Influence of visual guidance on braille recognition Low

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676 HELLER, a six dot matrix Braille patterns have few internal fea folded helped her generate visual images of the tactile. tures that could serve as spatial anchor points Millar has maps In addition educators of the visually impaired have. suggested that higher order as well as low order cogni been known to blindfold people with low vision to facili. tive skills are involved in braille reading which is very tate instruction in mobility skills Lauren 1988. difficult for the novice Observation of subject behavior. shows that a variety of clumsy scrubbing behaviors Method. are frequent in new braille readers Skilled readers rarely Subjects There were 48 sighted subjects 28 females and 20. engage in scrubbing and show smooth lateral scan males recruited from an undergraduate population All observers. ning of lines of braille also see Foulke 1991 were unfamiliar with braille. Stimuli and Apparatus The stimuli were standard braille charac. The present research was designed to gather further in ters representing the letters B J The patterns were embossed on. formation about the precise nature of the visual informa plastic cards obtained from the American Foundation for the Blind. tion that was responsible for the previously reported VG Standard braille uses a 3 x 2 matrix of dots and is about 6 mm. effect on braille recognition As in prior research dark high the letters B J are only about 4 mm high The braille pat. ness LEDs and stained glass were used to manipulate terns were all tilted 90 from the upright The stimuli were ar. visual information about tactual exploration Control sub ranged randomly in five horizontal rows with five characters in. each row A final row contained two braille patterns The begin. jects examined braille without VG in normal room light. ning and end of each line of braille were marked by thumbtacks. ing or in relative darkness Heller 1989b 1992a pushed into the braille paper For VG subjects a box covered with. stained glass was used to permit sight of scanning movements and. EXPERIMENT 1 the LEOS while it eliminated vision of the dots and the subjects. The Effect of Visual Guidance hands see Heller 1982 1983 1985 1989b for further details. on 90 Tilted Braille In normal room lighting the stained glass allows the observer blurry. vision of his her finger but renders embossing and other material. invisible However in the VG conditions of the present experiment. This experiment was designed to determine the nature lighting was reduced and overall room lighting was limited to light. of the benefits of VG on tactual exploration VG might from three submini lamps 1 5 V 25 rnA 0 81 lx at 4 ern One. provide assistance to touch via sight of scanning move lamp was used to illuminate the drawing of the braille array for. ments Heller 1985 or through the provision of a visual visual matches the other two lights behind the Masonite baffle. frame of reference This hypothesis was suggested by the allowed the experimenter sufficient sight to keep track of the sub. damaging effects of finger tilt on braille recognition jects exploratory behavior Observers were able to see the draw. ing of the braille code the characters B J and letter equivalents. Heller 1987 Sighted individuals made visual matches as they touched the invisible tangible stimuli in the examination. to embossed braille characters that were tilted 90 from box This allowed them to verbally name the letters that cor. the upright Some observers were permitted VG of tac responded to the braille patterns that they touched. tual exploration control subjects were denied visual regu Sight of finger angle was provided via two small LEOs one placed. lation VG was accomplished by subjects viewing their on the upper surface hairy skin of the index finger middle. tactual exploration through plastic stained glass In addi phalanx and the other on the top of the fingernail of the explor. tion low lighting eliminated sight of the finger hand em atory fingertip red LEOS power dissipation of 60 mW luminous. intensity of 6 3 moo each powered by a single 1 5 V battery in. bossing and surfaces dividuals observed tactual exploration through stained glass In. One control group of subjects was tested in relative the present experiment the moderately dark adapted observers could. darkness but without VG These dark adapted subjects not see the array the thumbtacks or their fingers in relation to. had a small submini lamp above the visual matching thebackground The subjects were limitedto sight of scanning move. code A second group was permitted VG which consisted ments via the two LEOs and could presumably generate visual. of vision of finger angle These subjects had two small representations of these movement patterns see Heller 1985 In. addition LEOs were used to provide a blurry line of light above. LEOs attached to the upper surface of the finger see the lines of braille in another condition and a second pair of LEOs. Heller 1989b Another group was given visual infor allowed the subjects vision of the angle of the finger. mation about both the angle of the exploratory finger via Design and Procedure The experiment was an independent. two LEOs and the angle of the lines of braille that is group one way analysis of variance The factor was the presence. visual spatial reference information These subjects also or absence of VO and the nature of visual information provided. had a line of LEOs above each line of braille A control with all tangible symbols tilted at 900 from the upright A stop. watch was used to time the subjects on each line of braille The. group examined the braille with normal room lighting. subjects were given verbal guidance if they strayed from lines of. The low light control group was included to determine braille or lost their place but no other feedback was given Prior. whether irrelevant visual stimulation from the experimen to the experiment the observers were shown a familiarization card. tal environment could interfere with the subjects mental with the embossed braille code that represented the letters A J. rotation of visual representations of haptic input This Exploration was limited to the tip of the index finger of the writ. low light condition was suggested by observation of the ing hand All reading was from left to right and the VG sub. behavior of some individuals in normal bimodal ex jects were told to observe the LEOS on their fingers as they touched. the braille The subjects were told that the tangible patterns were. perimental conditions in past research Some subjects tilted 90 In addition a line drawing representing the orientation. seemed to avert their gaze as they touched textures or pat of thebraille was present throughout as was a drawing of the braille. terns in prior research A subject in an ongoing map study