Article Figures & Data
Figures
- Figure 1.
ERP responses on a frontal (Fz) and a parietal (Pz) exemplar electrode (upper left and right panels, respectively). Blue shades indicate the N400 (300–500 ms) and the N700 (700–1000 ms), the green shade the N400 time window. Negative is plotted upwards. Lower panels show bar charts of amplitudes averaged within the predifined time windows and over electrodes in the frontal and parietal Regions-of-Interest, which are shown in the middle. Error bars indicate 95% confidence intervals (**p < 0.01, ***p < 0.001). Metaphors evoked an enhanced frontal negativity relative to Literals both in the N400 (300–500 ms) and the N700 (700–1000 ms) time windows during right visual field / left hemisphere (LH) presentation. This effect was the more enhanced the more abstract the metaphors were, and it is unique and specific to the processing of metaphorical senses of concrete words (“sweet”); no such effect has been reported before for novel metaphors or non-sentential stimuli. Literals evoked a greater frontal negativity in the N700 time window during right hemisphere (RH) relative to LH presentation, which corresponds to a typical concreteness effect. Both metaphorical and literal novel word pairs evoked a greater parietal negativity in the N400 time window during LH compared with RH presentation: contrary to some prominent language lateralization models, novel expressions engaged the LH more than the RH. Grand-average ERP plots over all electrode sites for LH and RH presentation are provided in Extended Data Figures 1-1, 1-2, respectively. Electrophysiological evidence of successful lateralized presentation of target words is presented in Extended Data Figure 1-3.
- Figure 2.
Topographical difference maps (metaphor–literal) of ERP responses in the N400 and N700 time windows for each hemifield presentation. Blue colors indicate greater negativities for metaphors, relative to literals, which is apparent in both time windows over frontal areas during LH presentation. Extended Data Figure 2-1 shows topographical maps of the frontal effects in the side contrast (RH–LH) and demonstrates a typical concreteness for literal expressions in the N700 time window. Extended Data Figures 2-2, 2-3 show effects evoked at the prime word (noun).
- Figure 3.
Abstractness effect evoked by metaphors over the frontal ROI. Upper panel shows ERP responses for individual trials to low-concreteness metaphors and high-concreteness literals. Electrophysiological responses over frontal electrode sites were the more negative, the less concrete (i.e., more abstract) the metaphors were both in in the 300- to 500-ms time window during RH presentation and also in the 700- to 1000-ms time window bilaterally. Lower panel shows bar charts of the median split high-concreteness and low-concreteness metaphors relative to median split high-concreteness literals. Stars in brackets (*) indicate effects that were significant if concreteness was not included in the models (i.e., concreteness accounted for these effects). Error bars indicate 95% confidence intervals (*p < 0.05, **p < 0.01).
Tables
Metaphors mean (SD) Literals mean (SD) Levene’s F value t value/ S value 95% confidence interval Bigram frequency 3.81 (4.36) 4.06 (4.29) 0.293 0.652 [–0.496, 0.986] Meaningfulness 4.04 (0.92) 5.39 (0.95) 0.009 15.8*** [1.18, 1.51] Literalness 3.37 (0.75) 5.11 (0.86) 3.92* 200*** [1.40, 1.85] Concreteness 2.80 (0.68) 4.49 (0.92) 21.7*** 200*** [1.44, 1.81] Imageability 4.06 (0.66) 5.28 (0.67) 0.018 19.5*** [1.09, 1.34] Valence (±3) –0.84 (1.15) –0.66 (1.27) 3.63 2.53* [0.038, 0.309] Arousal 3.81 (0.83) 3.71 (0.88) 0.550 –1.87 [–0.202, 0.005] Noun concreteness 2.49 (0.72) 4.29 (0.73) 3.89* 191*** [1.57, 1.92] When the variance of a measure was not equal between metaphors and literals, as reported by a median centered Levene’s test (F value), a sign test (S value) was used, otherwise a t test (t value). Metaphorical and literal expressions differed on all properties except for their bigram frequency and arousal value. The full stimulus list is shown in Extended Data Table 1-1.
↵* p < 0.05.
↵*** p < 0.001.
