"A fighter is a lion". Neuropsychological indexes in comprehending frozen metaphors

This paper considers the cognitive and linguistic processes underlying the comprehension of frozen metaphors, by analyzing both neuropsychological and behavioral data. In order to explore the dichotomy between the pragmatic models (i.e. the metaphor as a semantic anomaly) and the direct comprehension view (the metaphor as a “standard” meaning) on the one hand, and between an iconic (more imagery-based) vs. not iconic (linguistic) representational modality on the other hand, the paper analyzed the event-related potentials (ERPs) and the behavioral data (response time) of subjects submitted to verbal stimuli. 36 participants were required to comprehend metaphoric and literal sentences, half congruous (semantically not anomalous) and half uncongruous (semantically anomalous). The morphological analysis of the electroencephalographic (EEG) profile allowed to observe two negative deflections (the N3–N4 complex), differently distributed on the scalp surface. Repeated measures analysis of variance (ANOVA) applied to peak amplitude and latency variables underlined the different role of these deflections in metaphoric decoding. That is, the N4 effect appears to detect the presence of a semantic anomaly of the utterance (uncongruous condition) more localized on the posterior (Pz) area, but not sensitive to the metaphoric/literal content of the stimulus. On the contrary, N3 effect shows an ampler negativity for the metaphoric decoding, increased on the occipital area, likely a marker of a specific iconic representational format. Thus, though not equivalent, the two comprehension processes are not differentiated as a function of the way of the meaning access (direct or indirect), nor for their cognitive complexity (no response time variation) but for the typology of the representational format, more imagery-based for metaphoric stimuli, as it was showed by an increased N3 on the occipital visual area.