Idiom and metaphor comprehension in schizophrenia

Anna Cieślicka, Karolina Rataj (Adam Mickiewicz University, Poznań) Edward Gorzelańczyk, Marta Kuklińska (Kazimierz Wielki University, Bydgoszcz)

Research conducted into the processing of language by individuals with schizophrenia has repeatedly demonstrated that such patients experience difficulty comprehending nonliteral forms of discourse such as metaphors, idiomatic expressions, proverbs or irony (see, for example, Chapman, 1960; De Bonis et al., 1997; Brûne i Bodenstein, 2005). Many current models of figurative language processing emphasize the role of the suppression mechanism (Gernsbacher and Robertson 1999), which is necessary in suppressing the contextually inappropriate literal meaning and constructing the figurative interpretation of a metaphorical utterance (see, for example, the graded salience hypothesis put forward by Giora 1997, 1999, 2003).

With regard to patients suffering from aphasia, who, like schizophrenics, frequently fail to comprehend nonliteral language, Papagno, Tabossi, Colombo and Zampetti (2004) have suggested that the major cause of this failure might be a dysfunction of the language suppression mechanism in such patients. If the mechanism of suppression does not aid the language processing system in inhibiting the irrelevant literal meaning, comprehending figurative language becomes a difficult task, especially when discourse lacks pragmatic cues which might suggest a figurative reading of the idiomatic phrase. Some of such cues suggesting the necessity to reject the literal meaning of the idiomatic phase might be their ill-formedness, opaqueness, or nonliteralness, where ill-formedness refers to idioms being ungrammatical, opaqueness indicates inability to infer the figurative meaning of the whole idiom from the literal analysis of its components, whereas nonliteralness refers to those idioms which cannot be understood in a literal fashion. Under this proposal, while processing ill-formed, opaque and nonliteral idioms, the language comprehension system quickly rejects an incorrect literal interpretation and retrieves the idiom's figurative meaning, thanks to the pragmatic cues boosting the suppression mechanism. On the other hand, when faced with grammatically and lexically well-formed idioms, with a logical and coherent literal interpretation and transparent meaning, aphasic patients, lacking the necessary discourse cues, fail to suppress the inappropriate literal sense and experience difficulty in constructing the metaphorical interpretation.

The aim of the study described in this paper is verifying this proposal with regard to the processing of idioms by schizophrenic patients, as well as investigating how schizophrenic patients process metaphors differing in terms of their difficulty. The study consists of two experiments, each of which has been conducted with a different group of schizophrenics.

Experiment 1 aimed at investigating the degree to which such dimensions of idioms as well-formedness, literalness, and transparency influence the ease of their comprehension by schizophrenic patients. Twenty Polish idiomatic expressions, varying in terms of their literalness, transparency and well-formedness, were used in the experiment, which employed the lexical decision priming paradigm. Following the display of the idiom embedded in figurative-biasing context, each participant was presented with one of the three target types: a word related to the figurative meaning of the whole idiomatic phrase, a word related to the literal meaning of the last word of the idiom, and an unrelated control. Participants' task was to read each sentence carefully and make a lexical decision about the following visual target.

In Experiment 2, the priming sentences included metaphors differing in terms of their difficulty. As in Experiment 1, participants made lexical decisions about targets which were related literally or figuratively to the metaphors, or which were unrelated.

Differences in reaction times obtained for the various target types were used for estimating the activation of literal or figurative meanings in the course of processing idioms and metaphors by schizophrenic patients. The obtained results are interpreted in light of the potential role of various dimensions of idiom and metaphor variability in enhancing the activity of the suppression mechanism and facilitating figurative language processing in schizophrenia.