El curso temporal de la negaciónprocesamiento y representación

  1. Isabel Orenes Casanova
Supervised by:
  1. Carlos Santamaría Moreno Director

Defence university: Universidad de La Laguna

Year of defence: 2013

Department:
  1. Psicología Cognitiva, Social y Organizacional

Type: Thesis

Teseo: 353087 DIALNET

Abstract

Representation has been a central issue in cognitive science since the beginning (see Bruner, Goodknow, & Austin, 1956). Nowadays, it is commonly accepted that iconic (or analogical) representation is essential to language comprehension (Barsalou, 1999; Glenberg, Meyer, & Lindem, 1987; Johnson-Laird, 1983; Zwaan & Radvansky, 1998). This means that individuals understand language by representing an analogical structure in their mind that corresponds to the structure of the world being described. However, there are some components of natural language, such as negation, that do not have any analogical correspondence in the real world. Following Wittgenstein¿s classical example (1953), one could well employ an image of a red figure with a superimposed cross to represent the sentence `The figure is not red¿, but one would have still to know that the cross symbolizes negation, and nothing in the image could tell us that. Furthermore, one would have to know what negation itself means. Negation is a syntactic operator that takes an argument (e.g., Spain won the Confederations Cup final in 2013) and reverses its truth value. This means that if an argument is false, then its negation is true (e.g., Spain did not win the 2013 Confederations Cup) and vice versa. This meaning can only be captured symbolically. However, embodiment theory, one of the frameworks that has risen to dominance in cognitive science today, holds that negation is only understood iconically. The main contribution to knowledge of the present thesis is the finding that individuals are able to understand negation symbolically. Although previous studies have shown this using reaction time (Clack & Chase, 1972), we present evidence of the unfolding processing of this kind of representation using the tracking of eye movements. The assumption is that there is a direct relation between what the eyes look at and what the mind processes. Other contributions of the present thesis relate to how the comprehension of negation is modulated by the representation of the negated argument and the context in which it occurs. The meaning of negation is difficult for most individuals to understand, leading to longer processing times and higher error rates compared to the corresponding affirmation. A variety of factors have been proposed to account for this fact, ranging from purely grammatical mechanisms to the influence of affective connotations. But accounts based on semantic and pragmatic factors are surely the most supported by empirical evidence (Miller, 1962; Wason, 1965). Semantic accounts attempt to answer the question of how the meaning of a negative sentence is understood by a representational mind. As a result, they explain the differences between negation and affirmation on the basis of mental processes and representations. A considerable part of this dissertation is dedicated to delving further into these types of cognitive explanations of how negation is understood. First, we make use of a new methodology, the visual world paradigm, to reconcile two well-established cognitive theories: embodiment and mental model theory. Second, we offer a new perspective of the semantic function of negation and examine its impact on the comprehension of concepts that vary in their degree of concreteness. Pragmatic accounts confront the issue of negation complexity from a different perspective. They focus on providing an answer to the questions of why and how people use negation in a communicative context, and consider that comprehension is definitively influenced by how much appropriate (felicitous) information is being used in a given context (Givon, 1978; Wilson & Sperber, 2004). The main pragmatic account (the denial hypothesis) claims that negation is used to deny what a hearer might be mistakenly keeping in mind. In the third part of this dissertation, the role of denial in comprehension is evaluated, again by means of the visual world paradigm methodology. The following is a summary of the different experiments run to study the three main predictions comprising the experimental part of this dissertation. 1. How negation is understood: Evidence from the visual world paradigm. As explained above, the first goal of the present dissertation was to show that individuals are able to understand negation symbolically. To test this, we studied the process of understanding negation and the resulting mental representations. The two-step theory (Kaup, Lüdtke, & Zwaan, 2006), based on the embodiment theory, holds that the understanding of a negative sentence, like the figure was not red, leads to the construction of two iconic mental representations: first, the negated situation (e.g., a red figure) and next, the actual situation (e.g., a green figure). Remarkably, this theory claims that the two representational steps are compulsory, in that they must occur whenever the comprehension of a negative sentence is at stake. In this way, the inclusion of symbolic operations is avoided. Alternatively, the mental model theory, while accepting that individuals will represent the actual situation to understand negation whenever possible, also holds that they can represent the negated situation and apply a symbol for negation. Hence, this theory recognizes two ways of dealing with negation, as well as the possibility of including symbolic operations in its comprehension (Khemlani, Orenes, & Johnson-Laird, 2012). Our hypothesis was that the comprehension of negative sentences is modulated by the availability of the actual situation. In our experiment, this actual situation was made available in what we called the binary context, in which a disjunctive sentence like the figure could be red or green appeared before a negative sentence like the figure was not red. But it was unavailable, in the sense of underspecified (or indefinite), in what we called the multary context, wherein the same negative sentence followed a sentence like the figure could be red, or green, or blue, or yellow. Also, we made use of the visual world paradigm methodology, which allowed us to track semi-continuously participants¿ visual attention over a set of four figures shown in the screen, while they were hearing the passages containing both the context (binary or multary) and the target sentence (affirmative or negative). For the binary context, the same outcome was predicted by both the two-step and the mental model theories: that there would be an initial focus of attention on the figure representing the negated situation (a red figure) followed by a focus on the figure representing the actual