Color Recognition in Visual Arts Appreciation of People with Visual Impairment

Visually impaired visitors experience many limitations when visiting museum exhibits, such as a lack of cognitive and sensory access to exhibits or replicas. Contemporary art is evolving in the direction of appreciation beyond simply looking at works, and the development of various sensory technologies has had a great influence on culture and art. Thus, opportunities for people with visual impairments to appreciate visual artworks through various senses such as hearing, touch, and smell are expanding. However, it is uncommon to provide an interactive interface for color recognition, such as applying patterns, sounds, temperature, or scents. This review aims to convey the visual elements of the work to the visually impaired through various sensory elements. In addition, to open a new perspective on appreciation of the works, the technique of expressing the color coded by integrating patterns, temperature, scent, music, and vibration was explored, and future research topics were presented.

Exploring 3D miniatures with action simulations by finger gestures: Study of a new embodied design for blind and sighted children

Tactile books for blind children generally contain tactile illustrations referring to a visual world that can be difficult to understand. This study investigates an innovative way to present content to be explored by touch. Following embodied approaches and evidence about the advantages of manipulations in tactile processing, we examined 3D miniatures that children explored using their middle and index fingers to simulate leg movements. This “Action simulations by finger gestures–ASFG” procedure has a symbolic relevance in the context of blindness. The aim of the present study was to show how the ASFG procedure facilitates the identification of objects by blind and sighted children. Experiment 1 examined the identification of 3D miniatures of action objects (e.g. the toboggan, trampoline) by 8 early blind and 15 sighted children, aged 7 to 12, who explored with the ASFG procedure. Results revealed that objects were very well identified by the two groups of children. Results confirmed hypotheses that ASFG procedures are relevant in the identification process regardless of the visual status of subjects. Experiment (control) 2 studied identification of tactile pictures of same action objects by 8 different early blind and 15 sighted children, aged 7 to 12. Results confirmed that almost all objects obtained lower recognition scores in tactile pictures than in 3D miniatures by both groups and showed surprisingly higher scores in blind children than in sighted children. Taken together, our study provides evidence of the contribution of sensorimotor simulation in the identification of objects by touch and brings innovative solutions in book design for blind people. Moreover, it means that only the ASFG procedure has a very inclusive potential to be relevant for a larger number of subjects, regardless of their visual skills.

Active sensory substitution allows fast learning via effective motor-sensory strategies

We examined the development of new sensing abilities in adults by training participants to perceive remote objects through their fingers. Using an Active-Sensing based sensory Substitution device (ASenSub), participants quickly learned to perceive fast via the new modality and preserved their high performance for more than 20 months. Both sighted and blind participants exhibited almost complete transfer of performance from 2D images to novel 3D physical objects. Perceptual accuracy and speed using the ASenSub were, on average, 300% and 600% better than previous reports for 2D images and 3D objects. This improvement is attributed to the ability of the participants to employ their own motor-sensory strategies. Sighted participants dominant strategy was based on motor-sensory convergence on the most informative regions of objects, similarly to fixation patterns in vision. Congenitally, blind participants did not show such a tendency, and many of their exploratory procedures resembled those observed with natural touch.

Using a ripple wall to help blind people measure the water level in a container

The aim of this study is to determine whether swiping the ripple wall of a container can help blind people to measure the water level in it. Swiping the ripples on the wall of a container above the water level produces a different sound from doing so below the water level, and this difference in sound may be able to indicate the level of water in the container. Such sound differences associated with 27 3 D-printed containers with a capacity of 500 ml and various forms were recorded. One of the printed containers and a commercially available beverage container were tested by blind people to measure water levels in three operations. The experimental results reveal that the thickness of the wall affected the sound most strongly. The errors in the estimated water levels were significantly smaller when the containers was lifted and swiped than when it was lifted only. Practitioner summary: Lifting only is used by blind people to judge the fullness of a container. The experimental results reveal that the errors in the estimated water levels were significantly smaller when blind people lifted and swiped a 500 ml container with a ripple wall than when it was lifted only. Abbreviations: FA I: fast adapting fibers I; FA II: fast adapting fibers II; SA I: slowly adapting fibers I; SA II: slowly adapting fibers II.

