Suiping Wang

Semantic and Plausibility Effects on Preview Benefit during Eye Fixations in Chinese Reading.

The boundary paradigm (Rayner, 1975) was used to examine whether high level information affects preview benefit during Chinese reading. In two experiments, readers read sentences with a 1-character target word while their eye movements were monitored. In Experiment 1, the semantic relatedness between the target word and the preview word was manipulated so that there were semantically related and unrelated preview words, both of which were not plausible in the sentence context. No significant differences between these two preview conditions were found, indicating no effect of semantic preview. In Experiment 2, we further examined semantic preview effects with plausible preview words. There were four types of previews: identical, related & plausible, unrelated & plausible, and unrelated & implausible. The results revealed a significant effect of plausibility as single fixation and gaze duration on the target region were shorter in the two plausible conditions than in the implausible condition. Moreover, there was some evidence for a semantic preview benefit as single fixation duration on the target region was shorter in the related & plausible condition than the unrelated & plausible condition. Implications of these results for processing of high level information during Chinese reading are discussed.

Involvement of left inferior frontal gyrus in sentence-level semantic integration

Using event-related functional MRI, we examined the involvement of the left inferior frontal gyrus (LIFG) in semantic integration in reading Chinese sentences. During scanning, Chinese readers read individually presented sentences and judged whether or not a sentence was semantically acceptable. Behaviorally, those sentences with a small degree of semantic violation were found to be more difficult to reject relative to sentences with a large degree of semantic violation, indicating that more semantic integration occurred in the former than in the latter condition. Direct contrast revealed significantly greater brain activity in the LIFG for sentences with a small violation, relative to those with a large violation, but no differences in any anterior temporal cortical areas between the two types of anomalous sentences. The results are in line with the idea that the LIFG plays a critical role in integrating individual word meanings to coherent sentence-level messages, but not with the idea that semantic integration depends on anterior temporal cortex in language comprehension.

Do Chinese readers obtain preview benefit from word n + 2? Evidence from eye movements.

The boundary paradigm (K. Rayner, 1975) was used to determine the extent to which Chinese readers obtain information from the right of fixation during reading. As characters are the basic visual unit in written Chinese, they were used as targets in Experiment 1 to examine whether readers obtain preview information from character n + 1 and character n + 2. The results from Experiment 1 suggest they do. In Experiment 2, 2-character target words were used to determine whether readers obtain preview information from word n + 2 as well as word n + 1. Robust preview effects were obtained for word n + 1. There was also evidence from gaze duration (but not first fixation duration), suggesting preview effects for word n + 2. Moreover, there was evidence for parafoveal-on-foveal effects in Chinese reading in both experiments. Implications of these results for models of eye movement control are discussed.

The anterior left inferior frontal gyrus contributes to semantic unification

Semantic unification, the process by which small blocks of semantic information are combined into a coherent utterance, has been studied with various types of tasks. However, whether the brain activations reported in these studies are attributed to semantic unification per se or to other task-induced concomitant processes still remains unclear. The neural basis for semantic unification in sentence comprehension was examined using event-related potentials (ERP) and functional Magnetic Resonance Imaging (fMRI). The semantic unification load was manipulated by varying the goodness of fit between a critical word and its preceding context (in high cloze, low cloze and violation sentences). The sentences were presented in a serial visual presentation mode. The participants were asked to perform one of three tasks: semantic congruency judgment (SEM), silent reading for comprehension (READ), or font size judgment (FONT), in separate sessions. The ERP results showed a similar N400 amplitude modulation by the semantic unification load across all of the three tasks. The brain activations associated with the semantic unification load were found in the anterior left inferior frontal gyrus (aLIFG) in the FONT task and in a widespread set of regions in the other two tasks. These results suggest that the aLIFG activation reflects a semantic unification, which is different from other brain activations that may reflect task-specific strategic processing.

Broca's area plays a role in syntactic processing during Chinese reading comprehension

Event-related functional magnetic resonance imaging (ER-fMRI) was adopted to examine brain activation of syntactic processing in reading logographic Chinese. While fMRI data were obtained, 15 readers of Chinese read individually presented sentences and performed semantic congruency judgments on three kinds of sentences: Congruous sentences (CON), sentences with a semantic violation (SEM), and sentences with both semantic and syntactic violations (SEM+SYN). The two types of incongruous sentences were matched in the degree of semantic plausibility. Three brain regions were identified showing significantly different levels of percent signal change across the three conditions, including BA44 in the left inferior frontal gyrus (IFG) and both BA9 and BA10/46 in the left middle frontal gyrus (MFG). Furthermore, the mean percent signal change in the left BA44 observed in the SEM+SYN condition was significantly stronger than that in either the SEM or the CON condition, while the latter two conditions were at a similar level, implying an important role of this area in Chinese syntactic processing. These results, in conjunction with those found in alphabetic scripts, suggest that there are some common neural substrates underlie syntactic processing across distinctive writing systems such as the logographic Chinese and the alphabetic English.

