Haptic perception of the horizontal by blind and low-vision individuals.

We examined haptic perception of the horizontal in visually impaired people. Blind people (late blind and congenitally blind), persons with very low vision, and blindfolded sighted individuals felt raised-line drawings of jars at four angles. They had to demonstrate their understanding that water remains horizontal, despite jar tilt, by selecting the correct raised-line drawing given four choices. Low-vision subjects, with near perfect scores, performed significantly better than the other groups of subjects. While the late-blind and blindfolded sighted subjects performed slightly better than the congenitally blind participants, the difference between the late-blind and congenitally blind groups was nonsignificant. The performance of the congenitally blind subjects indicates that visual experience is not necessary for the development of an understanding that water level stays horizontal, given container tilt.

Arthroscopic decompression for impingement syndrome secondary to an unstable os acromiale.

PURPOSE: The purpose of this study was to examine cases of patients with impingement syndrome secondary to an unfused, unstable, os acromiale. TYPE OF STUDY: Retrospective case series. MATERIALS AND METHODS: Twelve consecutive patients (13 shoulders) presented with impingement symptoms in the presence of an os acromiale. The os acromiale, at the meso-acromion level, was seen on standard radiographs. The patients were all treated conservatively with rotator cuff strengthening, stretching, anti-inflammatory medications, and steroid injections. All patients underwent an impingement test with lidocaine, resulting in complete relief of their pain. After failure of the conservative management, the 12 patients (13 shoulders) underwent an extended arthroscopic subacromial decompression. The goal of the modified arthroscopic acromioplasty was resection of adequate bone to remove the mobile anterior acromial tip. In general, this consisted of more bony resection than the typical arthroscopic acromioplasty. Postoperatively, the patients began a rehabilitation program emphasizing early range of motion followed by isolated free-weight rotator cuff strengthening exercises. Five shoulders had a partial-thickness tear of the rotator cuff. Four involved less than 50% of the thickness of the rotator cuff. These 4 partial-thickness tears underwent arthroscopic rotator cuff debridement. One partial-thickness tear was greater than 50% and repair was performed with a mini-open deltoid-splitting technique. RESULTS: Results were evaluated using UCLA shoulder scoring. Preoperatively, the score averaged 17. The 3-month postoperative score was 27, and at 6 and 12 months, averaged 28. The final follow-up score averaged 31. There were 11 satisfactory results with UCLA scores >/=28. Two unsatisfactory results showed UCLA scores in the fair category. Full strength of the anterior deltoid and rotator cuff muscles was achieved in all patients by 6 months postoperatively as evaluated by manual muscle testing. Twelve of the 13 shoulders were rated by the patients as having a satisfactory result. All of the patients rated their cosmetic results as acceptable. There was no evidence of postoperative deltoid detachment. No patient developed pain at the pseudarthrosis point. CONCLUSIONS: Given the previously reported poor results with attempts at fusion of an unstable os acromiale and open complete excision of meso-acromial fragments, the authors conclude that an extended arthroscopic subacromial decompression results in a reasonable outcome for patients with impingement syndromes secondary to an unstable os acromiale.

Intersensory conflict between vision and touch: the response modality dominates when precise, attention-riveting judgments are required.

In four experiments, reducing lenses were used to minify vision and generate intersensory size conflicts between vision and touch. Subjects made size judgments, using either visual matching or haptic matching. In visual matching, the subjects chose from a set of visible squares that progressively increased in size. In haptic matching, the subjects selected matches from an array of tangible wooden squares. In Experiment 1, it was found that neither sense dominated when subjects exposed to an intersensory discrepancy made their size estimates by using either visual matching or haptic matching. Size judgments were nearly indentical for conflict subjects making visual or haptic matches. Thus, matching modality did not matter in Experiment 1. In Experiment 2, it was found that subjects were influenced by the sight of their hands, which led to increases in the magnitude of their size judgments. Sight of the hands produced more accurate judgments, with subjects being better able to compensate for the illusory effects of the reducing lens. In two additional experiments, it was found that when more precise judgments were required and subjects had to generate their own size estimates, the response modality dominated. Thus, vision dominated in Experiment 3, where size judgments derived from viewing a metric ruler, whereas touch dominated in Experiment 4, where subjects made size estimates with a pincers posture of their hands. It is suggested that matching procedures are inadequate for assessing intersensory dominance relations. These results qualify the position (Hershberger & Misceo, 1996) that the modality of size estimates influences the resolution of intersensory conflicts. Only when required to self-generate more precise judgments did subjects rely on one sense, either vision or touch. Thus, task and attentional requirements influence dominance relations, and vision does not invariably prevail over touch.