Concrete Abstract tracteur bavard talkative tractor demande brisée broken request narration mielleuse honeyed narrative affirmation biscornue quirky statement agenda maigre lean agenda imprudence vide empty recklessness Metaphor amende piquante zesty fine règlement tricoté knitted settlement rumeur bouillante boiling rumor oubli dense dense oblivion pensée enfumée smoky thought phrase graisseuse fat sentence branche dansante dancing branch concept tuméfié swollen concept figue croquante crunchy fig batelet usé used dinghy chouquette délicieuse delicious owl soldat maigriot skinny soldier mamie hurlante screaming granny catacombe fermée closed catacomb Literal nectarine piquante zesty nectarine glaive décorée decorated sword sucrerie pimentée spicy candy conserve empilée stacked can marmelade coulante flowing marmalade artiste rassasiée satiated artist lasagne bouillante boiling lasagna colloque vide empty conference Both conditions were split along their respective median concreteness values. Since less concrete literal expressions are not truly abstract and do not constitute a theoretically sound category, the best exemplars of the concrete literal condition, high concreteness literals served as baseline for comparison with both high-concreteness and low-concreteness (i.e., abstract) metaphors.
Extended Data Table 1-1
Complete stimulus list. Every adjective was paired with two nouns to form both a metaphorical and a literal expression. Each participant saw either the literal or the figurative pairing for one particular adjective. Download Table 1-1, DOC file.
Extended Data Figure 1-1
Grand-average ERP plots for LH presentation over each electrode site. Negative is plotted upwards, frontal sites are above, parietal sites are below. Black line is the literal, red line is the metaphorical condition. A frontal negativity is apparent between 300–500 ms and 700–1000 ms as well. Download Figure 1-1, TIF file.
Extended Data Figure 1-2
Grand-average ERP plots for RH presentation over each electrode site. Negative is plotted upwards, frontal sites are above, parietal sites are below. Black line is the literal, red line is the metaphorical condition. No difference is apparent frontally between 300–500 or 700–1000 ms either. Download Figure 1-2, TIF file.
Extended Data Figure 1-3
Markers of lateralized processing. Topographical maps in the upper row show the difference of RH–LH presentation: cold colors indicate greater negativities for RH (left visual field), warm colors for LH (right visual field) presentation. Upper left represents the N1 for literal word pairs, and upper right the selection negativity (SN) for metaphors. Lower row ERP waveforms show responses on a left and a right exemplar electrode. Red shades indicate the 100- to 200 ms (N1) time window, blue shades the 300- to 1000-ms (SN) time window. Negative is plotted upwards. Download Figure 1-3, TIF file.
Extended Data Figure 2-1
Topographical maps of the frontal effects in the side contrast (RH–LH). Cold colors indicate greater negativities for RH (left visual field) presentation, warm colors for LH (right visual field) presentation. In the 300- to 500-ms time window neither metaphors (p = 0.11) nor literals (p = 0.13) were processed differently during lateralized presentation. In the N700 time window, literals evoked a greater negativity in the right than in the LH (β = –0.17, SE = 0.06, F (1,2913) = 8.63, p = 0.003), while metaphors evoked the same amount of brain electricity in both hemispheres (p = 0.059; Bonferroni corrected α-level = 0.0125). Download Figure 2-1, TIF file.
Extended Data Figure 2-2
Grand-average topo plots of ERPs at the prime word (noun) at each electrode site. Nouns were presented centrally for 200 ms followed by a blank screen jittered between 300 and 400 ms. Onset of visual word presentation is at 0, it is preceded by a 200-ms baseline and followed by 500-ms analysis window. Download Figure 2-2, TIF file.
Extended Data Figure 2-3
Upper row shows ERP responses at two exemplar electrodes (Fz and Pz), lower row shows a topo map of ERPs in the N400 time window (300–500 ms) to the prime word (noun). Nouns evoked a typical N400 response, confirmed by a paired t test on participant averaged data over the parietal ROI (Mdiff = 0.39 μV, SDdiff = 0.41 μV), t (37) = 5.82, p < 0.001, 95% CI [0.25, 0.53 μV], Hedges’ g av = 0.43. Such an effect could be due to a variety of psycholinguistic variables (e.g., frequency, length, neighborhood size, etc.), since prime nouns were allowed to vary on properties, but target adjectives were fully controlled. Expressions in the literal and metaphorical conditions ended on the same adjectives, thus each participant saw the same set of target words. The response at the noun is not likely to have influenced outcomes at the adjective. If it influenced the baseline for adjectives, then responses to literals should have been artefactually reduced, which should have yielded an enhanced N400 response to metaphors (which was not the case). Download Figure 2-3, TIF file.
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