Identification of Textured Tactile Pictures in Visually Impaired and Blindfolded Sighted Children

A high level of variability in the capacity of visually impaired children to accurately identify tactile images is reported in the literature, with on average rather low percentages of correct naming responses. However, most of these studies used raised-line drawings as stimuli to be explored and named. The present experiment investigated whether blind children of 3 to 8 years of age would demonstrate a satisfactory ability to name the elements making up tactile images when tested in an experimental setting similar to their natural reading conditions. Textured tactile images taken from genuine illustrated tactile books for young children were used, and the participants received information about the title of the book or listened the text that accompanied each picture before exploration, as it would occur in a natural reading setting. The results showed that their naming scores were indeed higher than previously reported at equivalent ages and did not differ from those of age-matched sighted children. These scores were positively impacted by haptic practice in blind children and correlated with the use of some specific exploratory procedures. The blind children benefited from information provided before exploration, as did their sighted counterparts. However, only in the former did the condition in which full information was provided influence the way the children organized their exploration. The haptic identification scores increased with age regardless of visual status, with the exploration times decreasing in the blind children, while the reverse trend was observed in the sighted children. These results are discussed at the light of the image-mediation model of haptics, suggesting that during the age period considered in the present experiment, blind children would progressively learn to process haptic information directly, thus leading to a decrease of exploration times, while sighted children would learn to translate haptic information into a visual image used to retrieve semantic information, involving an increase of their exploration times.

Improved access to museum collections without vision: How museum visitors with very low or no vision perceive and process tactile–auditory pictures

This study investigated how museum visitors with very low or no vision perceived and processed tactile pictures and/or audio-descriptions of visual paintings. Two visual paintings were selected and a focus group was established ( N = 8). Qualitative interview and observation data were collected. This study found two types of museum visitors: those who explored the tactile picture first and those who rather listened to the audio-description. When exploring each element in the tactile picture, they all started by exploring the element’s global (shape) outline and, when struggling to recognise it, turned to the audio-description. They preferred the audio-description to start describing where their fingers were. Tactile texture attracted their attention, sparked their curiosity, and enabled them to create a mental image of the tactile picture, but also confused them. They preferred the global (element shape) outline to be straightened out, so that curves become angular, and texture only for targeting certain elements.

Enhancing general spatial skills of young visually impaired people with a programmable distance discrimination training: a case control study

BACKGROUND

The estimation of relative distance is a perceptual task used extensively in everyday life. This important skill suffers from biases that may be more pronounced when estimation is based on haptics. This is especially true for the blind and visually impaired, for which haptic estimation of distances is paramount but not systematically trained. We investigated whether a programmable tactile display, used autonomously, can improve distance discrimination ability in blind and severely visually impaired youngsters between 7 and 22 years-old.

METHODS

Training consisted of four weekly sessions in which participants were asked to haptically find, on the programmable tactile display, the pairs of squares which were separated by the shortest and longest distance in tactile images with multiple squares. A battery of haptic tests with raised-line drawings was administered before and after training, and scores were compared to those of a control group that did only the haptic battery, without doing the distance discrimination training on the tactile display.

RESULTS

Both blind and severely impaired youngsters became more accurate and faster at the task during training. In haptic battery results, blind and severely impaired youngsters who used the programmable display improved in three and two tests, respectively. In contrast, in the control groups, the blind control group improved in only one test, and the severely visually impaired in no tests.