Perception of the horizontal and vertical in tangible displays: minimal gender differences.

A study is reported of gender differences in a haptic version of three Piagetian tests that assess understanding of Euclidian space. A raised-line drawing kit was used both for subject responses and for production of stimuli. To test understanding of the horizontal, subjects felt pictures of a jar at four tilts and were asked to draw the water line. Two methods were used to examine understanding of the vertical. First, subjects drew a hanging electrical cord and light bulb, attached to the ceiling of a bus, parked on hills of four different angles. Subsequently, subjects drew telephone poles (represented by a single line) on hills of four different angles. In the jar task, males and females showed comparable performance, both groups showing large errors. Judgments of the vertical were very similar for males and females in the bus task, but errors diminished considerably for both genders when subjects drew telephone poles on hills. It is suggested that better judgments of the vertical in the pole task probably derive from the use of body-centered spatial reference information.

Blind children recognizing tactile pictures respond like sighted children given guidance in exploration.

Theory of tactile pictures argues that untrained blind subjects can recognize raised, outline pictures. It contends the blind person's knowledge of the shapes of common objects is like that of the sighted, and the blind person's pictorial abilities use the same principles as the sighted person's. To test this theory, blind children (aged 8-13) and blindfolded age-matched sighted children were asked to identify raised-line drawings of common objects. Their performances were correlated. In addition, the blind children identified more than sighted children exploring the pictures actively, but the same number of pictures as sighted children who were given passive, guided exploration. We argue blind and sighted children use the same principles to identify the pictures, but the blind have superior exploration skills. The differences in the effects of exploration skills on recognition scores are minimized when the sighted children are given guidance, since the sighted children then have efficient contact with the displays, and the performance of the sighted and the blind is then governed by the same principles, without one group benefitting from advantages in exploration skills.

The delayed effects of phencyclidine (PCP) disrupt latent inhibition in a conditioned taste aversion paradigm.

The acute effects of a low dose of phencyclidine (PCP) and the delayed effects of a high dose of PCP on latent inhibition (LI) were assessed in a series of experiments using conditioned taste aversion paradigms. Each paradigm involved a preexposure phase in which water-deprived male rats were allowed access to either water (nonpreexposed; NPE) or 5% sucrose (preexposed; PE), followed by a conditioning phase in which animals were allowed access to sucrose and subsequently injected with the negative reinforcer lithium chloride, and a test phase in which animals were allowed access to both sucrose and water. LI was assessed by comparing the %-sucrose consumed in PE and NPE groups on the test day. The effects of low-dose PCP (2.5 mg/kg) were assessed by comparing LI in animals treated with vehicle or PCP 15 min prior to the onset of the preexposure and conditioning phases. A 4-day paradigm involved 2 days of preexposure followed by a day of conditioning and a test day. This paradigm produced comparable levels of LI in vehicle and PCP-treated animals. A 5-day extinction paradigm involved 2 days of preexposure followed by 2 days of conditioning and a test day. This paradigm abolished LI in vehicle and PCP-treated animals. A 3-day paradigm involved 1 day of preexposure followed by a day of conditioning and a test day. One day of preexposure induced a modified LI effect in both in vehicle and PCP-treated animals. The delayed effects of high dose PCP (8.6 mg/kg) were assessed by comparing LI in animals treated with vehicle or PCP 20 h prior to the onset of the preexposure and conditioning phases in the 4-day paradigm. PCP disrupted latent inhibition in this paradigm. The results are discussed in the context of their relevance to the ability for PCP to model schizophrenic symptomatology.

Can patents deter innovation? The anticommons in biomedical research.

The "tragedy of the commons" metaphor helps explain why people overuse shared resources. However, the recent proliferation of intellectual property rights in biomedical research suggests a different tragedy, an "anticommons" in which people underuse scarce resources because too many owners can block each other. Privatization of biomedical research must be more carefully deployed to sustain both upstream research and downstream product development. Otherwise, more intellectual property rights may lead paradoxically to fewer useful products for improving human health.

The tactual horizontal-vertical illusion depends on radial motion of the entire arm.

