Engineering Psychology · UTSIC
An instrument consisting primarily of pair of sturdy PLATO spectacles and a PLATO driving circuit in a small black enclosure.
A pair of spectacles with frames of beige textured plastic with a black felt inner lining. The spectacles are of sufficient size to fit over a pair of prescription glasses. The lenses of the spectacles are opaque white screens (liquid crystal cells) an electrical cord emerges from the left temple. This cord is terminated in a 3.5mm minijack connector that plugs into the driving circuit enclosure.
The driving circuit enclosure has two jacks and three switches on one side. A metal clip on one face allows for the enclosure to be worn by the user. A black electrical cord , terminated in a small 9-volt transformer plug, is attached to one side of the instrument.
Accession Number: 2024.ep.27
Liquid-Crystal Tachistoscope; Visual Occlusion Glasses
Primary Materials: Plastic, Glass.
Stamped on the top surface of the glasses: “O8A451”
Printed in white pigment on one face of the driving circuit enclosure: “TRANSLUCENT// TECHNOLOGIES// Inc.// PLATO Model: P-1”
Written on a masking tape lablel pasted opposite the socket for control cord from the glasses: “R L”
Printed in white pigment a clear adhesive label fixed to one side of the enclosure: “TRANSLUCENT TECHNOLOGIES// On loan to// Garry Beekenkamp”
Goggles only: Height = 6 cm, Width =16cm, Length= 16.
This instrument was designed to be used in psychological experimentation that require the user’s field of vision to be blocked (occluded) in a time-precise manner. When activated, the liquid crystal lenses switch from transparent to opaque, allowing researchers to control when a subject can see while performing a task. This instrument is typically used in cognitive, driving, and reaction-time tests.
The goggles are functional and in good cosmetic condition. There is some scuffing on the driving circuit enclosure.
Associated Instruments:
Manufacturer: Translucent Technologies Inc., Canada
Date of Manufacture: c. 1990s – early 2000s.
This item was among a small collection of items related to the development of the PLATO visual occlusion goggles donated to the collection by Dr. Paul Milgram on September 11, 2024.
John W. Senders, Kristofferson A. B., Levison W. H., Dietrich C. W., Ward J. L. (1967). The attentional demand of automobile driving. Highway Research Record, 195, 15–32. (Archived March 5. 2025).
Paul Milgram and R Van der Horst. “Alternating-Field Stereoscopic Displays Using Light-Scattering Liquid Crystal Spectacles.” Displays 7, no. 2 (1986): 67–72.
The PLATO (Portable Liquid crystal Apparatus for Tachistoscopic Occlusion) system was developed beginning around 1981 by Professor Paul Milgram. The system is an experimental tool that permits the time controlled occlusion of one or both of a subject’s eyes. The system has various applications, including research in visual perception, neuroscience, sports psychology/training, ergonomic evaluation of interfaces, etc., in addition to its original goal for quantifying the attentional workload of various tasks
Visual occlusion was pioneered by Dr. John Senders and collaborators in the 1960’s (cited and linked above). Milgram completed his PhD under Senders at UofT in 1980. During his post-doc research, he focused on driving tasks, as Senders had done. This research was done while working at the Institute for Perception of the Dutch Organization for Applied Scientific Research (subsequently TNO Human Factors) in Soesterberg, the Netherlands.
At that point, visual occlusion research relied on head mounted mechanical visors, first developed by Senders, to periodically block vision. While at TNO, Milgram developed a goggle-based system using cholesteric liquid crystals to block vision. This was proposed as an alternative to existing twisted-nematic liquid crystal devices and PLZT ceramic-based shutters. In addition to the need for light polarising layers, which significantly reduced the intensity of light transmitted, the former had a relatively slow refresh rate while the latter required very high voltages.
Milgram returned to Toronto in 1986 to take a faculty position at the Department of Industrial Engineering (currently Mechanical and Industrial Engineering) of the University of Toronto. In 1990, in Toronto, he founded Translucent Technologies Inc., which continues to develop and sell the PLATO system worldwide.