Two-point Touch Research Articles

Assessment of the effects of white cane variables on step symmetry of blind individuals.

Step symmetry is an important feature of human gait and is often regarded as a key index of healthy individuals' walking. This study evaluated the effects of height, white cane technique, and cane tip on symmetrical gait in blind individuals. Twenty blind and ten sighted subjects, aged 15-38 years, participated in this study. The harmonic ratio (HR) and improved HR (iHR) were measured by trunk accelerometer as gait symmetry index in three axes: anteroposterior (AP), vertical, and mediolateral of the body. These parameters were measured in the sighted group in open-eye conditions and in the blind group in five experimental conditions with different two heights (standard and long), two tips (pencil and roller), and two techniques (two-point touch and constant contact) of white cane when they walked in the 6-m path. There was a significant difference between HR and iHR of the blind and sighted group, which indicates a significant reduction of symmetry loss in the blind group. Among the five different conditions studied in the group of blind people, an increase was observed in the HR and the iHR on the AP axis during the application of a standard cane with a roller tip, which indicated an increase in symmetry. Based on the results, a long cane with a pencil tip and a standard cane with a roller tip in the constant contact technique can increase step symmetry.

Orientation and Mobility Assessments for Children and Youths With Visual Impairments: How, Why, When, and Where?

Introduction: This study analyzed survey responses from 114 orientation and mobility (O&M) specialists regarding the content and procedures they used in completing O&M assessments. Methods: O&M specialists completed an online survey in 2020 on their assessment practices for children and youths who are visually impaired. Results: Over 85% of participants identified that they interview the student, parent, classroom teacher, and teacher of students with visual impairments as part of the assessment. The only visual skills addressed by at least 80% of participants were depth perception, distance acuity, scanning, and peripheral visual fields. Students without additional disabilities in kindergarten through 12th grade were more likely to be taught the two-point touch cane technique when compared to students with additional disabilities, who were more likely to be taught constant contact. Discussion: Participants identified that O&M assessments for students in 9th–12th grade were more likely to focus on skills that would be needed for employment or post-secondary education or both, such as the use of public transportation. For students with additional disabilities or children under the age of five years, participants were more likely to conduct assessments focused on safety and immediate needs and environments. Implications for Practitioners: Appropriate O&M assessments need to be conducted in natural environments that provide equal challenges to the environments where students need to travel. O&M specialists must adapt the assessment content and procedures to address the current and future travel needs of all students with visual impairments.

Drop-off detection with the long cane: effect of cane shaft weight and rigidity on performance

Most travellers who are blind rely on a long cane to detect drop-offs on their walking paths. We examined how different cane shaft materials affect drop-off detection performance through providing different vibrotactile and proprioceptive feedbacks to the cane user. Results of the study showed a significant interaction between cane shaft weight and how the cane is used. A heavier cane was advantageous for detecting drop-offs when the individual used the ‘constant contact technique’ – cane tip stays in contact with the walking surface at all times – but not when he used the ‘two-point touch technique’ – cane tip is rhythmically tapped on the surface. In addition, a more flexible cane was advantageous for detecting drop-offs when the two-point touch technique was used but not when the constant contact technique was used. It is recommended that, when blind individuals select a cane shaft material, they consider which long cane technique they use more often.Practitioner Summary: Long cane shaft material affects how well a blind individual can detect drop-offs. A heavier shaft was advantageous when using the constant contact technique (cane tip stays in continuous contact with the surface), while a more flexible shaft was better when using the two-point touch technique (cane tip rhythmically taps the surface).

Force sensing model of capacitive hybrid touch sensor using thin-film force sensor and its evaluation

This paper suggests the concept model of hybrid touch sensor that can detect touch locations and each force component in case of single or two-point touch event. The model is to calculate each force component using known touch locations obtained from commercial projective capacitive touch module. The suggested model consists of four thin-film force sensors and a tempered glass plate instead of commercial capacitive touch sensor. The force sensors are fabricated easily by simple screen printing technique and evaluated by calibration setup. Eleven single-touch events are performed to obtain the maximum deviation error of force responses with respect to touch locations. Additionally, we perform two-point touch events using a transitional load and a dead weight load (50 g or 100 g) to verify the proposed hybrid touch model. The obtained force components are compared with two input loads. It is confirmed that the hybrid touch sensor can provide satisfactorily the location of contact and the force response. Finally, we expect that the proposed touch model can detect the touch locations and force components simultaneously in case of single or two touch events.

