Alan McStravick for redOrbit.com — Your Universe Online
Fascination with the study of split brain, or laterality, is not a new occurrence within the scientific community. Some of the better-known studies, conducted in the 1960s, dealt with individuals whose corpora callosa was surgically severed due to their affliction with epilepsy. While today brain imaging devices are more likely to be used to observe this phenomenon, psychologists continue to engage in research in the field of brain laterality.
One of the simplest procedures available to monitor laterality in normal populations is through the use of dichotic listening experiments. Dichotic listening experiments are performed by presenting two stimuli, one to each ear. The research centers around the individual´s ability to accurately identify the sounds presented. Auditory laterality studies offer insight into two areas of psychology: perception and cognition. The use of auditory laterality studies are still used by researchers to study how information is processed with respect to hemisphere specific tasks.
The first use of the dichotic listening procedure to study laterality was introduced by Donald Broadbent in 1954. Doreen Kimura later refined the procedure by presenting different digits to each ear through stereo headsets. Their findings showed most people were able to correctly recall the digits presented to the right ear. It was in the 1970s other researchers adapted the procedure, presenting meaningless syllables rather than actual words or digits.
The dichotic listening procedure seems poised for its latest renaissance, thanks to researcher Josef Bless. It was two years ago, while listening to music on his phone, he was suddenly struck with inspiration.
“I noticed that the sounds of the different instruments were distributed differently between the ears, and it struck me that this was very similar to the tests we routinely use in our laboratory to measure brain function. In dichotic listening, each ear is presented with a different syllable at the same time (one to the left and one to the right ear) and the listener has to say which syllable seems clearest. The test indicates which side of the brain is most active during language processing,” Bless explains.
Bless, currently working on a PhD in psychology at the University of Bergen, is a member of the Bergen fMRI Group. The Bergen fMRI Group is an interdisciplinary research group headed by Professor Kenneth Hugdahl. Hugdahl is a previous recipient of the European Research Council (ERC) Advanced Grant for his work in the field of brain research.
Where technology and psychology intersect is in Bless´ development of an iPhone app designed to administer the dichotic listening procedure. Their app, called iDichotic, was launched in 2011 as a free download from the Apple´s App Store. In just a year´s time, more than 1000 people had downloaded the app, with roughly half of those individuals having sent in their test results to the researchers´ database.
The iDichotic app is very simple to use. The listening test takes just three minutes to complete. Results will let the user know which side of their brain is most active in language processing. While most people primarily use the left side of their brain for language processing, a minority (including many left-handed people) use the right side of their brain for this task. Additionally, iDichotic measures attention when the task is to focus on one ear at a time.
An analysis of the first 167 test results received was compared with test results of 76 individuals who had been tested in a laboratory setting in Norway and Australia. Results of this comparative analysis have been published in the journal Frontiers in Psychology.
“We found that the results from the app were as reliable as those of the controlled laboratory tests. This means that smartphones can be used as a tool for psychological testing, opening up a wealth of exciting new possibilities,” says Bless.
“The app makes it possible to gather large volumes of data easily and inexpensively. I think we will see more and more psychological tests coming to smartphones,” he adds.
The University of Bergen team has gone on to develop a special version of their iDichotic app that is geared specifically for patients with schizophrenia who suffer from auditory hallucinations. The app, they claim, assists in the training of these patients, helping them to improve their focus. This heightened focus will allow the patient, when they hear voices, to be better able to shut these hallucinations out.
“Using a mobile app, patients can be tested and receive training at home, instead of having to come to our laboratory,” says Bless.
The use of iDichotic could have future, far-reaching applications. Conditions such as Alzheimer´s disease, sleep deprivation and dyslexia could be better studied and even improved as a result of dichotic listening procedures. In fact, in 2005, through the use of this procedure, researchers were able to determine people with mild Alzheimer´s disease showed a much greater right ear advantage than those suffering from an even milder form of the disease. This finding demonstrates that the disease influences attentional processes. It is also known sleep deprivation impacts attentional control. And in 2001, it was reported that dyslexic children displayed less laterality of language than did normal control subjects. In short, the use of dichotic listening procedures remain an important diagnostic tool in the field of brain research and psychology.
The iDichotic app has been developed in collaboration with Professor Kenneth Hugdahl, Doctor RenÃ© Westerhausen, and Magne Gudmundsen.
Alan McStravick for redOrbit.com — Your Universe Online