Local strategic control of information in visual word recognition.

In the present studies, we examined strategic flexibility in the use of lexical and sublexical information in Korean word recognition. Korean readers show a large frequency effect for words printed in the alphabetic Hangul script only if these words are embedded in a list consisting largely of logographic (Hanza) words. In the first experiment, high- and low- frequency Hangul words were preceded by Hangul or Hanza words. Frequency effects were eliminated when a Hangul target word was preceded by two Hangul words, even when the overall proportion of Hanza words in the list was large. In the second experiment, one group saw each stimulus preceded by a cue indicating which script would be seen on that trial. Frequency effects for Hangul targets were absent under this condition, but were present when subjects were not so cued. These results indicate that Korean readers are able to control their use of lexical and sublexical information over a small number of stimuli or even trial by trial.

Regularity effects in word naming: what are they?

In a word-naming experiment, word-body consistency was crossed with grapheme-to-phoneme regularity to test predictions of current models of word recognition. In the latency and error data, a clear effect of consistency was observed, with the influence of regularity somewhat weaker. In addition, simulation data from three contemporary models of word recognition were obtained for the stimuli used in the experiment in order to compare the models' latencies with those of humans. The simulations showed that the human latency data are most consistent with the parallel-distributed-processing model of Plaut, McClelland, Seidenberg, and Patterson (1996), less so with the dual-process model (Zorzi, Houghton, & Butterworth, 1998), and least so with the dual-route-cascaded model (Coltheart & Rastle, 1994).

Age and the allocation of attention across the time course of word recognition.

Younger and older adults performed lexical decisions on ambiguous words, unambiguous words, and pseudowords, and simultaneously responded to an auditory probe presented at stimulus onset asynchronies (SOAs) of 90, 180, or 270 ms. For both age groups, lexical decisions and probe responses were faster for ambiguous words than for unambiguous words, and slowest for pseudowords. For the older adults, but not the younger adults, lexical decisions were slower when the probe was presented (the dual-task condition), compared with a control condition in which the lexical decision was performed alone. The older participants also showed slower tone-detection responses in the dual-task condition than when the tone was presented alone. For all participants, proportional tone-detection times (compared with tones in isolation) decreased with increasing SOA, but this decrease was less pronounced in the older group. Finally, the time between responses in the dual-task condition was longer for older than for younger adults. The results indicate that word meaning influences the allocation of attention similarly for younger and older adults, but that older adults suffer a cost and become disproportionately slower in processes related to response coordination and output.

Strategic reliance on phonological mediation in lexical access.

The present study investigated strategic variation in reliance on phonological mediation in visual word recognition. In Experiment 1, semantically related or unrelated word primes preceded word, pseudohomophone (e.g., trane), or nonpseudohomophone (e.g., trank) targets in a lexical decision task. Semantic priming effects were found for words, and response latencies to pseudohomophones were longer in related than in unrelated prime conditions. In Experiment 2, related or unrelated word primes preceded word or pseudohomophone targets. A relatedness effect was found for words, although it was significant at a 600-msec prime-target stimulus onset asynchrony (SOA) and not at a 200-msec SOA. There was no relatedness effect for pseudohomophones. Experiment 3 was a replication of Experiment 2, except that pseudohomophones were replaced by nonpseudohomophonic orthographic controls. Facilitation effects for related target words were greater in Experiment 3 than in Experiment 2. The results reflect apparent variations in the expectation that a related prime reliably indicates that a target is a word. Although reliance on phonological mediation might be strategically contingent, there could be a brief time period in which phonologically mediated lexical access occurs automatically. Whether phonological information is maintained or suppressed subsequently depends on its overall usefulness for the task.

Effects of association and imageability on phonological mapping.

In two experiments, we examined the influence of semantic activation on the generation of a phonological code, testing the interactivity assumption common to both dual-route and interactive-activation models. In Experiment 1, subjects named regular and irregular targets preceded by related and unrelated primes. In Experiment 2, these variables and target imageability were manipulated. Both relatedness and imageability interacted with regularity, indicating that semantic activity speeds access to a phonological code.

Effect of backward priming on word recognition in single-word and sentence contexts.