CONCLUSIONS

Distance discrimination skills can be trained equally well in both blind and severely impaired participants. More importantly, autonomous training with the programmable tactile display had generalized effects beyond the trained task. Participants improved not only in the size discrimination test but also in memory span tests. Our study shows that tactile stimulation training that requires minimal human assistance can effectively improve generic spatial skills.

Weight-Discrimination Sensitivity in Congenitally Blind and Sighted Adults

This study compared the weight-discrimination sensitivity of 41 congenitally blind and 41 normally sighted adults. The superior weight-discrimination sensitivity of the congenitally blind subjects suggests that blindness from birth can cause compensatory adaptations within the cutaneous modality.

The Effects of Visual Experience and Training in Raised-Line Materials on the Mental Spatial Imagery of Blind Persons

Visual experience improved performances of blind adults in mental rotation and mental representation of the path of a spot. Congenitally blind participants with high expertise in graphic material performed better than two categories of nonexpert participants—those who became blind early in their lives versus those who became blind later in their lives—indicating that graphic expertise may compensate for the lack of visual representations. Implications for teaching are discussed.

Adults' visual recognition of actions simulations by finger gestures (ASFGs) produced by sighted and blind individuals

The present study examines the visual recognition of action simulations by finger gestures (ASFGs) produced by sighted and blind individuals. In ASFGs, fingers simulate legs to represent actions such as jumping, spinning, climbing, etc. The question is to determine whether the common motor experience of one’s own body is sufficient to produce adequate ASFGs or whether the possibility to see gestures from others are also necessary to do it. Three experiments were carried out to address this question. Experiment 1 examined in 74 sighted adults the recognition of 18 types of ASFGs produced by 20 blindfolded sighted adults. Results showed that rates of correct recognition were globally very high, but varied with the type of ASFG. Experiment 2 studied in 91 other sighted adults the recognition of ASFGs produced by 10 early blind and 7 late blind adults. Results also showed a high level of recognition with a similar order of recognizability by type of ASFG. However, ASFGs produced by early blind individuals were more poorly recognized than those produced by late blind individuals. In order to match data of recognition obtained with the form that gestures are produced by individuals, two independant judges evaluated prototypical and atypical attributes of ASFG produced by blindfolded sighted, early blind and late blind individuals in Experiment 3. Results revealed the occurrence of more atypical attributes in ASFG produced by blind individuals: their ASFGs transpose more body movements from a character-viewpoint in less agreement with visual rules. The practical interest of the study relates to the relevance of including ASFGs as a new exploratory procedure in tactile devices which are more apt to convey action concepts to blind users/readers.

Comparing the Effects of Congenital and Late Visual Impairments on Visuospatial Mental Abilities

This study compared participants who were congenitally visually impaired and those who became visually impaired later in life in a spatial memory task. The latter showed less efficient visuospatial processes than did the former. However, these differences were of a quantitative nature only, indicating common cognitive mechanisms that can be clearly differentiated from those of people who are congenitally blind.

The severity of the visual impairment and practice matter for drawing ability in children

BACKGROUND AND AIMS

Astonishing drawing capacities have been reported in children with early visual impairments. However, most of the evidence relies on single case studies. Hitherto, no study has systematically jointly investigated, in these children, the role of (1) the severity of the visual handicap, (2) age and (3) practice in drawing. The study aimed at revealing the specificities of the drawing in children deprived from vision, as compared to children with less severe visual handicap and to sighted children performing under haptic or usual visual control.

METHOD

148 children aged 6-14 years had to produce 12 drawings of familiar objects. 38 had a severe visual impairment, 41 suffered from low vision, and 69 were sighted children performing either under visual condition or blindfolded under haptic control.

RESULTS

Recognizability and other characteristics of the drawings were highly dependent on the child's degree of vision and level of drawing practice, and progressed with chronological age more clearly in the sighted children or those with low vision than in those deprived of vision.

CONCLUSION

The study confirmed that all groups showed significant drawing ability, even the group totally deprived of visual experience. Furthermore, the specificities of the drawings produced by visually-impaired children appeared clearly related to their practice and the severity of their visual impairment. This should incite parents and professionals to encourage these children to practice drawing as early as possible.

