The flanking letters provide information about the width of the target letter. For low-pass filtered Times, the enhancement due to flanking letters is diminished. Effect of filtering To simulate letter recognition near the acuity limit, we low-pass filtered the fonts. There is little difference between the normal fonts. Information transmitted by the Random-dot Fixed Size font is greatly reduced relative to the other fonts.
Braille transmits the most information.
The amount of information transmitted by a font deteriorates as it becomes more blurred. The variation in information transmitted by different fonts is also reduced. The amount of task-relevant information of a stimulus can be meaningfully measured by studying the behavior of an ideal observer. The mutual information between the response of the ideal observer and the true identity is used to quantify the information content of the stimulus. We observed several non-obvious results regarding fonts and letter recognition using this information measurement.