Backward priming was investigated under conditions similar to those used in lexical ambiguity research. Subjects received prime-target word pairs that were associated either unidirectionally (BABY-STORK) or bidirectionally (BABY-CRY). In the first experiment, targets were presented 500 ms following the onset of visual primes, and subjects made naming or lexical decision responses to the targets. Forward priming was obtained in all conditions, while backward priming (i.e., priming for pairs in which there was a unidirectional target-to-prime association, as in BABY-STORK) occurred only with lexical decision. In the second experiment, primes were presented auditorily, either in isolation or in a sentence. Targets followed the offset of the primes either immediately or after 200 ms. Backward priming occurred with both response tasks, but only when the prime was an isolated word. In addition, backward priming decreased over time with the naming task, but not with lexical decision. These results suggest that the locus of the backward priming effect is different for the two response tasks. Further, the lack of a backward priming effect with sentence contexts suggests that backward priming cannot account for the demonstrations of multiple access in the lexical ambiguity literature. These results, therefore, support a context-independent view of lexical access.

Lexical ambiguity and the timecourse of attentional allocation in word recognition.

In two experiments the allocation of attention during the recognition of ambiguous and unambiguous words was investigated. In Experiment 1, separate groups performed either lexical decision, auditory probe detection, or their combination. In the combined condition probes occurred 90, 180, or 270 ms following the onset of the lexical-decision target. Lexical decisions and probe responses were fastest for ambiguous words, followed by unambiguous words and pseudowords, respectively, which indicated that processing ambiguous words was less attention demanding than unambiguous words or pseudowords. Attention demands decreased across the timecourse of word recognition for all stimulus types. In Experiment 2, one group performed the lexical-decision task alone, whereas another group performed the lexical-decision task during the retention interval of a short-term memory task. The results were consistent with those from Experiment 1 and showed that word recognition is an attention-demanding process and that the demands are inversely related to the number of meanings of the stimulus. These results are discussed with regard to the structure of the mental lexicon (i.e., single vs. multiple lexical entries) and the effect of such a structure on attentional mechanisms.

Dual-task performance as a function of adult age and task complexity.

A dual-task procedure was used to examine capacity demands of letter-matching in younger and older adults. Older subjects generally were slower on both tasks than were younger adults, but this difference was especially pronounced for the late stages of category matching, suggesting that retrieval and comparison of category information is particularly demanding for older adults.

Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings.

Targets related to ambiguous primes were projected to the left and right visual fields in a lexical priming experiment with stimulus onset asynchronies (SOA) of 35 and 750 msec. Right visual field results were similar to our earlier results with central projection (G. B. Simpson & C. Burgess, 1985, Journal of Experimental Psychology: Human Perception and Performance, 11, 28-39). Facilitation was found for the more frequent meaning at both SOAs and a decrease in facilitation for the less frequent meaning at the longer SOA. In contrast, left visual field results indicated a decay of facilitation for the more frequent meaning at the longer SOA, while activation for the subordinate meaning increased. Results suggest that, while automatic processing occurs in both hemispheres, only the left hemisphere engages in controlled processing of ambiguous word meanings. In addition, the present results support the idea that the right hemisphere has a special role in ambiguity resolution and that the right hemisphere lexicon possesses a richer endowment than earlier thought.

Age differences in the rate of processing in short-term memory.

A probe-recognition task compared the speed and accuracy of visual, phonemic, and semantic recognition processes in younger and older adults. Each trial consisted of the sequential presentation of 10 words at a rate of either 350, 700, or 1400 msec per word. Following each study list, a probe word was given that could be identical to any word in the preceding study list or a homonym or a synonym. The two age groups were equivalent in their ability to identify recently presented identical words, homonyms , and synonyms. Age differences, however, were observed in the speed of access to information, and these differences were greatest on tasks requiring retrieval of semantic information from the secondary memory component of short-term memory.

Encoding and contextual components of word recognition in good and poor readers.

Good and poor readers from the third and sixth grades (9- and 12-year-olds, respectively), named visually presented words as rapidly as possible. Words were in clear or degraded form, and were preceded by related or unrelated words. Poor readers were hurt more by degradation than were good readers, and showed greater benefit from context. In general, the contextual benefit was greater with degraded words than with intact, and this interaction was especially pronounced in the poor readers. The results are consistent with an interactive-compensatory model of word recognition. Under conditions in which stimulus encoding is slow, contextual factors may compensate for this encoding deficit.

False recognition of static and dynamic object properties by preschool children.

A false recognition task was used to compare preschool children's use of static and dynamic properties of objects in semantic processing. Four, five, and six year old children heard a list of object names, and then were tested for recognition of these words with a recognition test list that included distractor words that were static or dynamic properties of the objects on the first list. False recognition scores of dynamic properties were higher than those for static, for 4 and 5 year old children, with no differences for 6 year old children. The results argue for a functional basis for the encoding of referential terms in memory, and are discussed in terms of two models of semantic development.