code with its letter equivalents The observers made visual matches. reported that closing her eyes even while she was blind to the tangible code and verbally named the patterns they touched. VISUAL GUIDANCE OF TOUCH 677, In one control condition the subjects were tested in the dark What do we make of the superior performance of the. with a small light above the braille code The top of the braille box group in low lighting The low light group did as well. was covered with an opaque material for the groups that were not as the spatial reference VG group One possibility of. allowed visual guidance In another group the subjects looked. course is that low lighting simply helps subjects attend. through stained glass as they touched the braille and viewed two. LEOs on the top of the preferred exploratory index finger the sec to tactile input Another hypothesis is that low light helps. ond LEO was placed between the two middle index finger joints subjects engage in mental rotation of visual images as they. medial phalanx This allowed vision of finger angle as these sub feel the braille This assumes that irrelevant visual infor. jects explored the braille 2 LEO VG A further group of sub mation in the experimental environment may compete with. jects had two LEOS on their fingers but also had a line of five resources required for mental manipulation of visual im. LEOs above each line of braille This gave the subjects visual frame. agery of tactile input The second experiment was de. of reference information and provided sight of the finger s angle. in relation to vision of the angle of the lines of braille It should. signed to decide between these alternative explanations. be noted that the line of five LEOs appeared as one long blurry of the effect of low lighting. red line when viewed through the stained glass cover of the box It should be remarked that this analysis does not mean. In both LEO VG conditions the subjects were unable to see either that VG has no effect beyond the attentional consequences. their fingers or the surface they touched An additional group of of low lighting It aided subjects with normal lighting. subjects touched the braille in normal room lighting 168 Ix at the in pattern identification of tilted and upright braille In. table surface as in past research on orientation Heller 1987. addition VG helped subjects avoid getting lost while. scanning lines of braille Heller 1985 1989b It is im. Results and Discussion portant to note that the VG effect was obtained for both. The results show a large effect of the nature of visual tilted and upright braille under conditions of normal room. guidance see Table 1 A simple analysis of variance on lighting Heller 1989b It should be remarked that in. the number correct showed a significant effect of visual prior demonstrations of the benefits ofVG subjects were. information F 3 44 4 3 p 01 A Newman Keuls able to see both the angles of their exploratory fingers. test on mean number correct indicated that the dark con and blue lines underneath the lines of braille. trol was not significantly different from the spatial. reference VG condition p 05 but both were superior EXPERIMENT 2. to the nonnallight control mean and the 2 LED VG group Low Versus Normal Room Lighting. p 05 The normal light group mean and the 2 and Braille Words. LED VG mean were not significantly different p, 05 The effect ofVG on mean time scores failed to reach Two groups of subjects were exposed to braille words. significance F 3 44 2 3 P 09 in normal lighting or low lighting If the effect of low. Providing visual information can either help or hurt hap lighting was simply attentional reduced illumination. tics depending on the nature and quality of the infonna should help subjects read two letter braille words. tion Performance with normal room lighting was like that. in prior research Heller 1989b 1992a and compara Method. Subjects The subjects were 24 experimentally naive sighted indi. ble to that in the 2 LED VG condition This means that viduals recruited from the same undergraduate population Eight blind. providing visual information on finger angle is not suffi subjects 5 congenitally blind and 3 late blind were recruited at indus. cient to aid tactile braille recognition The superior per tries of the Blind Workshops in Winston Salem and Greensboro These. fonnance of the group given informationabout finger angle subjects identified themselves as fair or good braille readers Blind volun. teers were recruited to obtain an idea of normal performance for read. and the angle of the line of braille implicates the impor ing braille words. tance of spatial reference information in tactual percep Stimuli and Apparatus The stimuli were 25 two letter words em. tion see Millar 1991 bossed in Grade I braille taken from Heller and Mitchell 1985 A. Mean Number Correct Percent Correct and Time in Seconds Per Character for. 90 Tilted Braille B J as a Function of Visual Guidance VG and Lighting. No Correct Time,Condition M SD Correct M SD,Dark 18 1 5 8 67 0 12 5 5 5. Control normal lighting 12 7 6 8 47 0 12 1 3 6,VG 2 LEOs on finger 12 8 4 5 47 4 16 7 9 5.
VG 2 LEOs on finger and line of LEOs 18 6 4 1 68 9 19 2 10 5. Normal lighting and VO Heller 1986b 17 9 5 1 66 3 19 5. Blind subjects Heller 1992a 20 3 75 2 7 3, Note Maximum score possible 27 SD standard deviation. 678 HELLER, life sized visual matching code illustrated the braille dot patterns and How then can we explain the beneficial effects on both. their letter equivalents Normal spacing was used The standard braille the spatial reference VG group and the control group. was embossed on plastic braille cards with a Perkins brailler with about. without VG but in relative darkness One might argue. 1 4 cm of horizontal spacing between words The words were arranged. in six horizontal lines with four words in each line a final line had one that the high performance of the control group with low. word The beginning and end of each line were marked by the heads lighting means that it is not necessary to provide spatial. of tacks The words were la at by do up to rna 10 is hi ho reference information for touch Given this interpretation. pa on we so my it me in no 00 go be am and of one might explain away the spatial reference VG effects. The braille stimuli were placed flat on a horizontal shelf behind a large. vertical panel The front of the panel was covered with an opaque black. in terms oflow lighting However the present results do. cloth The subjects could reach beneath the cloth to examine the braille not mean that normal VG effects can be explained solely. The only room lighting in the low light condition consisted of the three by low lighting VG. Perception amp Psychophysics 1993 54 5 675 681 Influence of visual guidance on braille recognition Low lighting also helps touch MORTON A HELLER

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