Bouba or kiki with and without vision: Shape-audio regularities and mental images

95% of the world's population associate a rounded visual shape with the spoken word 'bouba', and an angular visual shape with the spoken word 'kiki', known as the bouba/kiki-effect. The bouba/kiki-effect occurs irrespective of familiarity with either the shape or word. This study investigated the bouba/kiki-effect when using haptic touch instead of vision, including the role of visual imagery. It also investigated whether the bouba/kiki shape-audio regularities are noticed at all, that is, whether they affect the bouba/kiki-effect itself and/or the recognition of individual bouba/kiki shapes, and finally what mental images they produce. Three experiments were conducted, with three groups of participants: blind, blindfold, and vision. In Experiment 1, the participants were asked to pick out the tactile/visual shape that they associated with the auditory bouba/kiki. Experiment 1 found that the participants who were blind did not show an instant bouba/kiki-effect (in Trial 1), whereas the blindfolded and the fully sighted did. It also found that the bouba/kiki shape-audio regularities affected the bouba/kiki-effect when using haptic touch: Those who were blind did show the bouba/kiki-effect from Trial 4, and those who were blindfolded no longer did. In Experiment 2, the participants were asked to name one tactile/visual shape and a segment of audio together as either 'bouba' or 'kiki'. Experiment 2 found that corresponding shape and audio improved the accuracy of both the blindfolded and the fully sighted, but not of those who were blind - they ignored the audio. Finally, in Experiment 3, the participants were asked to draw the shape that they associated with the auditory bouba/kiki. Experiment 3 found that their mental images, as depicted in their drawings, were not affected by whether they had experienced the bouba/kiki shapes by haptic touch or by vision. Regardless of their prior shape experience, that is, tactile or visual, their mental images included the most characteristic shape feature of bouba and kiki: curve and angle, respectively, and typically not the global shape. When taken together, these experiments suggest that the sensory regularities and mental images concerning bouba and kiki do not have to be based on, or even include visual information.

The Effect of Programmable Tactile Displays on Spatial Learning Skills in Children and Adolescents of Different Visual Disability

Vision loss has severe impacts on physical, social and emotional well-being. The education of blind children poses issues as many scholar disciplines (e.g., geometry, mathematics) are normally taught by heavily relying on vision. Touch-based assistive technologies are potential tools to provide graphical contents to blind users, improving learning possibilities and social inclusion. Raised-lines drawings are still the golden standard, but stimuli cannot be reconfigured or adapted and the blind person constantly requires assistance. Although much research concerns technological development, little work concerned the assessment of programmable tactile graphics, in educative and rehabilitative contexts. Here we designed, on programmable tactile displays, tests aimed at assessing spatial memory skills and shapes recognition abilities. Tests involved a group of blind and a group of low vision children and adolescents in a four-week longitudinal schedule. After establishing subject-specific difficulty levels, we observed a significant enhancement of performance across sessions and for both groups. Learning effects were comparable to raised paper control tests: however, our setup required minimal external assistance. Overall, our results demonstrate that programmable maps are an effective way to display graphical contents in educative/rehabilitative contexts. They can be at least as effective as traditional paper tests yet providing superior flexibility and versatility.

Obstacles to Testing Molyneux's Question Empirically

There have recently been various empirical attempts to answer Molyneux’s question, for example, the experiments undertaken by the Held group. These studies, though intricate, have encountered some objections, for instance, from Schwenkler, who proposes two ways of improving the experiments. One is “to re-run [the] experiment with the stimulus objects made to move, and/or the subjects moved or permitted to move with respect to them” (p. 94), which would promote three dimensional or otherwise viewpoint-invariant representations. The other is “to use geometrically simpler shapes, such as the cube and sphere in Molyneux’s original proposal, or planar figures instead of three-dimensional solids” (p. 188). Connolly argues against the first modification but agrees with the second. In this article, I argue that the second modification is also problematic (though still surmountable), and that both Schwenkler and Connolly are too optimistic about the prospect of addressing Molyneux’s question empirically.

