Robin K. Morris

Eye movements and on-line language comprehension processes

Abstract Eye movement records have been used profitably to study on-line comprehension processes in reading. We present some basic facts about eye movements during reading, emphasising issues concerning the use of eye movement data to infer cognitive processes that are involved in (1) word processing, (2) syntactic parsing, and (3) higher-order processes. We review research on each of these topics and present new data dealing with word processing and high-order processes. We conclude that the analysis of eye movement records provides a great deal of useful information about on-line processing and that eye movement recording is a good way to study many critical issues concerning language comprehension processes.

Phonological codes are used in integrating information across saccades in word identification and reading

A major issue in reading is the extent to which phonological information is used in visual word perception. The present experiments demonstrated that phonological information acquired on 1 fixation from a word in the parafovea is used to help identify that word when it is later fixated. A homophone of a target word, when presented as a preview in the parafovea, facilitated processing of the target word seen on the next fixation more than a preview of a word matched with the homophone in visual similarity to the target word. This facilitation was observed both in the time to name an isolated target word and in the fixation time on the target word while silently reading a sentence; the preview was virtually never consciously identified in either task. Because the visual similarity of the preview to the target also plays a part in the facilitative effect on the preview, however, codes other than phonological codes are preserved across saccades.

Eye movement guidance in reading :: the role of parafoveal letter and space information.

The relation between parafoveal letter and space information in eye movement guidance during reading was investigated in 2 experiments. Contingent upon the readers fixation, the type of parafoveal information available to the right of fixation was varied by (a) space information only, (b) space information with letter information added at some delay, or (c) letter and space information simultaneously. In addition, the onset of the relevant parafoveal information was delayed between 0 and 250 ms into the fixation. The time course of processing the 2 types of information (letters or spaces) differed, as did the nature of their impact on the eye movement record. Although both letter and space information influenced saccade length and initial landing positions within words, only letter information had an effect on fixation duration. In addition, fixation duration was affected only by information entering within the first 50 ms of the fixation, whereas saccade length was affected by information arriving at any time during the fixation. The results are consistent with a model of eye movement control in which 2 independent processes are operating in tandem to determine when and where to move the eyes during reading.

The use of thematic role information in parsing: Syntactic processing autonomy revisited

Two eye-movement experiments examined the processing of sentences containing reduced relative constructions. In the first experiment, animacy of the sentential subject, structural ambiguity, and parafoveal preview of syntactically disambiguating material were manipulated. Evidence of disruption was found in temporarily ambiguous sentences, regardless of animacy or preview. In the second experiment, readers with high versus low verbal working memory capacity read the sentences from Experiment 1. High and low-span readers exhibited very similar patterns of processing. As in the first experiment, evidence for disruption was found in temporarily ambiguous sentences whether the sentential subject was animate or inanimate. Sentences with animate subjects were hard to interpret, and relatively late measures of processing indicated that an animate subject made ambiguity especially hard to overcome. We interpret the findings as being consistent with serial, depth-first models of parsing.

Semantic facilitation of lexical access during sentence processing

In three experiments we investigated the effect of a sentence context on naming time for a target word. Contexts were presented by using a rapid serial visual presentation; subjects named the last word of the sentence. In the first two experiments, facilitation was observed for a fully congruent context containing a subject and verb that were weakly related to the target word. No facilitation was observed when either the subject or verb was replaced with a more neutral word. In the third experiment, the fully congruent contexts were modified either to preserve or to disrupt the original relation between the subject and verb. Facilitation was observed in both conditions. The full pattern of results suggests that a combination of lexical items can prime a target word in the absence of priming by any of the lexical items individually. This combination priming is not dependent upon the overall meaning of the sentence.

Eye movement control in reading : evidence against semantic preprocessing

Prior experiments reported by Underwood and his colleagues have suggested that information about the informative parts of parafoveal words that have not yet been fixated can influence where readers fixate next. The basic finding that they have reported is that the eyes move farther into a word when the information that uniquely identifies the word is at the end of the word rather than at the beginning of the word. On the basis of such results, it has been suggested that semantic preprocessing influences eye movement behavior in reading. Some theoretical and methodological problems are raised with the prior experiments and then an attempt to replicate the finding is reported. With a highly accurate eyetracking system, the basic finding could not be replicated. An alternative account of eye movement control in reading is discussed.

Lexical ambiguity and eye fixations in reading : a test of competing models of lexical ambiguity resolution

Abstract Eye movement data were used to test two models of lexical ambiguity resolution. When ambiguous target words are preceded by disambiguating context, the integration model holds that the disambiguating material has no effect on the initial access phase of the meaning assignment process. In contrast, the reordered access model holds that disambiguating material can affect the initial access phase of the process by increasing the availability of one of the potential meanings. Subjects read sentences containing ambiguous words that had one very dominant and another more subordinate meaning. The words were preceded either by (1) evidence that the subordinate meaning of the word should be instantiated, (2) evidence that the dominant meaning should not be instantiated, or (3) neutral material. The ambiguous words were followed by material that conclusively disambiguated them toward their subordinate meanings. Gaze durations on the ambiguous words were longer when the words were preceded by evidence against their dominant meanings. Processing times for the disambiguating material were longer when the words were preceded by neutral material. The results were interpreted as support for the reordered access model.

Eye movements and lexical ambiguity resolution: Effects of prior encounter and discourse topic.

Eye movements were monitored as participants read passages that contained 2 occurrences of a balanced ambiguous word. In Experiment 1, local context was manipulated so that the meaning of the ambiguous word either remained the same or changed from the 1st to 2nd encounter. In Experiments 2 and 3. global context was manipulated by shifting the discourse topic between the 2 instances of the ambiguous word. Gaze durations on the 2nd instance of the ambiguous word were shorter when the meaning remained consistent than when the meaning changed, and this facilitation was impervious to changes in the discourse structure. In contrast, processing time in the region immediately following the target was longer when the word meaning changed, but only when the topic of the discourse remained the same throughout the passage. When the topic was shifted, this effect disappeared.

Focus as a contextual priming mechanism in reading

In two experiments, we found that readers are sensitive to manipulations of syntactically marked focus and that focus is an effective message level contextual priming mechanism. Changes in focus resulted in changes in sentence context effects on subsequent target word processing. This was demonstrated in latency to name the target word (Experiment 1) and in initial looking time on the target in silent reading (Experiment 2). Experiment 2 also revealed direct effects on the focused items, as readers made fewer regressions and spent less total time on a word that was focused than when it was not focused. However, no initial processing time effects were found on the focused word.

Effects of syntactic category assignment on lexical ambiguity resolution in reading: an eye movement analysis.

Readers’ eye movements were monitored as they read sentences containing lexically ambiguous words whose meanings share a single syntactic category (e.g.,calf), lexically ambiguous words whose meanings belong to different syntactic categories (e.g.,duck), or unambiguous control words. Information provided prior to the target always unambiguously specified the context-appropriate syntactic-category assignment for the target. Fixation times were longer on ambiguous words whose meanings share a single syntactic category than on controls, both when prior context was semantically consistent with the subordinate interpretation of a biased ambiguous word (Experiment 1) and when prior context was semantically neutral as to the intended interpretation of a balanced ambiguous word (Experiment 2). These ambiguity effects, which resulted from differences in difficulty with meaning resolution, were not found when the ambiguity crossed syntactic categories. These data indicate that, in the absence of syntactic ambiguity, syntactic-category information mediates the semantic-resolution process.