Effect of Cane Technique on Obstacle Detection with the Long Cane

Modern long cane (also known as the white cane) techniques have changed little since their development in the 1940s. The two-point touch and the constant-contact techniques are the two used most widely by travelers who are blind. Regardless of which technique is used, obstacle detection, a key component of preview offered by a long cane (Blasch, La Grow, & De l'Aune, 1996), is crucial for the safety of blind travelers. When obstacles such as construction cones or toys left on the sidewalk are missed, they may trip the cane user, resulting in falls and consequent fall-induced injuries. Several recent studies have examined how different factors affect drop-off detection with the long cane. Cane users detected drop-offs more reliably when they used the constant-contact technique than when they used the two-point touch technique, particularly if they were inexperienced cane users respectively (Kim, Wall Emerson, & Curtis, 2009; Kim, Wall Emerson, & Curtis, 2010a). Younger cane users and those with earlier-onset visual impairments detected drop-offs better than older cane users and those with later-onset visual impairments (Kim, Wall Emerson, & Curtis, 2010b). However, drop-off detection performance with a standard marshmallow tip was similar to that with a marshmallow roller tip (Kim, Wall Emerson, & Curtis, 2010c). In addition, a cane length difference of 10 inches did not result in a significant difference in drop-off detection (Kim & Wall Emerson, 2012). In respect to obstacle detection, La Grow, Blasch, and De l'Aune (1997a) reported that participants achieved the greatest detection distance for foot-level objects (those that are not higher than the ankle) when the hand holding the cane was held at the midline and positioned below the waist. In another study, La Grow, Blasch, and De l'Aune (1997b) also documented that the two-point touch technique did not provide consistent surface previewing for four of seven participants. Wall and Ashmead (2002) found that pivoting the wrist when swinging the cane resulted in better body coverage than did moving the whole arm. The reliability of traditional cane techniques for detecting obstacles is of particular interest because some of the previous studies reported path coverage rates that were inadequately low (61-69%) when the participants used the two-point touch technique (Uslan, 1978; Wall & Ashmead, 2002). Although one orientation and mobility (OM La Grow & Long, 2011). What is of additional interest is whether the constant-contact technique indeed has an advantage over the two-point touch technique in detecting low obstacles. Such claims have been made by many cane users based on the fact that the cane tip stays in contact with the walking surface at all times when the constant-contact technique is used. However, these claims have been solely based on anecdotes and have not been examined empirically. The purpose of the present study was to examine how reliable the traditional cane techniques are for detecting obstacles and whether the type of cane technique affects obstacle detection as it interacts with the height of the obstacles. [FIGURE 1 OMITTED] METHOD Study design and recruitment criteria A repeated-measures design with block randomization was used for the study. We recruited 14 sighted students (7 female and 7 male) aged 22 to 62 (median age = 26) from Western Michigan University's (WMU) O&M program. The participants were familiar with both the two-point touch and the constant-contact techniques and their cane use experience ranged from one month to four months (median experience = four months). …

基于光学的真三维触控定位与识别方法研究

A two-point touch method for three-dimension space is proposed through introducing true three-dimension display and unmarked spatial orientation,while a two-point touch for true three-dimension display system is built.Interactive approach,which offers the solution of spatial orientation,tracking and gesture recognition,has been considered.Demonstrated in the experiments,optical-based two-point touch system meets the needs of human-computer interaction without any markers and sensors and changes of ambient light does not interfere with the operation of the human-computer interaction.

A Seamless Approach to Transitioning Cane Skills from the Diagonal to the Two-Point Touch Technique

