Search PubMed⌕ Search

Biomedical subjects

R K Morris

Publications and source records attributed to R K Morris.

14 recordsLinked to original sources
PubMed2001

Learning new word meanings from context: a study of eye movements.

This study examined how readers establish the meaning of a new word from the sentence context during silent reading. Readers' eye movements were monitored while they read pairs of sentences containing a target word, context, and a word related to the target word. The target word varied in familiarity (high, low, or novel). The context varied in informativeness about the meaning of the target word (informative or neutral). The amount of time readers spent on the context depended on both the familiarity of the target word and the informativeness of the context. Readers spent additional time on the related word only when the context was neutral and the target was novel. These results indicate that readers were able to determine which areas of text were relevant and used the information to infer a meaning for the novel word.

Adult↗
PubMed2000

Priming in sentence processing: intralexical spreading activation, schemas, and situation models.

A series of eye-tracking experiments investigated priming in natural language understanding. Intralexical spreading activation accounts of priming predict that the response to a target word will be speeded (i.e., primed) when strong associates appear prior to the target. Schema-based priming accounts predict that priming will occur when the target word is a component of an activated schema or script. Situation model accounts predict that priming will occur when a target word can be integrated easily into an evolving discourse representation. In separate experiments, we measured the effect of associated words, synonyms, and identity primes on processing times for subsequently encountered target words. Our designs crossed prime type (e.g., synonyms vs. unassociated words) with semantic plausibility (i.e., the target word was a plausible vs. an implausible continuation of the sentence). The results showed that identity primes, but not associates or synonyms, primed target words in early measures of processing like first fixation and gaze duration. Plausibility effects tended to emerge in later measures of processing (e.g., on total reading time), although some evidence was obtained for early effects of semantic plausibility. We propose that priming in naturalistic conditions is not caused by intralexical spreading activation or access to precompiled schemas.

Eye Movements↗
PubMed2000

Stress grouping improves performance on an immediate serial list recall task.

Five experiments investigated whether perceptual patterning afforded by imposing a recurrent stress pattern on auditorially presented lists has a positive effect on list recall. The experiments also addressed whether the recall advantage reflected the salience that the stress pattern created for certain items or whether the recall advantage arose from the distinct grouping configurations that were produced by the stress pattern. The authors explored these issues by examining immediate serial-recall performance for spoken lists that either did or did not have a stress pattern imposed on them. Lists had an anapest or dactylic stress pattern or were monotone and consisted of two stimulus types, either digit names or common English nouns. Results showed that stress patterns enhanced serial-recall performance and that the recall benefit derived primarily from the perceptual grouping afforded by the stress patterns. Results also showed that the grouping benefit derived from stress patterning generalizes to monotone lists. In contrast, salience effects are attached to the stimulus per se and do not transfer.

Adult↗
PubMed2000

Lexical processing and text integration of function and content words: evidence from priming and eye fixations.

The results of two experiments comparing processing of function words and content words are reported. In Experiment 1, priming was present for both related function and related content word pairs, as measured in lexical decision response times. In Experiment 2, participants' eye movements were monitored as they read sentences containing either a high- or a low-frequency function or content target word. Average word length and word frequency were matched across the function and content word conditions. Function words showed frequency effects in first-fixation and gaze duration that were similar to those seen for content words. Clear differences in on-line processing of function and content words emerged in later processing measures. These differences were reflected in reading patterns and reading time measures. There was inflated processing time in the phrase immediately following a low-frequency function word, and participants made more regressions to the target word in this condition than in the other three conditions. The priming effects in lexical decision and the word frequency effects in initial processing measures in silent reading for both word types were taken as evidence of common lexical processing for function and content words. The observed differences in later processing measures in the eye-movement data were taken as evidence of differences in the role that the two word types have in sentence processing beyond the lexical level.

Attention↗
PubMed1998

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.

Adult↗
PubMed1995

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.

Adult↗
PubMed1994

Lexical and message-level sentence context effects on fixation times in reading.

Readers' eye movements were recorded as they read an unambiguous noun in a sentence context. In Experiment 1, fixation durations on a target noun were shorter when it was embedded in context containing a subject noun and a verb that were weakly related to the target than when either content word was replaced with a more neutral word. These results were not affected by changes in the syntactic relations between the content words. In Experiment 2, the semantic relations between the message-level representation of the sentence and the target word were altered whereas the lexical content was held constant. Fixation time on the target word was shorter when the context was semantically related to the target word than when it was unrelated. Intralexical priming effects between the subject noun and the verb were also observed. The results suggest that both lexical and message-level representations can influence the access of an individual lexical item in a sentence context.

Eye Movements↗
PubMed1992

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.

Humans↗
PubMed1992

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.

Eye Movements↗
PubMed1990

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 reader's 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.

Adult↗
PubMed1990

Elaborative inferencing as an active or passive process.

O'Brien, Shank, Myers, and Rayner (1988) reported that readers generated elaborative inferences only when a text contained characteristics that virtually eliminated the possibility of an inference being disconfirmed. We reanalyzed the data of O'Brien et al. (1988) and also conducted an experiment in which we varied (a) whether or not there was an anaphoric relation between a target word and its prior mention in the text and (b) the explicitness of the prior mention. Two refinements to O'Brien et al.'s conclusions are offered. First, the two text characteristics they manipulated (a strong biasing context or a demand sentence) may have produced different types of elaborative inferencing. We argue that a biasing context results in a passive form of elaborative inferencing, involving setting up a context of interpretation, whereas the presence of a demand sentence invites the reader to actively predict a subsequent expression. Second, clear evidence for either type of inference will be apparent only with truly anaphoric materials.

Attention↗
PubMed1989

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.

Adult↗
PubMed1987

Lesions in the preoptic area suppressed sexual receptivity in ovariectomized rats with estrogen implants in the ventromedial hypothalamus.

The objective of the experiment was to determine if electrolytic ablation of a portion of the preoptic area (POA) influenced the activation of female lordosis behavior by implants of estradiol benzoate in the ventromedial hypothalamus (VMH) of ovariectomized (OVX) rats. Two weeks after ovariectomy, rats received either bilateral electrolytic lesions (2 mA for 10 sec in Experiment 1, or 1 mA for 5 sec in Experiment 2) in the POA, or sham lesions (all procedures except passage of current). On the same day (day 0 of the experiment) thirty-gauge stainless steel cannulae containing crystalline estradiol benzoate were stereotaxically placed bilaterally into the VMH of all the rats. Subsequently, females were tested for the lordosis response to stud males on days 2, 4, 6, 8, and 10 in Experiment 1 or on days 7, 14 and 15 in Experiment 2. All rats received 0.5 mg progesterone (SC) only before the last test. A female was considered sexually receptive if she exhibited a lordosis quotient (LQ) greater than or equal to 10 (LQ = No. lordosis responses/10 mounts by male X 100). The frequencies for sexual receptivity in females with POA lesions were significantly lower than those for control females without lesions in both experiments. Additionally the degree of receptivity (lordosis quotient) was significantly lower on each test day for rats with POA lesions than that for rats without POA lesions. The results imply that the maintenance of the integrity of the POA under this experimental condition was important for the expression of the facilitative influence of the VMH on lordotic responsiveness.

Animals↗