Auditory verbal hallucinations refer to the phenomenological experience of hearing voices in the absence of external acoustic stimuli. This experience is often characterized by a negative emotional valence, difficulty in inhibiting or ignoring the voices, and an inward direction of attention at the expense of external attentional awareness. More often than not, these hallucinations are condemnatory in nature, in the form of insults, comments, and commands aimed at the person experiencing them. The latter are especially dangerous, as the voices may command the patient to engage in violent, unlawful actions. Additionally, the patient may have to deal with the anxiety of having to comply with such commands. In rare cases, the voices may be of benevolent, encouraging nature.
Auditory verbal hallucinations are a defining symptom of psychosis and schizophrenia. This seemingly inescapable internal dialogue drains the cognitive resources of the patient, resulting in reality disorientation, emotional distress, and impairment in daily functioning. Neuroimaging studies have implicated the temporal lobe and related regions in the occurrence of auditory hallucinations. Spontaneous neural activation in the brain regions responsible for normal speech production has been found to be responsible for auditory hallucinations. Moreover, this abnormal brain activity interferes with the processing of external sounds. Neuroimaging studies also report that patients with schizophrenia who experience auditory hallucinations have reduced grey matter volume in temporal and frontal lobes as well as an altered connectivity between frontal, temporal (language integration), and anterior cingulate (attentional) networks. Together, these findings have important clinical implications.
Kenneth Hugdahl, a professor of Biological Psychology at the University of Bergen, Norway has proposed the VOICE model based on the aforementioned neural correlates of auditory hallucinations. According to this model, auditory hallucinations occur as a result of the failure of two systems: bottom-up and top-down systems. The bottom-up system consists of sensory and perceptual processes that respond to stimuli features while the top-down system consists of processes that respond to situation demands. Auditory hallucinations are initiated by the failure of the bottom-up system, resulting in spontaneous temporal hyperactivation in the absence of external auditory stimuli. Further, they are maintained by the failure of the top-down system manifested in the disinhibition of these internally generated voices by a hypoactive frontal lobe as well as an inward focus of attention by the parietal lobe. The VOICE model speculates that auditory hallucinations may be treated with the help of cognitive training to reinstate the top-down system and reallocate attention away from the internally generated voices.
Professor Hugdahl makes use of a dichotic listening paradigm in the context of auditory hallucinations, both as a tool for research and clinical training. This involves the simultaneous presentation of two different consonant-vowel pairings (eg. ba-da) in each ear. Further, participants are either asked to freely report the sounds they hear or are explicitly instructed to attend to a particular ear. In the free report condition, participants tend to report the stimuli coming from the right ear rather than the left ear. This tendency, known as the right ear advantage, is an important aspect of normal speech processing. Speech perception in healthy individuals is localized to the temporal lobe of the left hemisphere. Since auditory nerves are bilateral, input from the right ear is directly accessed by the speech processing centres localized in the left temporal lobe, thereby giving it an advantage in processing.
Through their studies, Professor Hugdahl and his colleagues found that the magnitude of auditory hallucinations was negatively correlated with the right ear advantage in patients with schizophrenia. Josef Johann Bless, a colleague of Professor Hugdahl, developed a smartphone app based on the dichotic listening paradigm; this is now used as a clinical training tool. Developed under the supervision of Professor Hugdahl, the app called iDichotic, presents its user with 30 pairs of consonant + vowel sounds. An arrow on the screen instructs the user about which ear to attend to. In order to report the syllable that was heard, the user must click the correct syllable on the screen from the given options. At the end of each trial, the user is provided with performance feedback. With practice, users can learn to shift their attention to the ear that they are instructed to attend to, simultaneously blocking out the sound coming from the other ear. The aim of the app is to train patients with schizophrenia to voluntarily direct attention to external auditory stimuli and cognitively inhibit the interfering inner voices, through transfer learning. While it is yet to be tested on an adequate sample to obtain reliable results, the feedback from initial testing has been promising. Although the voices do not completely disappear, following the training period, patients report feeling more in control of them.
The feasibility of the use of such self-supervised devices was established through a study which confirmed that the results obtained through the use of this app were comparable to those obtained in laboratory experiments. A similar application was developed by Bless and colleagues for the purpose of for real-time data collection on auditory hallucinations.The app, iVoice, asks the users to self-report their symptoms across the dimensions of control, content, localisation, intensity and influence, 5 times a day. While the primary aim of the app was to record temporal fluctuations in the symptoms, it has been found that simply keeping a track of these symptoms improved the perceived control and content of auditory hallucinations in patients.
The primary advantage of such cunning use of technology lies in the ease with which it can be used in public settings — by simply plugging in one’s earphones without worrying about standing out; thus, it is quite non-stigmatizing.
Isha Puntambekar