The profession of orientation and mobility (OM Jacobson, 1993; LaGrow & Long, 2011; LaGrow & Weesies, 1994), strategies for teaching OM Fazzi & Naimy, 2010; Griffin-Shirley & Welsh, 2010; Skellinger & Sapp, 2010; Welsh, 2010), rationales, and appropriate settings (Hill & Ponder, 1976; Jacobson, 1993; LaGrow & Weesies, 1994; LaGrow & Long, 2011). These strategies and techniques are also addressed in many university preparation programs. All the foregoing authorities have done an excellent job of using task analysis to describe specific cane techniques, and some have even offered suggested sequences for introducing skills and presented teaching strategies. However, there is an apparent paucity of information on specific activities that are necessary to connect the dots for practitioners that make sense to students and that provide a nearly seamless transition from what has been learned previously to what needs to be learned. Such information may be provided by practitioners who have determined from their experience what works best with students who are blind. A case in point is the two-point touch technique (Hill & Ponder, 1976; Jacobson, 1993; Knott, 2002; LaGrow & Long, 2011; LaGrow & Weesies, 1994). All agree that there are essentially seven components to this primary mobility skill for travel in familiar and unfamiliar environments. These components are: the position of the cane (at the midline), the index finger down the flat side of the grip, wrist action (flexion, extension, and hyperextension), the height of the (no more than 1.5 inches off the surface at the apex of the arc), the width of the (approximately 1 inch beyond the widest parts of the student's body), rhythm (the cane taps the surface each time either of the student's heels touches the surface), and staying in step (the cane taps on the opposite side of the foot touching the surface). Note that Pogrund et al. (2000) identified nine components for the same skill by separating the arm position and the hand position and adding an additional component in-step correction (that is, skipping or tapping the cane twice on the same side to get back in while Knott (2002) identified only six steps. However, differences between these techniques are descriptive rather than substantive. I have frequently observed that if the skill set known as the two-point touch technique is taught as a whole, both the student and the instructor are often frustrated. Such attempts are characterized by constant verbal corrections--for example, arc left, right, get in right, cane at the midline, not enough coverage on your right, your is too high, you're out of step, ad nauseam! As a solution, when using this strategy, the instructor is advised to introduce the components one step at a time, starting with the diagonal technique. It should be emphasized that the following is just one strategy, not the only strategy, for teaching the two-point touch technique, and, as a professional, the instructor has every right to make modifications that he or she deems appropriate for the individual student who is blind. The diagonal technique is usually the first independent cane technique that is taught to students. Succinctly, it serves the purpose of being a bumper that is far more effective than the lower hand and forearm protective technique, and can be used to trail vertical surfaces for alignment and to locate doors and intersecting hallways. In addition, this technique is extremely easy to teach, easy to learn, and infinitely functional for familiar indoor environments where there is no danger of drop-offs or stairs, and may used to make the transition easily and seamlessly to the two-point touch technique. …

Effect of Cane Length on Drop-off Detection Performance

Although individuals who are blind have used a stick or a cane for their independent travel since the early years of human history, designs for modern long canes did not appear until World War II, when the systematic long cane techniques were developed by Hoover (1962). Ergonomic factors, such as the length of the cane, may affect how well a cane user can detect the presence of obstacles and changes in surface elevation, including drop-offs. Reliable drop-off detection with a long cane, an essential component of surface preview (Blasch, La Grow, & De l'Aune, 1996), is critical for the safety of travelers who are blind who use canes, since missing drop-offs or other changes in elevation in the walking surface may cause them to fall or accidentally stumble into the collision path of approaching vehicles. Kim, Wall Emerson, and Curtis (2009) found that cane users were able to detect drop-offs more reliably when they used the constant contact technique than when they used the two-point touch technique. The characteristics of cane users may also influence the users' performance in detecting drop-offs. In Kim, Wall Emerson, and Curtis's (2010a) study, younger users were able to detect drop-offs more reliably than were older cane users. Cane users who lost their vision early in life also detected drop-offs more reliably than did those who lost their vision later (Kim et al., 2010a). In addition, those who had regularly used a cane for at least two years performed better than did those who were less experienced (Kim, Wall Emerson, & Curtis, 2010c). Detecting drop-offs may also be influenced by ergonomic factors, such as the type of cane tip (Kim, Wall Emerson, & Curtis, 2010b) and length of the cane (Rodgers & Wall Emerson, 2005). How the length of a cane may affect the detection of drop-offs is of particular interest because there appear to be different opinions on this matter among cane users. According to the traditional method (called the method), a proper cane length is defined as the vertical distance from the ground to 2 inches above the xiphoid process (La Grow & Weessies, 1994). In a study conducted with 10 adult cane users who were visually impaired (that is, those who were blind or had low vision), Rodgers and Wall Emerson (2005) reported that the use of a standard-length cane, measured by the sternum method, allowed the users to detect drop-offs significantly better than with the canes that were either 5%-15% shorter or 10%-20% longer than the standard length. However, some cane travelers have advocated for a cane that is substantially longer than the standard length. For example, Willoughby and Monthei (1998) suggested that although a cane user' s stride, walking speed, and reflexes should be considered, a cane that reaches only to the sternum is not long enough to ensure safety for an average cane user. In addition, Kish (2009) suggested, on the basis of personal anecdotal experience, that children up to age 6 should use canes that are as long as their height and that adult travelers need to use canes that are about chin high. Given this controversy, we investigated whether the length of the cane affects the detection of drop-offs. We also examined whether there is an interaction between the length of a cane and the depth of a drop-off. METHOD A repeated-measures design with block randomization was used for the study. We recruited 15 sighted students (13 female and 2 male) aged 22 to 55 (median age = 34) from the orientation and mobility (O&M) program at Western Michigan University who were familiar with both the two-point touch and constant contact techniques. These students had received 1 month to 4 months (median = 1.4 months) of cane training. A 32-foot-long walkway with six carpeted plywood platforms (8 feet long, 4 feet wide, and 8 inches high) was used for the study. We placed two plywood boards (2 feet long and 4 feet wide) on top of braced rectangular frames (2 feet long, 4 feet wide, and 2 inches high) against the lengthwise end of the walkway to change the depth of the drop-off from trial to trial. …

