Talk: Minerva 2000

A great number of reading studies concern the processes that enable comprehension to occur on-line. Text comprehension requires the coding of structure, as well as the coding of meaning. (slide 2) According to the structural precedence hypothesis, the processing of structure precedes and paves the way for the analysis of meaning. Early in text processing, readers attempt to derive a structural frame for the text. This frame is assumed, to guide the processing of content, and to facilitate its assimilation into a coherent semantic representation. The computation of structure is carried out on-line, on the basis of shallow analysis of the text, taking advantage of structural cues, such as function morphemes and punctuation marks. Once a structural frame has been extracted, attention shifts from structure to meaning. Most of the evidence in support of this hypothesis comes from work on letter detection during silent reading.

In this study, however, we focused on another reading behavior – (slide 3) prosody, that is, the rhythm, intonation, and stress applied when reading aloud. Reading prosody is produced in real time, therefore we believe that the study of reading prosody might shed some light on the real time processes that enable the analysis of text on-line. The experiments I am going to present here examined the proposition that reading prosody is derived on the basis of the syntactic structure of the sentence, and is relatively independent of it’s content.

Experiment 1

According to the structural approach to reading, on-line text processing is guided by early structural analysis. (slide 4) The first experiment examined the hypotheses that reading prosody, produced on-line, is derived on the basis of the structural processing, and that it is relatively independent of semantic analysis. In order to do that we examined how prosodic patterns applied by readers are affected by syntactic and semantic manipulations.

In contrast, (slide 7) when we manipulated syntactic structure by using sentences with completely different structures like these two sentences, (slide 8) the pause patterns applied by readers were clearly differentiated.

However, when structural information is eliminated from these two sentences, by eliminating all function morphemes and using a random word order – like in these strings (slide 9) (read the sentences). Then,
(slide 10) pause patterns become monotonic – the variance of pause duration is much lower they have nearly the same duration, and the differentiation between the two patterns is clearly reduced.

Experiment 2

Some additional support to this conclusion is gained in a second experiment we ran. Assuming, that reading prosody evolves on the basis of structure, we examined if it can be activated through syntactic priming.
(slide 11) In this experiment we used garden path sentences, where structure is temporally ambiguous (read sentence). The prosodic patterns produced by readers in immediate reading of sentences like this are often not fluent, or not coherent. While in non-ambiguous sentences prosody seems to evolve on the basis of structure, it appears that in ambiguous sentences in which the reader cannot figure out the sentence structure on-line, he doesn’t manage to produce the appropriate prosody in real-time. Hence, we hypothesized, that in normal sentences, where structure is processed bottom-up, syntactic priming would not affect reading prosody. However in garden-path sentences where complete structural processing is postponed, syntactic priming might affect the production of reading prosody.

We recorded subjects, reading ambiguous and non-ambiguous sentences, and then asked independent judges to rate their reading prosody. However, before reading each target sentence, subjects read 4 prime sentences. (slide 12) Half of the target sentences were primed by sentences with the same syntactic structure, whereas the other half were primed by sentences consisting of the alternative syntactic interpretation.

(slide 13) As you can see, indeed, syntactic priming had no significant effect on regular, non-ambiguous sentences, however, it yielded significant effect in ambiguous sentences. It seems, then, that reading prosody was affected by the activation of syntactic representation. These results join the results of the previous experiment suggesting, that reading prosody is produced on the basis of structural representation. They also seem to support the idea that a syntactic representation that is independent of semantics is computed at some stage in the process of text analysis.

It might be argued that reading prosody is only produced when reading aloud and that prosody is not inherent to the process of reading itself, and therefore cannot teach us much about text processing. (slide 14) However, 2 lines of research converge in suggesting that this is not the case. First, previous research in speech perception, suggests, that listeners don’t only use the prosodic information provided in the acoustic stream as a key to other linguistic information, but rather prosodic representation is maintained in memory as part of the surface representation of the sentence. Presumably this representation serves as an initial organizing structure in the immediate memory of the sentence, until more abstract and integrative representation is construed.

We asked subjects to read sentences like this one (slide 15). This sentence can be realized with two prosodic versions, however it was always presented in context that favored one of the prosodic versions (slide 16). Later they had an auditory recognition test. Half of the test sentences were new and half were old, and participants were asked to say if they read that sentence in the first phase or not. In the test, half of the old sentences wrealized in a prosodic version that is consistent with that context, while the other half were presented in a different prosodic version, both prosodies were natural. (slide 17) We found that when the auditory presentation in the test is consistent with the prosodic version appropriate to the reading context - recognition rate was higher, and reaction time was faster. Note, that half of the subjects performed the reading phase by reading aloud and the other half performed it in silent reading. Both reading fashions yielded a significant advantage to consistent prosody. This finding seems to support the hypothesis that a prosodic representation is created during reading and maintained in memory. An alternative interpretation, however, is that the prosodic structure applied in the test activates one of the possible syntactic representations, and therefore the consistency advantage that we see is due to the shared syntactic representation and not to the prosodic representation activated in the process of reading. Future experiments are planned to try to disentangle these interpretations.

Conclusion and Preview

(slide 18) Just a few words of conclusion and preview:

(slide 19) We are now going a little further and proposing that reading prosody is not merely an end-product of reading aloud, but rather a prosodic representation is formed during reading (even silent reading) and maintained in memory. The third experiment was the first step in that direction. We’ll further examine the proposition that this prosodic representation is activated by the structural representation of the sentence. Finally, we speculate that a prosodic representation is not just an epiphenomenon, and that it has some functional value – it might serve as an intermediate representation that assists in maintaining the structural frame in working memory while semantic processing is carried out. This hypothesis will be examined in future experiments.