A tachistoscope is a device that displays a
picture
An image or picture is a visual representation. An image can be two-dimensional, such as a drawing, painting, or photograph, or three-dimensional, such as a carving or sculpture. Images may be displayed through other media, including a proje ...
,
text
Text may refer to:
Written word
* Text (literary theory)
In literary theory, a text is any object that can be "read", whether this object is a work of literature, a street sign, an arrangement of buildings on a city block, or styles of clothi ...
, or an object for a specific amount of time. It can be used for various purposes such as to increase recognition speed, to show something too fast to be consciously recognized, or to test which elements of a display are memorable.
Early tachistoscopes were mechanical, using a flat masking screen containing a window. The screen concealed the picture or text until the screen moved, at a known speed, the window over the picture or text, revealing it. The screen continued to move until it hid the picture or text again. Later tachistoscopes used a
shutter system typical of a
camera
A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
in conjunction with a
slide or
transparency projector. Even later, tachistoscopes used brief illumination, such as from fast-onset and fast-offset
fluorescent lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor ...
s, of the material to be displayed. By the late 1990s, tachistoscopes had largely been replaced by computers for displaying pictures and text.
History
The first tachistoscope was originally described by the German physiologist
A.W. Volkmann in 1859.
Samuel Renshaw used it during
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
in the training of fighter pilots to help them identify aircraft silhouettes as friend or foe.
Applications
Before
computers
A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...
became universal, tachistoscopes were used extensively in
psychological research
Psychological research refers to research that psychologists conduct for systematic study and for analysis of the experiences and behaviors of individuals or groups. Their research can have educational, occupational and clinical application ...
to present visual stimuli for controlled durations. Some experiments employed pairs of tachistoscopes so that an experimental participant could be given different stimulation in each
visual field
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it i ...
.
Tachistoscopes were used during the late 1960s in public schools as an aid to increased reading comprehension for
speed reading. There were two types: the student would look through a lens similar to an aircraft bombsight viewfinder and read letters, words, and phrases using manually advanced slide film. The second type projected words and phrases on a screen in sequence. Both types were followed up with comprehension and vocabulary testing.
[Brown, James I]
"Teaching Reading With the Tachistoscope"
''Journal of Developmental Reading'', Winter, 1958, 1(2)8–18
Tachistoscopes continue to be used in market research, where they are typically used to compare the visual impact, or memorability of marketing materials or packaging designs. Tachistoscopes used for this purpose still typically employ slide projectors rather than computer monitors, due to
* the increased fidelity of the image which can be displayed in this way and
* the opportunity to show large or life-size images.
References
{{Reflist
External links
* https://web.archive.org/web/20220328115006/http://www.sykronix.com/researching/tscope.htm How to Build and Use a Tachistoscope]
Photography equipment
Optical devices