"When a student has a delay in the developmental visual perceptual skill of visual figure ground, they may not be able to space the letters within words adequately. First graders whose letters vary widely in size may not be aware of how their work differs from the model because of delays in the development of their visual processing skills. Students who put extra wide gaps between letters within words or between words within a line may also be attempting to cope with an underdeveloped set of visual perceptual skills."
Can Too! Read: Oddly spaced handwriting could indicate a visual
perceptual developmental delay: