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. 2018 Dec 21;7:e39061. doi: 10.7554/eLife.39061

Figure 2. Results of the Spatial Representational Similarity Analysis.

(A) The time series of spatial similarity R values combined across the within-pair and between-pair correlations. The horizontal line indicates a threshold of R = 0.04 where the general increase in spatial correlation was largest. (B) The time series of spatial similarity R values for pairs in which the same word was predicted (within-pairs, shown in red) and in which a different word was predicted (between-pairs, shown in blue). Both the within- and the between-pair spatial similarity time series showed a sharp increase at ~100 ms and a decrease at ~500 ms after the onset of each word. Between −880 and −485 ms before the onset of the final word, the spatial similarity was greater when the same word was predicted than when different words were predicted (within-pairs >between-pairs: t(25) = 3.751, p < 0.001). (C) Scatter plots of spatial similarity values averaged between −880 and −485 ms before the onset of the final word in 26 participants. In most participants (18/26) the within-pair spatial correlations were greater than the between-pair spatial correlations. (D) Cross-temporal spatial similarity matrices for the within- and between-pair correlations (Red: positive correlations; blue: negative correlations). Left and middle: Both sets of pairs showed increased spatial similarity along the diagonal with greater similarities for the within- than the between-pairs in the −900 – −500 ms interval prior to the onset of the final word. Right: The matrix shows the cluster with a statistically significant difference between the within-pair and between-pair spatial correlations (p = 0.002, cluster-randomization approach controlling for multiple comparisons over time). The absence of ‘off-diagonal’ correlations suggests that the spatial pattern of neural activity associated with the predicted word was reliable but changed over time.

Figure 2—source data 1. Data used for plotting Figure 2 as well as its supplementary Figures.
elife-39061-fig2-data1.zip (42.4MB, zip)
DOI: 10.7554/eLife.39061.009

Figure 2.

Figure 2—figure supplement 1. Results of the Spatial Representational Similarity Analysis after matching the number of pairs between the within-pair and between-pair correlations.

Figure 2—figure supplement 1.

(A) The time series of spatial similarity R values for the pairs in which the same word was predicted (within-pair, shown in red) and in which a different word was predicted (between-pair, shown in blue). Within the −880 – −485 ms interval relative to the onset of the final word, the spatial similarity was greater when the same word was predicted than when different words were predicted (−880 – −485 ms before its onset; t(25) = 2.393, p = 0.025). (B) Scatter plots of the spatial similarity values averaged between −880 and −485 ms before the onset of final word in 26 participants. In most participants (17/26) the within-pair spatial correlations were greater than the between-pair spatial correlations.
Figure 2—figure supplement 2. Results of the Spatial Representational Similarity Analysis in a subset of sentence pairs that had the same pre-sentence-final word (SFW-1) but predicted a different SFW (a subset of between-pairs, shown in blue), and a subset of sentences that constrained for these same SFWs, but which differed in the SFW-1 (a subset of within-pairs, shown in red).

Figure 2—figure supplement 2.

The spatial patterns produced by the sentence pairs that predicted the same SFW (i.e. within-pairs) appeared to be more similar than the sentence pairs that predicted different SFW (i.e. between-pairs), even though the between-pairs contained the same SFW-1 (t(25) = 1.81, p = 0.08). This strongly suggests that the observed effect reflects the prediction of the SFW rather than the lexical processing of the SFW-1.
Figure 2—figure supplement 3. Results of the Spatial Representational Similarity Analysis for two subsets of trials where (A) sentences ending with expected words were seen first or (B) sentences ending with unexpected words were seen first.

Figure 2—figure supplement 3.

The time series of spatial similarity R values for the pairs in which the same word was predicted (within-pair) are shown in red, while the time series for the pairs in which a different word was predicted (between-pair) are shown in blue. The spatial similarity was greater when the same word was predicted than when different words were predicted in both subsets. No significant difference was found between the two subsets of trials, as indicated by the lack of a main effect of Order (Expected First, Unexpected First) (F(1,25) = 0.747, p = 0.396, η2 = 0.029) or an interaction between Order (Expected First, Unexpected First) and Pairs (Within-pair, Between-pair) (F(1,25) = 1.804, p = 0.191, η2 = 0.067).
Figure 2—figure supplement 4. Results of the Spatial Representational Similarity Analysis for pairs in which the same word was predicted (within-pair, shown in red) and in which the same syntactic category (e.g. nouns or verbs) of words (but not the same words) was predicted (within-category, shown in cyan).

Figure 2—figure supplement 4.

The spatial similarity was greater when the same word was predicted than when different words belonging to the same syntactic category were predicted: t(25) = 3.559, p = 0.002. This suggests that the high within-pair spatial similarity relates to the specific representation of the predicted words over and above the syntactic category that the predicated words belong to.