Aphasic performance on a lexical decision task: multiple meanings and word frequency

The lexical access of words varying in the number of meanings and frequency of occurrence was examined in fluent and nonfluent aphasic individuals and a control group of non-brain-damaged adults, using a lexical decision task. Fluent aphasic subjects performed similarly to nonfluent aphasic and normal subjects, showing that words with a high number of meanings and with a high frequency of occurrence were recognized as real words faster than words with few meanings or a low frequency of occurrence. While previous research has demonstrated that the number of meanings associated with a word exerts a powerful influence on the internal lexicon of normals, the results of this study suggest that brain damage resulting in aphasia does not disrupt this semantic organization.     

Lexical ambiguity, semantic context, and visual word recognition.

Some alternative hypotheses about the recognition of ambiguous words are considered. According to the selective-access hypothesis, prior semantic context biases people to access one meaning of an ambiguous word rather than another in lexical memory during recognition. In contrast, the nonselectiveaccess hypothesis states that all meanings of the word are accessed regardless of the context. We tested certain versions of these hypotheses by having students decide whether selected strings of letters were English words. The stimuli included test sequnces of three words in which the second word had two distinct possible meanings, whereas the first and third words were related to these meanings in various ways. When the first and third words were related to the same meaning of the ambiguous second word (e.g., SAVE-BANK-MONEY), the reaction time to recognize the third word decreased. But when the first and third words were related to different meanings of the second word (e.g., RIVER-BANK-MONEY), the reaction time for the third word was not reliably different from a control sequence with unrelated words. These and other data favor the selective-access hypothesis. Selective access to lexical memory is discussed in relation to models of word recognition.     

Words, pictures, and priming: on semantic activation, conscious identification, and the automaticity of information processing

We investigated the encoding mechanisms involved in the perceptual recognition of words and pictures. Latencies in naming word and picture targets were analyzed as a function of several characteristics of a preceding prime, including whether it was a word or a picture, its duration of exposure, the interval between the prime and target onset, and whether or not the prime was consciously identified and reported by the subject. Results indicated that a common semantic code is available that can represent the meaning of either a word or a picture. This semantic representation, however, appears to be more easily activated by picture primes than by word primes and seems to benefit the naming of picture targets more than the naming of word targets. Despite the advantage for pictures with respect to semantic activation, overall processing in the naming task was slower and more attention demanding for pictures than for words. Comparison of our data with data on classification, in which an opposite pattern occurs (overall processing appears to be slower and more attention demanding for words than for pictures), suggests that, on the average, pictures have faster and more automatic access to their meanings than to their names but that words have faster and more automatic access to their names than to their meanings. This conclusion concerning the relative ability of stimuli to activate different kinds of internal representations has implications for a theory of the basis and development of automaticity.     

Automatic access of the meanings of ambiguous words in context: Some limitations of knowledge-based processing

Five experiments are described on the processing of ambiguous words in sentences. Two classes of ambiguous words (noun-noun and noun-verb) and two types of context (priming and nonpriming) were investigated using a variable stimulus onset asynchrony (SOA) priming paradigm. Noun-noun ambiguities have two semantically unrelated readings that are nouns (e.g., PEN, ORGAN); noun-verb ambiguities have both noun and verb readings that are unrelated (e.g., TIRE, WATCH). Priming contexts contain a word highly semantically or associatively related to one meaning of the ambiguous word; nonpriming contexts favor one meaning of the word through other types of information (e.g., syntactic or pragmatic). In nonpriming contexts, subjects consistently access multiple meanings of words and select one reading within 200 msec. Lexical priming differentially affects the processing of subsequent noun-noun and noun-verb ambiguities, yielding selective access of meaning only in the former case. The results suggest that meaning access is an automatic process which is unaffected by knowledge-based (“top-down”) processing. Whether selective or multiple access of meaning is observed largely depends on the structure of the ambiguous word, not the nature of the context.     

Lexical complexity and fixation times in reading: Effects of word frequency,verb complexity,and lexical ambiguity

Two experiments investigated whether lexical complexity increases a word’s processing time. Subjects read sentences, each containing a target word, while their eye movements were monitored. In experiment 1, mean fixation time on infrequent words was longer than on their more frequent controls, as was the first fixation after the Infrequent Target. Fixation Times on Causative, factive, and negative verbs and ambiguous nouns were no longer than on their controls. Further analyses on the ambiguous nouns, however, suggested that the likelihood of their various meanings affected fixation time. This factor was investigated in experiment 2. subjects spent a longer time fixating ambiguous words with two equally likely meanings than fixating ambiguous words with one highly likely meaning. The results suggest that verb complexity does not affect lexical access time, and that word frequency And the presence of two highly likely meanings may affect lexical access and/or postaccess integration.     

Spared access to idiomatic and literal meanings: a single-case approach

The current study examines how patients with aphasia access the meanings of idioms during spoken sentence comprehension. In our experiment, we had 4 subjects whose native language is German: 2 left-hemisphere damaged patients (Wernicke's and global aphasia); 1 right-hemisphere damaged patient; and 1 age-matched healthy speaker. Ambiguous two-element German noun compounds carrying an idiomatic as well as a literal meaning served as target words. While listening to contextually biasing sentences containing the target words, the subjects performed a lexical decision task at the offset of each compound. All the subjects, including the aphasic patients, accessed the compounds' literal and idiomatic meanings simultaneously despite the existence of contextually biasing sentences. The data are discussed by taking account of the findings of recent studies of lexical semantic processing in aphasia.     

无语境条件下汉语词类歧义词的意义激活

以单字词为实验材料,采用启动命名任务,在孤立词条件下考察了汉语词类歧义词不同意义激活的时间进程特点。实验发现,歧义词的两种意义都能被激活,但主要意义激活得较早,次要意义激活速度较慢;当两种意义都激活之后,次要意义的激活水平降低,而主要意义仍维持在一定激活水平。结果表明,汉语词类歧义词的多重激活过程会受到意义相对频率的影响。     

A word’s meaning affects the decision in lexical decision

The influence of an isolated word’s meaning on lexical decision reaction time (RT) was demonstrated through four experiments. Subjects in two experiments made lexical decision judgments, those in a third experiment pronounced the words used in the lexical decision task, and those in a fourth experiment quickly pronounced their first associative response to the words. Differences in lexical access time for the words were measured with the pronunciation task, and differences in meaning were assessed with the association task. Multiple regression analyses of lexical decision RT were conducted using associative RT, pronunciation RT, and other target word properties (printed frequency, length, instance dominance, and number of dictionary meanings) as predictor variables. These analyses revealed a relationship between lexical decision RT and associative RT after the effects of other variables had been partialed out. In addition, word frequency continued to have a significant relationship to lexical decision RT beyond that shared with pronunciation RT and the other variables. The results of these experiments indicate that at least some of the effect of word meaning and word frequency in lexical decision is attributable to a decision stage following lexical access.     

Processing idioms with multiple meanings

Three experiments are presented that examine understanding of idioms with one or more meaning. The results of Experiment 1 showed that subjects took longer to read and make paraphrase judgments for idioms when both their idiomatic and literal meanings are intended than it did to comprehend idioms meant only literally or idiomatically. In Experiments 2 and 3, subjects were faster at making phrase classification judgments for idioms with several different nonliteral interpretations than they were to make the same judgments for idioms with only one idiomatic interpretation. These findings suggest that idioms with more entries in the mental lexicon are accessed faster because it is more likely that one of their meanings will be encountered in a short time. The data overall support the idea that idioms are represented differently depending on their number of associated meanings.This research was supported by a Faculty Research Grant from the University of California, Santa Cruz. We wish to thank Dennis Johnston for his assistance in running subjects.     

Lexical search speed in children and adults

The retrieval of words from lexical memory was investigated in kindergartners (Age 6), first-graders (Age 7), third-graders (Age 9), and adults. A lexical decision task with auditorily presented words and nonwords was used, with decision latency as the dependent variable. Multiple regression analyses were used to examine the effects of word frequency, age of word acquisition, and number of word meanings. Results showed that word frequency contributed to decision latency for all age groups, age of word acquisition contributed to all groups but the third-grade subjects, and number of word meanings did not contribute for any age group. Results are discussed in relation to a model of the lexicon in children and adults. It is suggested that factors from the external linguistic community are internalized in the lexicon at an early age.     

Accessing lexical ambiguities during sentence comprehension: Effects of frequency of meaning and contextual bias

Two hypotheses concerning the nature of lexical access, the exhaustive access and the terminating ordered search hypotheses, were examined in two separate studies using a crossmodal lexical priming task. In this task, subjects listened to sentences that were biased toward either the primary interpretation (a meaning occurring 75% or more of the time) or a secondary interpretation (a meaning occurring less than 25% of the time) of a lexical ambiguity that occurred in each sentence. Simultaneously, subjects made lexical decisions about visually presented words. Decisions to words related to both the primary and secondary meanings of the ambiguity were facilitated when presented immediately following occurrence of the ambiguity in the sentence. This effect held under each of the two biasing context conditions. However, when they were presented 1.5 sec following occurrence of the ambiguity, only visual words related to the contextually relevant meaning of the ambiguity were facilitated. These results support the exhaustive access hypothesis. It is argued that lexical access is an autonomous subsystem of the sentence comprehension routine in which all meanings of a word are momentarily accessed, regardless of the factors of contextual bias or bias associated with frequency of use.     

