Humans at any given moment process probably millions of pieces of information. As I sit here typing this, I see other people, carpets, various books, different shades on lighting on the cabinets, my hand, and well, basically the list seems endless. When you throw in that all this information merges in our brain with every piece of information it has retained in the past, and with the implications of this for our future actions, that is a whole mess of information being processed. And yet, in the end, the vast majority of us function fairly well.
Underlying the capacity to function amidst such an incredibly large amount of information being processed is a basic ability to make sense of what we know, what we are seeing, and what we are feeling, as well as attempting to address those same issues in others. In short, we have an incredible need to be able to make sense of the world around us as it enters our brain.
A theory called The Meaning Maintenance Model (originally formulated by Steven Heine of the University of British Columbia and colleagues) has assessed and measured the effects of this need for coherence. In short, this theory argues that anything that is unexpected - that is - that disrupts our natural way of thinking (our schemas), causes a deficit in our "meaning maintenance" that must, in turn, be restored.
For instance, imagine that you are in a study and the experimenter may have been switched but may not have. You cannot really tell. Or imagine that you are asked to think about something you have never experienced, like death. Or imagine that you are reading a story and you get to the end, and well, there is no ending. All of these experiences have been found in studies based on The Meaning Maintenance Model to elicit a heightened need for sense making and meaning pursuit.
For instance, these (often) benign threats to our coherence (sense-making) have been found to have some rather interesting effects, such as increasing the desired punishment of a person breaking the law (in one study, a prostitute). In another study, people following a coherence threat were better at learning a novel grammar task, and in yet another study, people who were exposed to non-sense later showed a heightened desire for clear, well structured information.
Put perhaps more succintly, we all have a basic need to make sense of the world around us. And, when this is challenged, even by something as benign as an experimenter maybe switching on us, or reading a story with no ending, we respond to this deficit in "sense" by heightening our efforts - compensating - to make sense of the world, even in unrelated domains.
And this is how reading a story with no ending makes people more hostile towards a prostitute.