I argued that these panels force a reader to make an inference about the missing information (in this case Snoopy getting hit by football players), and that these images also play a narrative role in the sequence—they are narrative climaxes. Because this inference omits information within this panel, it is different than the type of "closure" proposed by McCloud to take place between the panels. Rather, you need to get to the last panel to figure out what happened in the one prior, not what happens between panels 3 and 4.
So, to test this back 7 years ago, I ran a few experiments...
At long last, those studies are now published in my new paper, "Action starring narrative and events" in the Journal of Cognitive Psychology. Though McCloud placed inference as one of the most important parts of sequential image understanding over 20 years ago, and this has been stressed in most all theories of comics, this is one of the first papers to explore inference with actual experiments. I know of a few more papers that will be following too, both by me and others. Exciting!
You can find the paper along with all of my other downloadable papers, or you can check it out directly here (pdf).
Here's the full abstract:
Studies of discourse have long placed focus on the inference generated by information that is not overtly expressed, and theories of visual narrative comprehension similarly focused on the inference generated between juxtaposed panels. Within the visual language of comics, star-shaped “flashes” commonly signify impacts, but can be enlarged to the size of a whole panel that can omit all other representational information. These “action star” panels depict a narrative culmination (a “Peak”), but have content which readers must infer, thereby posing a challenge to theories of inference generation in visual narratives that focus only on the semantic changes between juxtaposed images. This paper shows that action stars demand more inference than depicted events, and that they are more coherent in narrative sequences than scrambled sequences (Experiment 1). In addition, action stars play a felicitous narrative role in the sequence (Experiment 2). Together, these results suggest that visual narratives use conventionalized depictions that demand the generation of inferences while retaining narrative coherence of a visual sequence.
Cohn, Neil, and Eva Wittenberg. 2015. Action starring narratives and events: Structure and inference in visual narrative comprehension. Journal of Cognitive Psychology.