Beyond visual conventions: Rethinking the design of tactile diagrams

This article reviews the debate over the comprehension of two-dimensional microcapsule tactile pictures portraying three-dimensional information through the use of perspective and visual drawing conventions. It is proposed that three-dimensional haptic object recognition and its relationship to visual object recognition can inform the design of two-dimensional tactual displays. Experimental work is discussed which validates the use of such information in informing the design of 2-D tactile pictures.

Angle Discrimination in Raised-Line Drawings

We investigated the angular resolution subserving the haptic perception of raised-line drawings by measuring how accurately observers could discriminate between two angle sizes under various conditions. We found that, for acute angles, discrimination performance is highly dependent on exploration strategy: mean thresholds of 2.9° and 6.0° were found for two different exploration strategies. For one of the strategies we found that discriminability is not dependent on the bisector orientation of the angle. Furthermore, we found that thresholds almost double when the angular extent is increased from 20° to 135°. We also found that local apex information has a significant influence on discrimination for acute as well as obtuse angles. In the last experiment we investigated the influence of depiction mode but did not find any effect. Overall, the results tell us that the acuity with which angles in raised-line drawings are perceived is determined by the exploration strategy, local apex information, and global angular extent.

Haptic Pictures: Fit Judgments Predict Identification, Recognition Memory, and Confidence

D'Angiulli et al (1998 Scandinavian Journal of Psychology39 187–190) found blind and sighted (blindfolded) children identified common objects in raised-outline drawings explored haptically, and corrected themselves without feedback. The self-correction suggests that participants can assess the extent to which the referents they suggest as possible identifications fit the haptic pictures. Indeed, when we asked subjects to identify haptic pictures, and to judge how well the referents they mentioned fitted the pictures, their fit judgments predicted the accuracy of their suggestions. Also, when one group of subjects offered the suggestions and another group assessed the fit of the suggestions to the pictures, the fit judgments predicted the accuracy of the suggestions. Further, good fit predicted successful recognition memory. In addition, both high and low fit judgments were made confidently, so the range of confidence judgments was smaller than the range of fit judgments. Finally, visual judgments of fit by one group predicted the level of success of the suggestions from another (haptic) group. In sum, subjects assess their suggested identifications appropriately, most likely on the basis of object shape criteria, outlined surface edges, and use of a vantage point.

Simultaneous Sketching Aids the Haptic Identification of Raised Line Drawings

Haptically identifying raised line drawings is difficult. We investigated whether a major component of this difficulty lies in acquiring, integrating, and maintaining shape information from touch. Wijntjes, van Lienen, Verstijnen, and Kappers reported that drawings which participants had failed to identify by touch alone could often subsequently be named if they were sketched. Thus, people sometimes needed to externalize haptically acquired information by making a sketch in order to be able to use it. We extended Wijntjes et al.'s task and found that sketching while touching improved drawing identification even more than sketching after touching, but only if people could see their sketches. Our results suggest that the slow, serial nature of information acquisition seriously hampers the haptic identification of raised line drawings relative to visually identifying line drawings. Simultaneous sketching may aid identification by reducing the burden on working memory and by helping to guide haptic exploration. This conclusion is consistent with the finding reported by Lawson and Bracken that 3-D objects are much easier to identify haptically than raised line drawings since, unlike for vision, simultaneously extracting global shape information is much easier haptically for 3-D stimuli than for line drawings.