Two-point touch discrimination depends on the perceived length of the arm

Two-point discrimination threshold depends on the number and size of receptive fields between the touches. But what determines the size of the receptive fields? Are they anatomically fixed? Or are they related to perceived body size? To answer this question we manipulated perceived arm length using the Pinocchio illusion. The test arm was held at the wrist and the holding arm was made to feel perceptually more extended than it was by applying vibration to the tendon of the biceps (cf. de Vignemont et al., 2005). For control trials the holding arm was vibrated elsewhere. An array of tactors, separated by 3 cm, was placed on the upper surface of the arm and covered with a cloth. Vibro-tactile stimulation was applied to either one or two tactors in two periods. Subjects identified which period contained two stimuli. A psychometric function was drawn through the probability of correct response as a function of tactor separation to determine the threshold distance. In a separate experiment, subjects estimated the perceived location of each tactor against a scale laid on top of the cloth. The estimated locations of the tactors on the tested arm were displaced by tendon vibration of the holding arm compatible with a perceptual lengthening of the arm. The threshold for two-touch discrimination was significantly increased from 4.5 (±0.6) cm with no tendon stimulation to 5.7 (±0.5) cm when the arm was perceptually extended. We conclude that two-point touch discrimination depends on the size of central receptive fields that become larger when the arm is perceptually lengthened.

Interaction Effects of the Amount of Practice, Preferred Cane Technique, and Type of Cane Technique Used on Drop-off Detection Performance

This study examined the interaction effects of the amount of practice and the cane technique used in drop-off detection with a sample of 32 adults who were blind. The advantage of the constant contact technique over the two-point touch technique was significantly greater for the less experienced cane users than for the more experienced ones.

Ergonomic Factors Related to Drop-Off Detection With the Long Cane: Effects of Cane Tips and Techniques

This study examined the effect of cane tips and cane techniques on drop-off detection with the long cane. Blind pedestrians depend on a long cane to detect drop-offs. Missing a drop-off may result in falls or collision with moving vehicles in the street. Although cane tips appear to affect a cane user's ability to detect drop-offs, few experimental studies have examined such effect. A repeated-measures design with block randomization was used for the study. Participants were 17 adults who were legally blind and had no other disabilities. Participants attempted to detect the drop-offs of varied depths using different cane tips and cane techniques. Drop-off detection rates were similar between the marshmallow tip (77.0%) and the marshmallow roller tip (79.4%) when both tips were used with the constant contact technique, p = .294. However, participants detected drop-offs at a significantly higher percentage when they used the constant contact technique with the marshmallow roller tip (79.4%) than when they used the two-point touch technique with the marshmallow tip (63.2%), p < .001. The constant contact technique used with a marshmallow roller tip (perceived as a less advantageous tip) was more effective than the two-point touch technique used with a marshmallow tip (perceived as a more advantageous tip) in detecting drop-offs. The findings of the study may help cane users and orientation and mobility specialists select appropriate cane techniques and cane tips in accordance with the cane user's characteristics and the nature of the travel environment.

