Flicker-induced Hallucinations

Throughout the ages, people have spontaneously noticed that they can induce hallucinatory experiences by exposing themselves to flickering lights. One method for inducing these experiences before electricity was to rapidly wave one's hand with fingers spread apart in front of one's face while looking at the sky. Beatniks in the 1950s, such as William Burroughs and Brion Gysin, explored flickering lights as a way to create hallucinatory experiences without psychedelic drugs (ter Meulen, Tavy, & Jacobs, 2009; Schwartzman et al., 2019). Brion Gysin and Ian Sommerville invented the Dreamachine by placing a lightbulb surrounded by a cylinder with holes on a spinning turntable (Gysin & Wilson, 1985). Typically, people would face the Dreamachine with their eyes shut, making it a rare work of visual art that one is expected to experience with closed rather than open eyes! The Dreamachine is similar to adjustable rate stroboscopes used in psychology laboratories. Flickering lights at a rate of 8-12 hertz (e.g. 8-12 flickers per second) often leads to people to report seeing radiating lines, circles, webs, dots, or even entire forms such as a spider or face (Adrian & Mathews, 1934). The 8-12 Hz frequency band corresponds to the alpha waves in the brain - broad and synchronized neural oscillations of electrical activity, often times prominent when a person is in a relaxed state. While you might think that people exposed to light flickering at 8-12 Hz would show heightened alpha wave brain oscillations, in fact, some results have suggested exactly the opposite (Bartossek et al., 2020), with 8-12 Hz flickering causing alpha wave brain activity to be reduced and an increased diversity of different frequencies of neural oscillation (Schwartzman et al., 2019).

This program allows you to explore your own visual experiences with a flexible Dreamachine. You can change the frequency with which two colors flicker, as well as the colors themselves. You set the two colors by mixing their Red (R), Green (G), and Blue (B) values. Black would be created by setting all three sliders for a color to 0, and white is created by setting all three sliders to 255. You adjust the rate of flicker by adjusting the "frame time" slider.

Binaural Beats

When two pure tones are played, a person will hear a periodic oscillation, or beat, that corresponds to the difference in frequency between the tones. For example, if a 150 hertz (e.g. 150 cycles per second) tone is played to a person's left ear while a 152 hz tone is played to the right ear, then the person will hear an oscillating warble that beats with a frequency of 152-150=2 hz. These binaural beats allow people to hear oscillations that are too slow to be heard as simple tones. The lowest pure tone a human can hear is around 20 hz. If a simple loop repeat a click 20 times per second, people will hear it as a very low tone, but if the loop is played slower than that, people will hear it as stream of clicks. You can try this out for yourself with this app by setting one tone frequency to 0 hz (no tone at all) and the other to 10 hz (you should hear a rapid stream of clicks), then 30 hz (you should hear a very low tone). With binaural beats, one can have an auditory experience of periodic oscillation slower than 20 hz. Furthermore, if one tone is played to the left ear while the other is played to the right ear, we can make sure that the beat frequency between the two tones is not heard by either individual ear, but rather is only heard centrally, in a part of the brain that integrates the auditory input from the two ears. Practically speaking, this means that if you want to make sure that the binaural beats you hear are a central brain experience rather than possibly occurring in a single ear, you should wear headphones or earbuds when listening to the tones produced in this app.

Why would you want to hear an auditory oscillation slower than 20 hz? One reason is to possibly affect your brain's rhythms. There are several different brain rhythms that have been claimed to have cognitive correlates:


When binaural beats are heard by humans, oscillations synchronized to the beat frequency are detectable in the medial superior olive in the brainstem and the inferior colliculus of the midbrain (Draganova et al., 2008). One might intuitively think that binaural beats at a frequency of 10 hz might lead to more prominent Alpha rhythms in the brain. In fact, some research has suggested the opposite -- 10 hz binaural beats lead to decreased alpha and beta power and increased theta power (Kasprzak, 2011), paralleling the result mentioned above for stroboscopic stimulation. Researchers have been intrigued by the possibility that cognitive or emotional states might be affected by interventions such as stroboscopic stimulation or binaural beats (Herrmann et al, 2016). If neural oscillatory activity is entrained to binaural beats, then presenting different binaural beats to a person might affect their mental state (Huang and Charyton, 2008). The potential for binaural beats to non-invasively alter brain rhythms and possibly mental state has been pursued with excitement (Vernon, 2009). Some studies have found that presenting binaural beats in the Gamma frequency range can affect divergent thinking (Reedijk et al., 2013) and control of attention (Reedijk et al., 2015), while Beta frequency binaural beats improve performance in cognitive tasks related to working memory and executive function (Kennedy, 1996). However, other studies have failed to replicate these results or find cognitive advantages to binaural stimulation (Goodin et al., 2012; López-Caballero & Escara, 2017). It is probably too early to determine whether binaural beats can have reliable cognitive, affective, or therapeutic benefits. With this in mind, perhaps you can help generate more data!

Things to Try

This app combines together oscillatory stroboscopic and auditory stimulation. It allows you to explore visually induced hallucinations, cognitive and affective impacts of binaural beats, and their combination. I hope that you get inspired to explore your experiences, in either a qualitative or quantitative fashion. And if you do, I hope that you will submit a report of what your experience was by pressing the "submit your impressions" button.

References



Designed and programmed by Robert Goldstone (rgoldsto@indiana.edu). Visit our Percepts and Concepts Laboratory housed within the Cognitive Science Program and Department of Psychological and Brain Sciences at Indiana University