Processing figurative language -

EEG-study with coherence analysis

Carla Berghoff¹, Sabine Weiss², Horst M. Müller¹

1) Experimental Neurolinguistics Group – SFB 360, University of Bielefeld, Germany

2) Center for Brain Research , Cognitive Neuroscience Group, Medical University of Vienna, Austria

We investigated the reception of German spoken language using the analysis of EEG coherence. The study focusses on processing different types of sentences such as literal and figurative ones.

literal: Sie hilft dem Schauspieler auf die Bühne.
(She helps the actor onto the stage.)

figurative unambiguous: Sie hilft dem Schauspieler auf die Sprünge.
(She gives the actor a helping hand.)

figurative ambiguous: Er tritt ihr auf die Füße. (He steps on her toes.)

Linguistic theories assume different models for processing figurative compared to literal language: e.g. the standard pragmatic model assumes literal priority in understanding figurative language whereas other models suggest e.g. a parallel processing of both meanings, a direct access to the figurative meaning without literal analysis or access dependent on a keyword in a figurative sentence [1].

Neuropsychological [2] as well as neurophysiological studies [3] support the assumption of differences in processing figurative compared to literal language. Specific brain damage reduces the ability of understanding figurative language [2]. It is shown with brain mapping techniques that processing of figurative language involves parts of the right hemisphere in addition to the language areas in the left hemisphere [3]. Nevertheless, the importance of both the left and the right hemisphere for processing figurative language is still not clear. Moreover, the time course of its processing is scarcely investigated.

In the study were recorded EEGs from 29 subjects (German, 14 m, Ø=23.4 ± 3.6 y) listening to 244 sentences (included 24 unambiguous and 24 ambiguous idioms). For data analysis, spectral coherence was calculated [4]. This method allows the investigation of the degree of functional cooperation between neuronal substrates underlying the generation of the signals.

Significant results were found in the beta1-frequency band (12-18 Hz). This coincides with findings from previous studies showing that the beta1-band is associated with specific linguistic processes during sentence comprehension [5]. The results clearly support the assumption of differences in neuronal processing of figurative and literal sentences. They show that unambiguous idioms compared to literal sentences elicit synchronization within the left and the right hemisphere. The strongest differences are found for the interhemispheric coherences. We found strikingly higher synchronization between the hemispheres for idiomatic compared to literal sentences and this strong difference only appears from the moment on the figurative meaning is retrieved. Ambiguous sentences compared to literal ones did not evoke any difference in processing. That leads to the assumption that ambiguous sentences are processed rather like literal sentences.

In summary, the results show that neuronal processes only differ from the moment on the figurative meaning is retrieved and for unambiguous idiomatic expressions neither the left nor the right hemisphere alone but a cooperation between the hemispheres plays the most important role.

[1] Glucksberg, S. (2001) (ed.). Chapter 5 in: Understanding figurative language. From Metaphors to Idioms. Oxford: University Press.

[2] Papagno, C. & Tabossi, P. (2002). Brain and Language, 83:78-81.

[3] Bottini, G. et al. (1994). Brain, 117:1241-1253.

[4] Weiss, S. & Müller, H.M. (2003). Brain and Language 85: 325-343.

[5] Weiss, S. et al. (2005). International Journal of Psychophysiology (in press).