Visual Persistence Survey (explanation below)
Warning - Flickering Images. Use your judgement and caution if you are disturbed by flickering images.

20 ms
40 ms
80 ms
120 ms
160 ms
200 ms
240 ms
280 ms
320 ms
380 ms
40 ms


If you find any of these colour combinations particularly good or bad, click the buttons beneath that display.

good bad
good bad
good bad
good bad
good bad
good bad

The object of this exercise is to find out how much the speed of human word and number perception varies, and how that affects reading comfort and choice of career. Specifically -

how long does the image of a number or a word have to be displayed, in order for you to see it clearly,

This visual persistance tester was originally created as part of an on-line survey MA research project, to collect global data about the relationship between visual persistence duration (VP) (see below) and reading speed.

The research questions are;

What is the distribution of VP in the human population?

Is VP duration correlated with reading speed, difficulty, first written language or age?

Is VP duration correlated with choice of work / profession?

Is VP duration effected by colour contrasts?

Visual Persistence is a feature of our perceptual system. Visual images (letters of the alphabet for example), persists in our visual system for around 40 - 300 milliseconds after the stimulus is removed from view. Some people have a fast image decay time and others hold images for longer. When we are presented with a rapid sequence of images (such as when reading or tracking movement) a backlog of persisting images can build up, resulting in multiple images persisting simultaneously. The brain reacts by paying more attention to some of the conflicting images and ignoring or delaying the perception of others.

This phenomenon (one image being prioritized over another) is often called 'masking' in the literature and may result in a range of perceptual distortions and deletions - letters appearing to move about or change position, reversals, parts of words or letters missing, etc. We (Snakes and Ladders Charitable Trust) have found that all our 'dyslexic' students have a VP speed near the longer end of this natural range, (and read relatively slowly) and that all our teaching staff have VP speeds near the shorter end of the range, and can read very fast. This raises the question of whether people's choice of occupation may be effected by their visual persistence.

If you can spare a few minutes to take part in this anonymous survey - this is what we would like you to do.

Click either of the 'START. . . ' buttons at the top of the page. This displays a sequence of either numbers or words. You can control the speed of the displays by clicking on the two rows of radio buttons above the display - these control the time delays in milliseconds (ms). The second row controls the duration of each image display. The top row controls the time gap between each image display. You can stop the display at any time with the 'Stop Displays' button. You can then restart either display.

Please take a note of the shortest gap duration in ms at which you are perfectly comfortable reading the words and numbers. Please try to resist the temptation to report that you can read the images faster than you actually can :-)

The displays use a range of different foreground and background colours. Please notice if any of these colour combinations are particularly good or bad for your visual system.

There was originally a report form collecting results in an anonymous database. This is no longer active.