Expecting a Surprise? The Effect of Expectations on Perceived Surprise in Stories

Expecting a Surprise? The Effect of Expectations on Perceived Surprise in Stories Rebecca Grimes-Maguire (rebecca.grimes@ucd.ie) Mark T. Keane (mark.keane@ucd.ie) Department of Computer Science, University College Dublin Belfield, Dublin 4, Ireland the relationship between expectation and surprise is not quite so clear-cut. We examine the hypothesis that a surprising event is unexpected relative to a reader’s mental representation of the sequence. In other words, when reading a story, a person’s level of surprise should be determined by whether or not the specific conditions supporting the surprising event were built into their representation as the prior narrative was comprehended. Abstract This paper describes two novel experiments that investigate the cognitive basis of surprise in stories depicting simple, everyday events. Participants were asked to read a number of short scenarios, each of which concluded with some surprise event for the central protagonist. The story versions differed in how strongly they predicted this ‘surprise’ conclusion, by varying the degree of attention drawn to key enabling conditions for that conclusion. The effect of this manipulation on participants’ surprise ratings, and the speed with which they read the final sentence, were used as dependent measures. The results of our experiments show that the specific representations built by people in understanding the earlier part of a story have definite effects on their level of surprise at later events. Furthermore, the pattern of reading times for the target sentences supports the explanation given for these differences. We discuss the consistency of these findings with theories of discourse comprehension and describe how such effects might be modelled computationally. Surprise and Expectations At a cognitive level, surprise is intuitively related to expectations, and as such the Oxford English dictionary defines it as “an unexpected occurrence or event”. However, this may not be a straightforward relationship due to differing interpretations of what it means to expect something. Teigen & Keren (2003) observe that in cognitive psychology, expectations are usually quantified in terms of probabilities; i.e. an unexpected event is considered to be a low probability outcome. Yet, events that have an equal likelihood of occurring are not always judged to be equally surprising by an observer (e.g. Schackle, 1969). Surprise then, might not be due to the low probability of an outcome, but to its degree of contrast with a more likely, but disconfirmed, expectation. The Expectancy-Disconfirmation hypothesis, (Meyer Reisenzein & Schutzwohl, 1997), similarly suggests that surprise is experienced when expectations based on preexisting schemas fail to be confirmed. If we apply these ideas to the area of discourse comprehension, then surprise is likely to occur when a predicted sequence of events in a story is violated or deviated from in a significant way. While little research has investigated the conditions which evoke surprise in narrative, a lot of work has examined people’s ability to form forward inferences during reading (e.g., Klin et al., 1999; McKoon & Ratcliff, 1986). These inferences operate by linking representations of the text with background knowledge to predict a likely outcome, thus facilitating the comprehension process. It seems feasible that when people read a familiar event sequence in a story, they are able to make predictions about what will happen next. According to Schank & Abelson (1977), this is done by means of script-based schemas. For example, when reading the scenario “The cup of coffee was balanced on the arm of the chair. Suddenly, Richard sneezed. ”, most people can predict that Richard’s sneeze will cause the cup of coffee to spill or be knocked off the chair. If the reader subsequently discovers that a cat on Richard’s knee jumps up and scratches him, they will probably be surprised at this ending, as, despite Keywords: Discourse Comprehension; Surprise; Expectation. Introduction As well as being one of the most basic and universal of emotions, surprise has long been recognised as a fundamental building block of human cognition (Darwin, 1872; Ekman, 1972). Despite this, cognitive investigations of surprise, which move beyond the physiological and affective domain, have only recently emerged (e.g. Fisk, 2002; Schutzwohl, 1998; Teigen & Keren, 2003). The occurrence of surprise in narrative comprehension presents a good starting point for tackling this complex phenomenon, as it is undoubtedly an important and central aspect of many stories. Surprise, for instance, has been shown to be vital in determining the perceived interestingness of a piece of text (e.g. Iran-Nejad, 1987; Kim, 1999); very few best-sellers describe the hero going to the office, working all day and then coming home and going to bed. Instead, writers often maintain a reader’s interest with well-timed surprises; for instance, Raymond Chandler’s murder discovery scenes often describe the dead body obliquely (e.g., a brown loafer protruding from the curtain), so that the reader’s surprise at discovering the referent (i.e., that the shoe is attached to a corpse) mirrors the detective’s surprise at discovering the body. In this paper, we try to elucidate the cognitive basis of surprise in understanding narrative. Evidently, a person should be surprised when something unexpected occurs in an event sequence. However, as discussed in the next section,