Drop-off Detection with the Long Cane: Effects of Different Cane Techniques on Performance

This study compared the drop-off detection performance with the two-point touch and constant contact cane techniques using a repeated-measures design with a convenience sample of 15 cane users with visual impairments. The constant contact technique was superior to the two-point touch technique in the drop-off detection rate and the 50% detection threshold. The findings may help an orientation and mobility instructor select an appropriate technique for a particular client or training situation.

Changes in Biomechanical Features of the Two-point Touch Technique as it is Learned

This study sought to chart biomechanical changes in the performance of the two-point touch technique as it was learned by four sighted, blindfolded adults with no previous cane experience. The results indicate that these participants acquired the basic biomechanical movements of the two-point touch technique rapidly, and their performance approached that of the levels of experts after minimal training.

Biomechanical Movements in Experienced Cane users with and without Visual Impairments

Travelers with visual impairments and orientation and mobility (O&amp;M) instructors were assessed in their performance of the two-point touch cane technique. Both groups deviated similarly from classical stipulations of the technique, having wider arc widths and hand positions off of midline. Measures of body coverage and rhythm were less than ideal. Foot placement preview was linked to several factors. The possibility of focusing more on coverage than on rhythm when assessing cane use is postulated.

Biomechanical Substrates of the Two-point Touch Cane Technique: A Review of Research

This article reviews research on the biomechanical elements related to the most commonly used long cane technique: two-point touch. The use of several natural biomechanical tendencies supports the contention that the technique is inherently efficient.

Taste sensitivity and aging: high incidence of decline revealed by repeated threshold measures.

Contrary to what has often been said about the subject, decline in taste sensitivity with aging characterizes virtually everybody and is not the artificial result of averaging large losses of a minority with negligible losses of a majority. This assertion is supported by six repeated measures of sucrose thresholds in each of 15 older (over 64 years) and 15 younger (under 27 years) adult subjects. Threshold was determined by a procedure similar to past studies and with the same results: much scatter and considerable overlap between the thresholds of younger and older subjects. A quite contrasting picture emerges, however, when each subject's six threshold determinations are averaged. Averaging shrinks the individual differences among subjects, as well as the over-lap between younger and older subjects. Although virtually all elderly subjects now revealed taste weakness, reliable individual differences in degree of weakness abound among them, suggesting various individual rates of physiological aging. In contrast, young persons exhibit greater uniformity of sensitivity. These findings were brought out by inter-test correlations, which were much higher for the older subjects; i.e. an older subject who tended to score high (low) on one test tended to score high (low) on the other tests. The study confirms the tenuous nature of brief threshold tests as indices of personal sensitivity as found earlier also in olfactory thresholds and in concurrent measurement of two-point touch thresholds in the present study. This revealed correlated losses between repeated taste and touch thresholds from the same 15 older subjects, unrelated to their exact chronological age.

The Application of Two-Point Touch Cane Technique to Theories of Motor Control and Learning Implications for Orientation and Mobility Training

Basic behavioral processes involved in motor control based on theories of motor control and learning are outlined using the teaching of two-point touch cane technique as an application of the theories. The authors believe that the keys to successful mobility training are repetition and correctly performed practice of each skill and sufficient learning time to facilitate overlearning and subsequent skill retention.

The Two-Point Touch Technique Comes Naturally

The Two-Point Touch Technique Comes Naturally

Modification of the Two-Point Touch Cane Technique: A Pilot Study

In this pilot study four subjects were observed to determine the extent of the natural movement of their centers of gravity in relation to arc height during the two-point touch cane technique. The subjects learned and practiced a modified technique using their center of gravity as much as possible. Analysis of the data revealed that each subject was, to some extent, able to incorporate the movement of the center of gravity into the two-point touch technique.

Objective determinations of sensibility in the upper extremity. Part III. Application of cutaneous stimuli in patients with peripheral nerve lesions.

Quantitative values for pressure, electrical, and two-point touch stimulation were examined in five patients with peripheral nerve injuries of the ulnar or median nerves. Analyses of profiles generated for each stimulus application in each patient participating in this preliminary study suggest that, following the reading of a sensitization statement, pressure and electrical shock threshold values are clearly reduced compared to similar measurements in the unaffected limb. Values obtained prior to the statement indicated progressively reduced thresholds, however. Changes in sensation appear to precede significant improvements in sensory nerve conduction velocity. Limitations in the sensory testing techniques as well as suggestions for improving its validity are discussed.