We sought to clarify the causes of the tactual horizontal-vertical illusion, where vertical lines are overestimated as compared with horizontals in L and inverted-T figures. Experiment 1 did not use L or inverted-T figures, but examined continuous or bisected horizontal and vertical lines. It was expected that bisected lines would be perceived as shorter than continuous lines, as in the inverted-T figure in the horizontal-vertical illusion. Experiment 1 showed that the illusion could not be explained solely by bisection, since illusory effects were similar for continuous and bisected vertical and horizontal lines. Experiments 2 and 3 showed that the illusory effects were dependent upon stimulus size and scanning strategy. Overestimation of the vertical was minimal or absent for the smallest patterns, where it was proposed that stimuli were explored by finger movement, with flexion at the wrist. Larger stimuli induce whole-arm motions, and illusory effects were found in conditions requiring radial arm motion. The illusion was weakened or eliminated in Experiment 4 when subjects were forced to examine stimuli with finger-and-hand motion alone, that is, their elbows were kept down on the table surface, and they were prevented from making radial arm motions. Whole-arm motion damaged performance and induced perceptual error. The experiments support the hypothesis that overestimation of the vertical in the tactual horizontal-vertical illusion derives from radial scanning by the entire arm.

Tactual picture identification by blind and sighted people: effects of providing categorical information.

Four experiments examined the influence of categorical information and visual experience on the identification of tangible pictures, produced with a raised-line drawing kit. In Experiment 1, prior categorical information aided to accuracy and speed of picture identification. In a second experiment, categorical information helped subjects when given after the examination of each picture, but before any attempt at identification. The benefits of categorical information were also obtained in another group of subjects, when the superordinate categories were named at the start of the experiment. In a third experiment, a multiple-choice picture recognition task was used to eliminate the difficulty of naming from the picture-identification task. The multiple-choice data showed higher accuracy and shorter latencies when compared with identification tasks. A fourth experiment evaluated picture identification in blindfolded sighted, early, and late blind participants. Congenitally blind subjects showed lower performance than did the other groups, despite the availability of prior categorical information. The data were consistent with theories that assume that visual imagery aids tactual perception in naming raised line drawings. It was proposed that part of the difficulty in identification of raised line pictures may derive from problems in locating picture categories or names, and not merely in perception of the patterns.

Production and interpretation of perspective drawings by blind and sighted people.

In three experiments the production and interpretation of perspective drawings by blind and sighted subjects were examined. Blindfolded sighted, early-blind, and late-blind subjects first attempted to produce raised-line drawings of a surface at a number of angles-0 degree (panel horizontal), -22.5 degrees, -45 degrees, -67.5 degrees, and -90 degrees (vertical). Congenitally blind subjects did not show foreshortening in their naive raised-line drawings. However, the congenitally blind subjects were able to understand aspects of perspective, and performed as well as the blindfolded sighted and late-blind subjects in a subsequent multiple-choice task. Subjects in the multiple-choice task were required to match tangible perspective drawings to a slanted board. Although the three groups performed alike, both groups of blind subjects performed better than blindfolded sighted controls on judgments involving drawings of the vertical panel in the second experiment. In a final experiment, in which vision and touch were compared, sighted subjects were required to adjust the angle of the panel to match foreshortened, perspective drawings. This experiment yielded significantly better performance with vision than with touch, but only for drawings of the board at the vertical orientation. The results suggested that congenitally blind people may benefit from haptic exposure to raised-line configurations representing geometric perspective.

Production and interpretation of pictures of houses by blind people.

Subjects were exposed to a three-dimensional model of a house and were asked to draw it using a raised-line drawing kit. Independent groups of ten each of sighted controls, early-blind, and late-blind subjects were told to identify the vantage point of tangible pictures of the model, including side views, 'bird's-eye' views from above, and views involving linear perspective. The ease or difficulty of picture interpretation depended upon the nature of the tangible drawing, with much better performance being recorded for side views. Performance was poor for foreshortened 3/4 views. Early-blind subjects were particularly unlikely to recognize views from above. In a control experiment with blindfolded sighted subjects the influence of prior information was examined: some subjects were told that the drawings could consist of side view or bird's-eye, top view, or 3/4 view drawings. This experiment showed that performance can be greatly improved through prior information about the nature of the tangible pictures.

Influence of visual guidance on braille recognition: low lighting also helps touch.

This study was an attempt to clarify the mechanisms responsible for the benefits of visual guidance in tactual braille recognition. Subjects touched +90 degrees tilted braille under normal room lighting, or with low lighting, with or without visual guidance. Both visual information about finger angle and spatial reference information were manipulated with stained glass and light-emitting diodes. The provision of visual information about finger angle alone was no help to braille recognition, and performance was low. Adding visual spatial reference information to vision of finger angle raised performance. However, recognition accuracy was also substantially improved by low lighting. The benefits of darkness for haptics did not generalize to the reading of upright, two-letter braille words. It was proposed that extraneous visual information may distract sighted subjects in haptic tasks that require mental rotation of visual images.

