On the basis of the verbal loop hypothesis, specific changes in the shape of the perceptual serial position curve were predicted as a function of encoding, or verbalization length of the stimulus, and stimulus exposure time. The effects of post-stimulus delay, both with and without an interpolated task, were also explored. With eight-place binary numbers as stimuli, a group of 12 Ss was tested to evaluate the effect of these four variables—verbalization length, exposure time, delay time, and interpolated task during the delay. It was demonstrated that, as predicted, increasing the verbalization length and shortening the exposure time have similar effects. They tilt the serial position curve up on the right. The presence of an interpolated task produces an overall increase without, however, any effect on the shape of the serial position curve. Poststimulus delay, within the range used in this study, produces no clear or systematic effect.