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Head-Mounted Eye-Marker Camera

Engineering Psychology

An instrumented helmet (2023.ep.23.1) is set on a wooden mount (2023.ep.23.2).

The instrumented helmet consists of a white plastic helmet with a black instrument attached to it at its top. The helmet has a headband with a ratchet adjustment at the back. There is a black band along the rim of the helmet. A similar band marks the centre line of the helmet.

The instrument at the top of the hat consists primarily of an 8mm camera. Part of the cover is missing, revealing the inner workings of the camera, including a single empty film spool. A small electrical motor is visible inside the case with wiring leading to a four-pin electrical socket on one side of the camera. A second optical element, containing a beam splitting prism, is mounted in front of the camera. This consists primarily of a forward-looking lens and a periscope descending at right angles to this lens that ends in an eyepiece suspended in front of the wearer’s eye. A viewfinder window on one side of this optical element is used to calibrate the instrument.

The instrument can be adjusted relative to the helmet using an x/y stage that forms the mount between helmet and instrument. The height of the eyepiece can be adjusted using a rack and pinion mechanism.

The mount consists of a plywood base supporting a large wooden plug that has been shaped to fit the helmet. This mount was presumably made to support the helmet when the instrument was not in use.

Accession Number: 2023.ep.23.1-2

Alternative Name:

Eye tracking instrument

Primary Materials: Wood, Plastic, Iron Alloy.


Dimensions (cm):

(Helmet set on base) Height = 42, Width = 22, Length = 32.


This artifact was used to record the movements of a subject’s eyes by superimposing a recording of a point reflected off the surface of a subject’s iris onto a recording of the overall view as captured by a camera mounted to a subject’s head.

Using this technique, the subject’s attention to a particular image or task could be measured and quantified.


This artifact appears to be largely intact. The white surface of the helmet is marked and scuffed in places. A number of the fasteners have superficial rust. The cover of the camera is missing. Two electrical wires are disconnected: one black wire leading from the body of the camera, one green wire leading from a small lamp on the eyepiece.

Associated Instruments:


The manufacturer of this instrument hasn’t yet been determined. Its development was funded by the Minister of National Defence of Canada. It was likely built in a related workshop.

Date of Manufacture: c. 1968


This artifact was designed in the early 1960s by Norman H. Mackworth and E. Llewellyn Thomas for the Toronto-based Defense Research Medical Laboratory (DRML) and used in numerous subsequent studies.

It was acquired from Dr. Paul Milgram, emeritus professor at the University of Toronto Department of Mechanical and Industrial Engineering, on August 29th, 2023.

Additional Information and References:

Jane F. Mackworth and Norman H. Mackworth “Eye Fixations Recorded on Changing Visual Scenes by the Television Eye-Marker.” Journal of the Optical Society of America 48, no. 7 (1958): 439–45.

Norman H. Mackworth , and E. Llewellyn Thomas. “Head-Mounted Eye-Marker Camera.” Journal of the Optical Society of America 52, no. 6 (1962): 713–16.

Norman H. Mackworth , and E. Llewellyn Thomas. Optical eye marker head camera. Canadian Patent CA675906A, assigned to Minister of National Defence of Canada. granted 1963-12-10.

E. Llewellyn Thomas. “Eye Movements and Fixations During Initial Viewing of Rorschach Cards.” Journal of Projective Techniques & Personality Assessment 27, no. 3 (1963): 345–53.

Thomas, E. Llewellyn. “Movements of the Eye.Scientific American. Vol. 219. United States, 1968.

Historical Notes:

Human visual perception involves frequent eye movement; The mental understanding of the visual field is created by visually scanning the subject of attention so that the relatively narrow area of human visual focus surveys areas of importance in order to construct an overall mental impression.

Likewise, one way to explore how people perceive particular subjects—to understand what aspects of a subject are subjectively important—is to trace the movement of the eyes. Eye movements can be quantified in a number of ways, from the frequency, direction, distance, speed, and overall pattern of movements (saccade), to the length of time that focus is held on a particular area.

One method of measuring this phenomenon is using a technique called “corneal reflection” in which a light source is used to reflect a point of light off the surface of the cornea. The reflected point of light reveals the point on the scent that the subject is looking at. The technique was first explored in detail by American experimental psychologist Raymond Dodge (1871–1942) in the first decade of the 20th century.

This artifact originates in the work of two English psychologists, Jane F. Mackworth & Norman H. Mackworth, who developed an eye tracking system while working at the Applied Psychology Research Unit of the UK Medical Research Council in Cambridge, England (Mackworth and Mackworth, 1958). This was a stationary apparatus with the experimental subject seated before a display monitor that displayed a scene.

The Head-Mounted Eye-Marker Camera was an evolution of that earlier system. It was developed by Norman H. Mackworth and the English-born Canadian physician and engineer, Edward Llewellyn-Thomas (1918-1984) for the Toronto-based Defence Research Medical Laboratory (DRML). By placing a lightweight camera on the subject’s head, the technique could be applied to a greater variety of subjects than the stationary video-based system. This head-mounted apparatus was first described in Mackworth and Thomas 1962. The developer’s describe the instrument as follows in that document: “The head-mounted eye-marker camera is primarily a portable field instrument. In no sense can it be called a very precise instrument, although its accuracy is sufficient for many problems. When desired, better registration and definition can be obtained by mounting the same camera on a stand and preventing head movements.” (Mackworth and Thomas 1962, 713.)

This apparatus was used in a broad range of experiments over the subsequent decades. These ranged from psychological studies involving, for instance, the viewing of photographs of people or images of Rorschach cards, to engineering studies of subjects operating machines such as automobiles and light planes. The later was of particular relevance to the DRML, which funded the machine’s development; the study and development of safe and efficient human-machine interfaces was a major defence occupation over the Cold War Period which saw the emergence of new and complex machines, such as helicopters and turbojet aircraft, and space habitations.

This apparatus was described in the August 1968 issue of Scientific American, and was featured in an illustration on the issue’s cover.

It isn’t clear when this particular artifact was created. The various publications that describe its use show an evolving instrument. For instance, in the earliest descriptions of the instrument, stability was established using a bite bar passing through the subject’s mouth. This artifact represents a later version that is depicted in the Scientific American article. The subject probably wore a thick toque or watch cap, and the helmet was stabilized by tightening it down against this surface. It isn’t clear whether these various versions represent several instruments, modifications to a single instrument, or some combination of the two.