Designing Haptic Assistive Technology for Individuals Who Are Blind or Visually Impaired

This paper considers issues relevant for the design and use of haptic technology for assistive devices for individuals who are blind or visually impaired in some of the major areas of importance: Braille reading, tactile graphics, orientation and mobility. We show that there is a wealth of behavioral research that is highly applicable to assistive technology design. In a few cases, conclusions from behavioral experiments have been directly applied to design with positive results. Differences in brain organization and performance capabilities between individuals who are "early blind" and "late blind" from using the same tactile/haptic accommodations, such as the use of Braille, suggest the importance of training and assessing these groups individually. Practical restrictions on device design, such as performance limitations of the technology and cost, raise questions as to which aspects of these restrictions are truly important to overcome to achieve high performance. In general, this raises the question of what it means to provide functional equivalence as opposed to sensory equivalence.

Tactile search for change has less memory than visual search for change

Haptic perception of a 2D image is thought to make heavy demands on working memory. During active exploration, humans need to store the latest local sensory information and integrate it with kinesthetic information from hand and finger locations in order to generate a coherent perception. This tactile integration has not been studied as extensively as visual shape integration. In the current study, we compared working-memory capacity for tactile exploration to that of visual exploration as measured in change-detection tasks. We found smaller memory capacity during tactile exploration (approximately 1 item) compared with visual exploration (2-10 items). These differences generalized to position memory and could not be attributed to insufficient stimulus-exposure durations, acuity differences between modalities, or uncertainty over the position of items. This low capacity for tactile memory suggests that the haptic system is almost amnesic when outside the fingertips and that there is little or no cross-position integration.

Perception of tactile graphics: embossings versus cutouts

Graphical information, such as illustrations, graphs, and diagrams, are an essential complement to text for conveying knowledge about the world. Although graphics can be communicated well via the visual modality, conveying this information via touch has proven to be challenging. The lack of easily comprehensible tactile graphics poses a problem for the blind. In this paper, we advance a hypothesis for the limited effectiveness of tactile graphics. The hypothesis contends that conventional graphics that rely upon embossings on two-dimensional surfaces do not allow the deployment of tactile exploratory procedures that are crucial for assessing global shape. Besides potentially accounting for some of the shortcomings of current approaches, this hypothesis also serves a prescriptive purpose by suggesting a different strategy for conveying graphical information via touch, one based on cutouts. We describe experiments demonstrating the greater effectiveness of this approach for conveying shape and identity information. These results hold the potential for creating more comprehensible tactile drawings for the visually impaired while also providing insights into shape estimation processes in the tactile modality.

Neural correlates associated with superior tactile symmetry perception in the early blind

Symmetry is an organizational principle that is ubiquitous throughout the visual world. However, this property can also be detected through non-visual modalities such as touch. The role of prior visual experience on detecting tactile patterns containing symmetry remains unclear. We compared the behavioral performance of early blind and sighted (blindfolded) controls on a tactile symmetry detection task. The tactile patterns used were similar in design and complexity as in previous visual perceptual studies. The neural correlates associated with this behavioral task were identified with functional magnetic resonance imaging (fMRI). In line with growing evidence demonstrating enhanced tactile processing abilities in the blind, we found that early blind individuals showed significantly superior performance in detecting tactile symmetric patterns compared to sighted controls. Furthermore, comparing patterns of activation between these two groups identified common areas of activation (e.g. superior parietal cortex) but key differences also emerged. In particular, tactile symmetry detection in the early blind was also associated with activation that included peri-calcarine cortex, lateral occipital (LO), and middle temporal (MT) cortex, as well as inferior temporal and fusiform cortex. These results contribute to the growing evidence supporting superior behavioral abilities in the blind, and the neural correlates associated with crossmodal neuroplasticity following visual deprivation.

