Abstract: Three experiments were conducted to investigate: 1) the relationship between visual duration threshold (VDT) and the size and brightness of stimulus; 2) VDT of words, phrases and disconnected word-groups; 3) VDT of familiar and unfamiliar words under different procedures.The results indicated: 1) under brief exposures (below 20 ms.), size×brightness×VDTk; 2) the VDT difference is significant between single word and disconnected word group (2—4 words) but not significant between single word and phrase (2—4 words); 3) VDT for familiar words are all about 10 ms. under different procedures (recognition or reproduction); 4) VDT difference between familiar and unfamiliar words is highly significant.

Key words: NULL