Human click-based echolocation: Effects of blindness and age, and real-life implications in a 10-week training program

Abstract

Understanding the factors that determine if a person can successfully learn a novel sensory skill is essential for understanding how the brain adapts to change, and for providing rehabilitative support for people with sensory loss. We report a training study investigating the effects of blindness and age on the learning of a complex auditory skill: click-based echolocation. Blind and sighted participants of various ages (21–79 yrs; median blind: 45 yrs; median sighted: 26 yrs) trained in 20 sessions over the course of 10 weeks in various practical and virtual navigation tasks. Blind participants also took part in a 3-month follow up survey assessing the effects of the training on their daily life. We found that both sighted and blind people improved considerably on all measures, and in some cases performed comparatively to expert echolocators at the end of training. Somewhat surprisingly, sighted people performed better than those who were blind in some cases, although our analyses suggest that this might be better explained by the younger age (or superior binaural hearing) of the sighted group. Importantly, however, neither age nor blindness was a limiting factor in participants’ rate of learning (i.e. their difference in performance from the first to the final session) or in their ability to apply their echolocation skills to novel, untrained tasks. Furthermore, in the follow up survey, all participants who were blind reported improved mobility, and 83% reported better independence and wellbeing. Overall, our results suggest that the ability to learn click-based echolocation is not strongly limited by age or level of vision. This has positive implications for the rehabilitation of people with vision loss or in the early stages of progressive vision loss.

No effect of 10-week training in click-based echolocation on auditory localization in people who are blind

“…Thus, although previous research has shown that blind echolocation experts performed better than blind participants on both of these tasks of auditory localization (Tonelli et al 2020 ; Vercillo et al 2015 ), we did not find evidence supporting the idea that performance improved with echolocation training in blind people. It is important to note that this null effect is not due to a limited ability of participants to learn click-based echolocation—in fact, participants’ performance in click-based echolocation improved in three different echolocation tasks (size discrimination, orientation identification, virtual navigation) to a level that in most (but not all) cases matched performance demonstrated by experts (Norman et al 2021 ; and Supplementary Material S1). Thus, significant improvement in click-based echolocation ability over the course of 10 weeks was not sufficient to confer improvements in auditory localization ability.…”

“…Thus, a 10-week period might not be long enough for the effects to take place. Related to this, even though training led to a dramatic improvement in echolocation ability in all participants, highest performance was achieved only at the end, and performance did not match the performance of experts in all tasks [e.g., in the size discrimination task, participants did not perform as well as experts even after 10 weeks of training, see Norman et al ( 2021 )]. Thus, it is possible that more training or longer periods of use of this skill might be needed to achieve effects.…”

“…Details of the training and training results are described in Norman et al ( 2021 ), but all raw data for training results are also contained in Supplementary Material S1. Briefly, all participants were trained to echolocate using mouth clicks over the course of 10 weeks (20 sessions, each between 2 and 3 h in length).…”

“…Thus, we had sufficient power in our study. Details of the sample have been described in Norman et al ( 2021 ) but are also listed in Table 1 and described here. In our sample, all BCs had a cause of vision loss present from birth.…”

“…(Ekkel et al 2017 ; Teng and Whitney 2011 ; Thaler et al 2014 ) or active echolocation using footsteps or cane-taps (Kolarik et al 2017 ; Thaler et al 2019 ). It has also been shown that click-based echolocation provides real-life advantages for people who are blind in terms of their mobility, independence, and wellbeing (Norman et al 2021 ; Thaler 2013 ).…”