Mechanisms in the haptic horizontal-vertical illusion: evidence from sighted and blind subjects.

The haptic horizontal-vertical illusion was studied in two experiments. In Experiment 1, the illusion was relatively weak in sighted subjects and depended on stimulus size and the nature of the figure, that is, whether the pattern was an inverted-T or L shape. Experiment 2 compared early blind and late blind subjects. The illusion was present for an inverted-T figure but absent for an L figure in late blind subjects. However, the early blind subjects treated both the L and T figures as similar and showed the illusion to both. These results support the idea that visual experience may alter haptic judgments in sighted and late blind subjects.

The effect of orientation on tactual braille recognition: optimal touching positions.

Subjects in five experiments matched tangible braille against a visible matching code. In Experiment 1, braille recognition suffered when entire lines of braille characters were tilted in varying amounts from the upright. Experiment 2 showed that tilt lowered performance for tangible, large embossed letters, as well as for braille. However, recognition was better for print letters than it was for braille. In Experiment 3, subjects attempted to match the upright array against embossed braille that was left/right reversed, inverted up/down, or rotated +180 degrees. Performance was close to that for normal braille in the left/right reversal condition, and very low for the +180 degrees rotation group. These results on braille tilt in the "picture plane" may reflect difficulty in manipulating the tangible "image." Braille recognition performance was not lowered when the visible matching array was tilted -45 degrees or -90 degrees from the upright but the tangible stimuli were upright. In Experiment 4, recognition of left/right reversed braille that was physically horizontal (on the bottom of a shelf) was compared with that of braille left/right reversed due to its location on the back of a panel, in the vertical plane. Braille recognition accuracy was higher with braille located vertically. An additional experiment showed the beneficial effect of locating braille in the vertical, frontoparallel plane, obtained with +90 degree rotated braille. It is proposed that optimal tactual performance with tangible arrays might depend on touching position, and on the physical position of stimuli in space. Just as there are good and poor viewing positions, there may be optimal touching positions.(ABSTRACT TRUNCATED AT 250 WORDS)

Haptic dominance in form perception: vision versus proprioception.

An experiment placed vision and touch in conflict by the use of a mirror placed perpendicular to a letter display. The mirror induced a discrepancy in direction and form. Subjects touched the embossed tangible letters p, q, b, d, W, and M, while looking at them in a mirror, and were asked to identify the letters. The upright mirror produced a vertical inversion of the letters, and visual inversion of the direction of finger movement. Thus, subjects touched the letter p, but saw themselves touching the letter b in the mirror. There were large individual differences in reliance on the senses. The majority of the subjects depended on touch, and only one showed visual dominance. Others showed a compromise between the senses. The results were consistent with an attentional explanation of intersensory dominance.

Perspective taking, pictures, and the blind.

Congenitally blind, late blind, and blindfolded sighted controls attempted a Piagetian perspective-taking (three-mountain) task. Piaget used the term perspective to mean point of view (Piaget & Inhelder, 1967, p. 210), and the present usage does not imply linear perspective. Subjects used raised-line drawings to depict alternative points of view of an array of three geometric solid forms (cube, cone, and ball). They then identified the point of view of raised-line drawings. The effect of visual status on accuracy was nonsignificant for both response measures. Using alternating vision of the array and drawings, sighted subjects in a control condition performed like the congenitally blind. However, congenitally blind individuals did require more time than the other subjects for the perspective-taking task. In an additional experiment, no difference was found between the three groups in the accuracy or speed of tactile shape matching. The results suggest that visual imagery and visual experience are not necessary for tactile perspective taking.

Tactile pattern recognition with the Optacon: superior performance with active touch and the left hand.

Independent groups of subjects (n = 12) attempted to identify individual digits 0-9 using active or passive touch with a vibrotactile display (Optacon II). Repeated measures were taken on the hand factor. Number recognition was superior with active touch and with the left hand.

Texture perception in sighted and blind observers.

The purpose of the present study was to evaluate the utility of visual imagery for texture perception. In Experiment 1, sighted, early-blind, and late-blind observers made relative smoothness judgments of abrasive surfaces using active or passive tough. In Experiment 2, subjects compared vision and touch in the accuracy of smoothness detection, using a broad range of textures, including very fine surfaces. No differences appeared between the sighted and the blind, and it did not matter if touch were active or passive. Vision and touch showed similar performance with relatively coarse textures, but touch was superior to vision for much finer surface textures. The results were consistent with the notion that visual coding of tactual stimuli is not advantageous (or necessary) for texture perception, since touch may hold advantages for the detection of the smoothness of surfaces.