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Recognizing letters embedded in other letters is difficult. Framing (boxing) a symbol is thought to make it more conspicuous or easier to distinguish from the background. However, the frame may actually affect the legibility of the symbol adversely. This study evaluates the effects of spatial arrangement and framing on display legibility. One general characteristic of vision is that surrounding objects affect the perception of a central object. This is known as the crowding effect and is a type of spatial-frequency masking effect. We measured the minimum visual acuity required to distinguish crowded symbols by using the low-pass filtering method and the multi-frame detection task. The results showed that a framed symbol is less legible than an isolated symbol, and that the crowding effect is a function of distance between the symbol and a mask, and of contrast of the mask. The spatial spread of the effect was evaluated quantitatively.