situation (a green figure). In contrast, different predictions were anticipated for the multary context: under the mental model theory, the prediction was that there would be persistent attention on the figure representing the negated situation, while the two-step theory predicts a progressive decrease of attention on that figure. In Experiment 1, we confirmed predictions of the mental model theory and found that people shifted their visual attention toward the figure representing the actual situation in the binary context, while focusing exclusively on the negated figure in the multary context. This latter finding, the focus of attention on the negated figure, was confirmed using different tasks in two follow-up experiments (Experiment 2: recognition; Experiment 3: verification) in which negative sentences were presented without any preceding context. The finding of a persistent focus on the negated figure suggests that the comprehension process was relying on the representation of the negated situation, and hence that the actual situation is of no use for understanding negation outside of a binary context. Thus, these findings pose a problem for the two-step theory. They show that the two simulation steps are not necessary to understand negation. Instead, they tend to support the mental model theory, which claims that negation can be understood by keeping the negated situation plus a symbolic tag indicating that this situation is negated. 2. Visual concepts impede negation. The second goal of the present dissertation was to demonstrate that an argument that is symbolic could make negation easier to understand. We predicted that the negation of arguments that involve visual words (related to the representation of an image) would be slower to process than negation involving non-visual words (although visual words are ordinarily easier to process). To test this hypothesis, we carried out two experiments. In Experiment 1, we presented a context that alternated between negation of the argument involving the visual (iconic) word: the boy was brave and he was not asleep and negation of the non-visual (or symbolic) argument: the boy was awake and he was not cowardly. The next sentence (the target) consisted of a similar conjunctive phrase with the same meaning, but with the previously negated word replaced by its contrary visual argument (e.g., the boy was brave and he was awake). The target sentence was similar for both conditions, and we measured the time that people took to read this target. As predicted, results showed that participants took longer to read the target sentence after the negation of the visual argument than after negation of the non-visual argument, although visual concepts had been found to be easier to comprehend than non-visual concepts in a previous lexical decision task. In Experiment 2, we corroborated the previous result using a similar design. In this case, we presented a context that alternated between negation of the argument involving visual word (e.g., the boy was brave and he was not asleep) and negation of the non-visual word. The next sentence (the target) consisted of a similar conjunctive phrase, but without negation (e.g., the boy was brave and he was asleep). This was done to test that the effect found in Experiment 1 was due to the type of representation of the negated word (e.g., asleep), rather than its cancellation. Together, these two experiments lead to the conclusion that iconic representation could impede some symbolic operations such as negation. 3. Inconsistencies make negation plausible: Evidence from the visual world paradigm. The third goal of the present dissertation was to prove whether the context in which the argument is presented could make negation predictable and easier to understand. A special case of this prediction occurs when the negation functions to deny a misconception. Outside of this context, negation is more difficult to understand than affirmation (Givon, 1978). To test this hypothesis, we presented three types of context followed by affirmative or negative sentences (e.g., her dad was (not) poor) while presenting images of the affirmed (e.g., a poor man) or denied entities (e.g., a rich man). In a neutral context (e.g., her dad lived on the other side of town) the participants looked at the affirmed entities before the denied entities. This effect was magnified when the context corresponded to a contextually true belief, that is, when the context and the target sentence were consistent (e.g., She supposed that her dad had enough savings followed by her dad was not poor). However, people looked at the object that corresponded to the negation within the same time frame as they looked at the object that corresponded to the affirmation when the sentence referred to a contextually false belief, that is, when the context and the target sentence were inconsistent (e.g., She supposed that her dad had little savings followed by her dad was not poor). Those results corroborated our prediction. Negation was as easy to comprehend as affirmation when it was used to deny a false belief (or misconception). Outside of this context, negation was more difficult to understand than affirmation. The findings of this section confirmed denial hypothesis predictions, leading to the conclusion that there is an asymmetry in the usage of the main semantic function of negation (truth-value reversal) that modulates comprehension. In particular, they indicate a preference of using negation to reverse the value of mistakenly held ideas. It is likely that this asymmetry in use is related to the important maxim in communication of telling the truth. Conclusions. The empirical analysis addressed in this dissertation has yielded three main findings with important consequences not only for the topic of negation, but also for the more general topic of language comprehension. As a whole, these findings lead us to conclude that the comprehension of negative sentence is modulated by the core semantic meaning of negation (truth-value reversal). This meaning can be only represented symbolically, from whence follows that any representational theory of human language has to consider including symbolic representation for connective concepts like negation. Our results fit better with the mental model theory than with the two-step theory. Also, we have revealed for the first time that iconic (visual) representations slow the comprehension of negative sentences. This finding could be generalized to reasoning and would indicate that symbolic representation could be essential in certain complex tasks. This type of representation allows for ease of operation, because it reduces the processing load on working memory. And finally, we have shown that although negation is more difficult to understand than affirmation, the meaning of negation is easily understood when it is used in a denial context.