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cording to Titchener, for about six seconds.^[1] "All impressions within this period of time are present to us at once. This makes it possible for us to perceive changes and events as well as stationary objects. The perceptual present is supplemented by the ideational present. Through the combination of perceptions with memory images, entire days, months, and even years of the past are brought together into the present."

In this ideational present, vividness, as James said, is proportionate to the number of discriminations we perceive within it. Thus a vacation in which we were bored with nothing to do passes slowly while we are in it, but seems very short in memory. Great activity kills time rapidly, but in memory its duration is long. On the relation between the amount we discriminate and our time perspective James has an interesting passage:^[2]

"We have every reason to think that creatures may possibly differ enormously in the amounts of duration which they intuitively feel, and in the fineness of the events that may fill it. Von Baer has indulged in some interesting computations of the effect of such differences in changing the aspect of Nature. Suppose we were able, within the length of a second, to note 10,000 events distinctly, instead of barely 10 as now;^[3] if our life were then destined to hold the same number of impressions, it might be 1000 times as short. We should live less than a month, and personally know nothing of the change of

1. Cited by Warren, Human Psychology, p. 255.
2. Op. cit., Vol. I, p. 639.
3. In the moving picture this effect is admirably produced by the ultra-rapid camera.