Daniel Kish’s life reads like the origins story out of a super hero comic book. To treat his cancer, doctors removed both Kish’s eyes when he was aged one. Later, as a child, he taught himself to echolocate like a bat. Using the echoes from his own clicking sounds he detects the world around him. He can even cycle busy streets and it’s his life’s mission to empower other blind children by teaching them echolocation or what he calls flashsonar.
Psychologists studying the skill have found that it is eminently teachable, for blind people and the sighted. But what’s also become clear is that there is a huge amount of variation between individuals: some people, blind or sighted, seem to pick it up easily while others struggle. A new study in Experimental Brain Research is among the first to try to find out which mental abilities, if any, correlate with echolocation aptitude. The findings could help screening to see who is likely to benefit from echolocation and offer clues to how to help those who struggle.
Marina Ekkel and her colleagues blindfolded 23 sighted undergrad participants and asked them to sit opposite a small acrylic disc and a large disc. One disc was always located higher than the other with the positions switched discreetly from trial to trial. Each trial, the participants’ task was to identify the respective location of the discs.
The participants wore a small speaker on their foreheads and on each echolocation trial, to help them locate the discs, they could press a button to emit a short burst of white noise from this speaker as many times as they wanted for up to 20 seconds (on average, the participants chose to make 2.7 sounds). On control trials they had to locate the discs without making any sounds.
Although participants were allowed to move their heads (doing so makes echolocation much more effective), five participants chose to always kept their heads still and they never performed any better than if they’d just guessed at random, so their data was omitted from further study.
As well as performing four sessions of the echolocation tests for one to two hours over two days, the remaining participants also completed tests of their cognitive abilities including: their spatial cognition (based on their ability to remember the location of shapes on a plate); their working memory (recalling lists of digits); and their sustained and divided attention (they took the “Paced Auditory Serial Addition Task/PASAT”: presented with a series of 60 single-digit numbers, they had to add each new number to the preceding one and state the sum out loud).
Overall, the participants never performed better than chance in the control trials – they may as well have been guessing. In contrast, average correct performance across the echolocation trials was 63.2 per cent. There was also a clear training effect with performance in the fourth session clearly outstripping performance in the first. But consistent with past research, there were again large differences in individual aptitude: in the final sessions, the top performing participant managed 96 per cent accuracy versus 48 per cent achieved by the lowest performer.
Comparing participants’ echolocation improvement with their performance on the other cognitive tests, only their sustained and divided attentional abilities were relevant. The higher participants scored on the PASAT attentional test, the more improvement they showed in echolocation. This makes sense if you consider the concentration that must be involved in using echolocation effectively. By contrast, participants’ scores on spatial cognition and working memory did not correlate with their echolocation skills.
These results add to past research that’s shown people who lose their sight earlier in life tend to find it easier to learn echolocation, perhaps because they’ve had more practice using other senses to compensate for their lack of sight. The new findings suggest that attentional abilities are another key factor that’s relevant. Screening based on attentional skills might help identify those most likely to benefit from echolocation training, or perhaps honing attention skills could be a useful adjunct to training in echolocation. For now all this is highly speculative: the present results were correlational (it’s not necessarily the case that attentional skills are directly relevant), and among things, we need to see if the results replicate in blind participants.
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