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). …