What effect does this kind of speaker have in this novel?
De Lillo's Falling Man uses three points of view to convey the narrative of the novel. The first is that of main character Keith Neudecker, who is a 9-11 survivor. The other perspective comes from Lianne, a woman who is struggling with an Alzheimer's stricken mother. Both characters are struggling with emotions such as guilt, fear, and overall uncertainty. This is the reason why De Lillo takes so much creative license in the use of stops, commas, ellipses, and overall shifts in setting and mood.
Several effects occur as a result of these shifts. The reader becomes just as anxious, confused and unsteady as the character. It is part of the cathartic experience of trying to understand what goes on in the mind of a survivor.
For once, the characters' consistently need to regroup their thoughts. They also have a tendency to seek refuge either mentally or physically. An example is Keith's visits to Florence, and Lianne's visits to her mother at the home. When the characters undergo these changes, the narrative also changes entirely, bringing complete thoughts to full stops, then shifting to another thought, and then ending up in another setting altogether.
The creative license applies to all punctuation for example:
this was the man who would not submit to her need for probing intimacy, overintimacy, the urge to ask, examine, delve, draw things out, trade secrets, tell everything. it was a need that had the body in it, hands, feet, genitals, scummy odors, clotted dirt, even if it was all talk or sleepy murmur.
Therefore the ultimate purpose is to bring the reader into the plot and have the reader blend his or her own weaknesses, anxieties, fears, and other human emotions with those of the characters.