In the spring of 2009, Robert Carlsen and I worked on mapping visual stimuli to physical movement in this project called BlindSight. Our goal was to explore synesthesia -- if flashing lights close to the eye at high frequencies causes visual patterns to appear for the viewer, what happens if we associate different visual patterns with specific body positions?

WHAT IT IS

BlindSight is a wearable system for inducing visual hallucinations through strobing light patterns and controlling them with physical movement. This idea is similar to Mitch Altman’s Sound and Light Machine (aka. the Brainwave Glasses) that are described in Make: Volume 10.

HOW IT WORKS

There are two parts in the Blindsight system: the glasses, and the sleeves.

The glasses consists of dark sunglasses with an RGB LED in the center of each lens. Each LED is mounted through through a hole, and when the glasses are worn, the LEDs sit a few centimeters from the eye.

The sleeves are a set of sleeves made from a stretchy Lycra-like material and attached together by nylon webbing. Similar to a shrug, they were designed and built by me to fit as wide a range of people as possible; since this experience is very difficult to describe, we wanted as many people as possible to be able to try it. There is a control unit attached to the back of the sleeves and wired to the glasses. With batteries and several switches, this allows us to control the blinking of the LEDs and to experiment with the patterns the user is experiencing.

BACKGROUND

In the September 2008 edition of the journal Cortex, Dominic H. ffytche describes a study which employed flashing goggles to induce visual hallucinations for the purpose of analyzing brain activity with MRI. The study indicates that flashing frequencies between 5-30Hz at a certain intensity caused participants to describe perceiving hallucinations (Purkinje patterns) and produced a measurable change in the brain activity.

Although the patterns may differ for each viewer, they seem to be the consistent for the viewer at a given frequency. Based on this observation, we hoped to create a relationship between the user’s body movements and the corresponding changes in visual hallucinations. The ideal scenario would be to enable a user to generate an association between certain Purkinje patterns and the orientation of the body relative to itself, thus representing a small portion of our sense of proprioception.

As we experimented to determine the levels of discernible patterns within the available frequency range, we thought it best to limit our focus to the upper body for this prototype – and possibly the arms alone. There are many unknowns in this sort of visual stimuli, and limiting the movement allowed us to explore the range of movements that can be incorporated into a system like this. We also experimented with various sensors and inputs – flex sensors and tilt switches were favorites – to determine how best to map arm movements to particular frequencies (and therefore particular hallucinations).