The role of left inferior frontal gyrus in explicit and implicit semantic processing

Using event-related functional MRI, we examined the involvement of the left inferior frontal gyrus (LIFG) in explicit and implicit semantic processing of Chinese sentences. During scanning, Chinese readers read individually presented normal sentences with a contextually expected or unexpected target noun and were asked to perform an explicit or implicit semantic task (semantic or syntactic violation judgment). The conjunction analysis of the two tasks revealed LIFG as the critical brain region for semantic integration. Further, a cross-task comparison showed more extensive activations for the expectancy effect in the explicit task than in the implicit task in regions including bilateral anterior cingulate cortex/dorsolateral prefrontal cortex, left middle temporal gyrus, and right inferior frontal gyrus. These results indicate that LIFG is responsible for the integration process per se and that other brain regions observed in previous studies using explicit semantic tasks may be due to task-induced generic processes (e.g., cognitive control).

Guidance of visual attention from working memory contents depends on stimulus attributes.

Recent work shows that items maintained in working memory could guide the orienting of attention in visual search, demonstrating an interesting interaction between working memory and attention. For such guidance effect, some studies emphasize the importance of search task type: for fixed-target search, task-irrelevant memory items stay inside the attentional focus and guides attention; for varied-target search, these items stay outside attentional focus and do not guide attention. With two experiments, we showed that stimulus attribute of items held in working memory can play an important role in attentional guidance. The first behavioral experiment duplicated a previous fixed-target search paradigm demonstrating robust guidance effect but failed to find such effect when the stimuli was simply changed from colored shapes to complex artificial shapes. The second event-related potential experiment duplicated a previous varied-target search paradigm that used complex shapes but did not observe any guidance effect. A clear guidance effect was found when we changed the stimuli to colored shapes. The results suggest that attentional guidance from working memory depends on stimulus attributes of the items held in working memory. When effective attribute is used, task-irrelevant items that stay outside the attentional focus are still able to guide attention.

Processing of compound-word characters in reading Chinese: An eye-movement-contingent display change study

Readers’ eye movements were monitored as they read Chinese two-constituent compound words in sentence contexts. The first compound-word constituent was either an infrequent character with a highly predictable second constituent or a frequent character with an unpredictable second constituent. The parafoveal preview of the second constituent was manipulated, with four preview conditions: identical to the correct form; a semantically related character to the second constituent; a semantically unrelated character to the second constituent; and a pseudocharacter. An invisible boundary was set between the two constituents; when the eyes moved across the boundary, the previewed character was changed to its intended form. The main findings were that preview effects occurred for the second constituent of the compound word. Providing an incorrect preview of the second constituent affected fixations on the first constituent, but only when the second constituent was predictable from the first. The frequency of the initial character of the compound constrained the identity of the second character, and this in turn modulated the extent to which the semantic characteristics of the preview influenced processing of the second constituent and the compound word as a whole. The results are considered in relation to current accounts of Chinese compound-word recognition and the constraint hypothesis of Hyönä, Bertram, and Pollatsek (2004). We conclude that word identification in Chinese is flexible, and parafoveal processing of upcoming characters is influenced both by the characteristics of the fixated character and by its relationship with the characters in the parafovea.

The role of the left prefrontal cortex in sentence-level semantic integration

Whether left inferior frontal gyrus (LIFG) activation during sentence comprehension reflects semantic integration or domain-general cognitive control remains unclear. To address this issue, 26 participants were presented with sentences word by word during fMRI scanning and were asked to perform two semantic tasks, one explicit (semantic congruency judgment) and one implicit (font size judgment). In the two language tasks, semantic integration load was parametrically manipulated with high cloze, low cloze and semantically violated sentences. Participants also performed a classical Stroop task during scanning. Conjunction analysis of the explicit and implicit tasks revealed two regions in left inferior frontal gyrus associated with semantic integration load: one anterior region (aIFG) and one posterior region (pIFG). However, only the pIFG region was also activated during the Stroop task. These results indicate that different regions in the LIFG play different roles in semantic integration, with aIFG more important for domain-specific processing and pIFG more important for domain-general cognitive control.

The time course of semantic and syntactic processing in Chinese sentence comprehension: Evidence from eye movements

In the present study, we examined the time course of semantic and syntactic processing when Chinese is read. Readers’ eye movements were monitored, and the relation between a single-character critical word and the sentence context was manipulated such that three kinds of sentences were developed: (1) congruent, (2) those with a semantic violation, and (3) those with both a semantic and a syntactic violation. The eye movement data showed that the first-pass reading times were significantly longer for the target region in the two violation conditions than in the congruent condition. Moreover, the semantic + syntactic violation caused more severe disruption than did the pure semantic violation, as reflected by longer first-pass reading times for the target region and by longer go-past times for the target region and posttarget region in the former than in the latter condition. These results suggest that the effects of, at least, a semantic violation can be detected immediately by Chinese readers and that the processing of syntactic and semantic information is distinct in both first-pass and second-pass reading.