In the first experiment, they varied the length of time that each panel stayed on screen, 83 milliseconds (ms) and 150ms, with a constant ISI of 300ms between each exposure. They found that the responses to whether the sequence was in correct or incorrect order varied per speed. Panels at 83ms were only correctly responded to 24% of the time, while those at 150ms were correctly responded to 71% of the time. They conclude that 150ms is the minimum time necessary for exposure.
Experiment 2 varied ISI—the time between each panel—keeping each panel exposed on screen for 150ms. They found that accuracy increased as ISI increased. At 133ms, accuracy reached around 70%, staying constant through 217ms and 300ms. They thus conclude that an ISI of more than 130ms is necessary.
I actually find these numbers to be blazing fast. In my experiments, we used a consistent ISI of 300ms to avoid the effect of panels seeming like they turned into a flipbook style animation. In self-paced reading, the speed of processing panels depended on both the complexity of the panel and its context in the sequence, but people would often average between 700ms or 1 second for reading each panel. In our measure of brainwaves—which are even more sensitive to the timing of the brain's comprehension—we don't fully get a response for activation of recognizing something is awry in meaningful information until starting around 200ms to 250ms at the very soonest.
Thus, I find it highly surprising that an exposure time of 150ms and an ISI of 130ms would be sufficient to get as accurate responses as they did. I would think that these numbers would be the absolute minimum amount of time necessary, and that these numbers may get larger if the panels were more complex (their stimuli looked even more simple than the Peanuts panels we use in our experiments).
Inui, Toshio, & Miyamoto, Kensaku (1981). The time needed to judge the order of a meaningful string of pictures Journal of Experimental Psychology: Human Learning and Memory, 7 (5), 393-396 DOI: 10.1037//0278-73220.127.116.113