Effects of using multiple hands and fingers on haptic performance in individuals who are blind

In a previous paper we documented that sighted participants complete haptic tasks faster with two hands and multiple fingers, but that these benefits are task specific. The present study investigates whether these effects are the same for participants who are blind. We compared the performance of fourteen blind participants on seven tactile-map tasks using seven finger conditions. As with sighted participants, blind participants performed all tasks faster with multiple fingers. Line-tracing tasks were faster with fingers added to an already in-use hand, and sometimes when added to the second hand. Local and global search tasks were faster with multiple fingers and two hands. Distance comparison tasks were performed faster with multiple fingers, but not two hands. Lastly, moving in a straight line was faster with multiple fingers. These results reinforce our previous finding that the haptic system performs best when it can exploit the independence of multiple fingers. Furthermore, in every instance that an effect was different between sighted and blind participants, the blind participants benefitted more from two hands or multiple fingers than the sighted participants. This indicates that the blind participants have learned, through experience or training, how to best take advantage of multiple fingers during haptic tasks.

Compensatory plasticity: time matters

Plasticity in the human and animal brain is the rule, the base for development, and the way to deal effectively with the environment for making the most efficient use of all the senses. When the brain is deprived of one sensory modality, plasticity becomes compensatory: the exception that invalidates the general loss hypothesis giving the opportunity of effective change. Sensory deprivation comes with massive alterations in brain structure and function, behavioral outcomes, and neural interactions. Blind individuals do as good as the sighted and even more, show superior abilities in auditory, tactile and olfactory processing. This behavioral enhancement is accompanied with changes in occipital cortex function, where visual areas at different levels become responsive to non-visual information. The intact senses are in general used more efficiently in the blind but are also used more exclusively. New findings are disentangling these two aspects of compensatory plasticity. What is due to visual deprivation and what is dependent on the extended use of spared modalities? The latter seems to contribute highly to compensatory changes in the congenitally blind. Short-term deprivation through the use of blindfolds shows that cortical excitability of the visual cortex is likely to show rapid modulatory changes after few minutes of light deprivation and therefore changes are possible in adulthood. However, reorganization remains more pronounced in the congenitally blind. Cortico-cortical pathways between visual areas and the areas of preserved sensory modalities are inhibited in the presence of vision, but are unmasked after loss of vision or blindfolding as a mechanism likely to drive cross-modal information to the deafferented visual cortex. The development of specialized higher order visual pathways independently from early sensory experience is likely to preserve their function and switch to the intact modalities. Plasticity in the blind is also accompanied with neurochemical and morphological changes; both intrinsic connectivity and functional coupling at rest are altered but are likewise dependent on different sensory experience and training.

The effect of vertical and horizontal symmetry on memory for tactile patterns in late blind individuals

Visual stimuli that exhibit vertical symmetry are easier to remember than stimuli symmetric along other axes, an advantage that extends to the haptic modality as well. Critically, the vertical symmetry memory advantage has not been found in early blind individuals, despite their overall superior memory, as compared with sighted individuals, and the presence of an overall advantage for identifying symmetric over asymmetric patterns. The absence of the vertical axis memory advantage in the early blind may depend on their total lack of visual experience or on the effect of prolonged visual deprivation. To disentangle this issue, in this study, we measured the ability of late blind individuals to remember tactile spatial patterns that were either vertically or horizontally symmetric or asymmetric. Late blind participants showed better memory performance for symmetric patterns. An additional advantage for the vertical axis of symmetry over the horizontal one was reported, but only for patterns presented in the frontal plane. In the horizontal plane, no difference was observed between vertical and horizontal symmetric patterns, due to the latter being recalled particularly well. These results are discussed in terms of the influence of the spatial reference frame adopted during exploration. Overall, our data suggest that prior visual experience is sufficient to drive the vertical symmetry memory advantage, at least when an external reference frame based on geocentric cues (i.e., gravity) is adopted.

