[How do we remember when and where?]

The short-term retention of temporal order and that of spatial position were compared using six types of materials. They were three types of letters: (a) Hiragana (phonetically one syllable), (b) Kanji-1 (one syllable), (c) Kanji-2 (two syllables, and three types of non-verbal materials: (d) two-digit numeral, (e) musical note, (f) non-sense figure. Eight stimuli of each type were presented visually to 40 female subjects. It was shown that the performance changed with the types of materials in both retention tasks and that for some materials the retention of temporal order was better than that of spatial position, and for others, vice versa. In the temporal tasks, Hiragana attained the highest score, Kanji-1 the second and Kanji-2 the third. In contrast, the scores were reversed in the spatial tasks. The results suggested that the number of syllables was one of the important factors in temporal memory, though not necessarily in spatial one. The effect of other more subtle factors on retention such as visual tracking of temporal order and imprinting of visual image on the position of presentation was discussed.