Haptic spatial configuration learning in deaf and hearing individuals

The present study investigated haptic spatial configuration learning in deaf individuals, hearing sign language interpreters and hearing controls. In three trials, participants had to match ten shapes haptically to the cut-outs in a board as fast as possible. Deaf and hearing sign language users outperformed the hearing controls. A similar difference was observed for a rotated version of the board. The groups did not differ, however, on a free relocation trial. Though a significant sign language experience advantage was observed, comparison to results from a previous study testing the same task in a group of blind individuals showed it to be smaller than the advantage observed for the blind group. These results are discussed in terms of how sign language experience and sensory deprivation benefit haptic spatial configuration processing.

Exploratory procedures of tactile images in visually impaired and blindfolded sighted children: how they relate to their consequent performance in drawing

The aim of the present study was to compare the types of exploratory procedures employed by children when exploring bidimensional tactile patterns and correlate the use of these procedures with the children's shape drawing performance. 18 early blind children, 20 children with low vision and 24 age-matched blindfolded sighted children aged approximately 7 or 11 years were included in the study. The children with a visual handicap outperformed the sighted children in terms of haptic exploration and did not produce less recognizable drawings than their sighted counterparts. Close relationships were identified between the types of exploratory procedures employed by the children and their subsequent drawing performance, regardless of visual status. This close link between action and perception in the haptic modality indicates the importance of training blind children in exploratory procedures at an early age.

Representing users in accessibility research

The need to study representative users is widely accepted within the human-computer interaction (HCI) community. While exceptions exist, and alternative populations are sometimes studied, virtually any introduction to the process of designing user interfaces will discuss the importance of understanding the intended users as well as the significant impact individual differences can have on how effectively individuals can use various technologies. HCI researchers are expected to provide relevant demographics regarding study participants as well as information about experience using similar technologies. Yet in the field of accessibility, we continue to see studies that do not appropriately include representative users. Highlighting ways to remedy this multifaceted problem, we argue that expectations regarding how accessibility research is conducted and reported must be raised if this field is to have the desired impact with regard to inclusive design, the information technologies studied, and the lives of the individuals studied.

The role of visual experience for the neural basis of spatial cognition

Blindness often results in the adaptive neural reorganization of the remaining modalities, producing sharper auditory and haptic behavioral performance. Yet, non-visual modalities might not be able to fully compensate for the lack of visual experience as in the case of congenital blindness. For example, developmental visual experience seems to be necessary for the maturation of multisensory neurons for spatial tasks. Additionally, the ability of vision to convey information in parallel might be taken into account as the main attribute that cannot be fully compensated by the spared modalities. Therefore, the lack of visual experience might impair all spatial tasks that require the integration of inputs from different modalities, such as having to represent a set of objects on the basis of the spatial relationships among the objects, rather than the spatial relationship that each object has with oneself. Here we integrate behavioral and neural evidence to conclude that visual experience is necessary for the neural development of normal spatial cognition.

The impact of vision in spatial coding

The aim of this study is to examine the performance in coding and representing of near-space in relation to vision status (blindness vs. normal vision) and sensory modality (touch vs. vision). Forty-eight children and teenagers participated. Sixteen of the participants were totally blind or had only light perception, 16 were blindfolded sighted individuals, and 16 were non-blindfolded sighted individuals. Participants were given eight different object patterns in different arrays and were asked to code and represent each of them. The results suggest that vision influences performance in spatial coding and spatial representation of near space. However, there was no statistically significant difference between participants with blindness who used the most effective haptic strategy and blindfolded sighted participants. Thus, the significance of haptic strategies is highlighted.

Piaget's water-level task: the impact of vision on performance

In the present study, the aim was to examine the differences in performance between children and adolescents with visual impairment and sighted peers in the water-level task. Twenty-eight individuals with visual impairments, 14 individuals with blindness and 14 individuals with low vision, and 28 sighted individuals participated in the present study. Fourteen sighted individuals participated blindfolded and 14 were able to use their sight. The findings indicate that use of vision can influence the performance in water-level task. However, in the restriction of visual ability (participants with blindfold), individuals with blindness might present better performance than blindfolded sighted participants.