The Processing of Grammatical Gender and Number in Spanish

The aim of the present study is to explore the representation and processing of inflectional morphology in Spanish. Experiment 1 compared the access time for words from the same base morpheme contrasted by the surface frequency of the masculine and feminine form, i.e., masculine-dominant items and feminine-dominant items. The results showed a surface frequency effect in both types of items. Experiment 2 compared the access time for masculine words having the same surface frequency but differing in their summed frequency (masculine plus feminine forms), the results showing no significant effect of this parameter. Finally, experiment 3 compared the access time for words from the same stem and contrasting by the surface frequencies for the singular and plural forms, i.e., singular-dominant and plural-dominant words. A clear frequency effect was observed for the singular-dominant words but not for plural-dominant ones. These results suggest that gender information is stored in the corresponding lexical entry and accessed from the full word form whereas the information about number is accessed from the stem corresponding to the singular form.     

The role of phonology in the activation of word meanings during reading: evidence from proofreading and eye movements.

Six experiments explored the role of phonology in the activation of word meanings when words were embedded in meaningful texts. Specifically, the studies examined whether participants detected the substitution of a homophone mate for a contextually appropriate homophone. The frequency of the incorrect homophone, the frequency of the correct homophone, and the predictability of the correct homophone were manipulated. Also, the impact of reading skill was examined. When correct homophones were not predictable and participants had a range of reading abilities, the evidence indicated that phonology plays a role in activating the meanings of low-frequency words only. When the performance of good and poor readers was examined separately, the evidence indicated that good readers primarily activate the meanings of words using the direct route, whereas poor readers primarily activate the meanings of words using the phonological route.     

Reading homographs: orthographic, phonologic, and semantic dynamics

Reading processes were compared across 3 word types: homographs (separate pronunciations and meanings, such as lead), homonyms (singular pronunciations but separate meanings, such as spring), and control words (e.g., clock). In Experiment 1, naming reaction times were significantly slower to homographs than to all other words. Experiments 2 and 3 used an association judgment task, with referent words related to the dominant or subordinate meanings of homonyms and homographs. In Experiment 2, homonyms and homographs were presented 1st, followed by disambiguating associates. In Experiment 3, presentation order was reversed. For homographs, performance costs always occurred for subordinate meanings. For homonyms, these costs vanished when context was provided by the preceding associates. The data underscore the priority of phonologic information in word meaning access and suggest that low- and high-level constraints combine to shape word perception.     

Effects of training on interpretation of emotional ambiguity

In four experiments we investigated whether interpretative biases found in anxious patients and high-trait anxious individuals can be induced by training in unselected volunteers. Repeated exposure to emotionally valenced (threatening) meanings of homographs during training was followed by relatively faster resolution of word fragments and faster lexical decisions for targets that matched the trained valence. Similar effects were found whether participants generated the meanings themselves, or verified a particular meaning of the homograph. Finally, comparison with a baseline condition confirmed that systematic exposure to threatening-but not non-threatening-resolutions of ambiguous words led to generally faster access times for congruent meanings, thus resembling the interpretative bias seen in anxiety states.     

Lexical access of function versus content words

There has been a simmering debate as to whether evidence exists for differential processes of lexical access for function and content words. This has centered around the frequency effect (higher word frequency reducing access times for content words but not function words). Previous work has used the lexical decision paradigm, which has been shown to reflect more than lexical access times. We measured naming times for words in sentences read for meaning. Our findings confirm that lexical access for function words is indeed faster than for content words as predicted by neurolinguistic theory and electrophysiological evidence, but that this difference can be attributed to word predictability (Cloze value) and word familiarity (log frequency). We also show that differences in frequency effect for the two word types holds only for the lower frequency words and not at all for the higher frequency words. We discuss the implications of the results for neurolinguistic theory.     

Determinants of the word-frequency effect in recognition memory

Possible determinants of the word-frequency effect (WFE), that is, the finding that lowfrequency (LF) words are recognized more accurately than high-frequency (HF) words, are evaluated. Three studies examined the view that, since HF words have more meanings than LF words, it is less likely that the word sense tagged at time of presentation will be accessed at time of test and a correct response will be made. To ensure the same word sense was accessed at time of presentation and time of test in the case of both HF and LF words, sentence contexts used during presentation were combined with cuing procedures at time of test. Recognition performance improved, but the WFE was unaltered even when the identical sentence context was used during presentation and test. A fourth study considered GlarLzer and Bowles’ (19761 suggestion that associates of both HF and LF words tend to be HF words that are (1)likely to be activated and derivatively encoded during presentation and (2) likely to include a number of distractors from the recognition test sufficient to impair performance on HF words. Analysis of associative responses of subjects to HF and LF words, and the errors they made, support strongly such an interference-type interpretation of the WFE.     

Syntactic context and lexical access

Recent studies demonstrating that multiple meanings of an ambiguous word are initially accessed even when only one reading is syntactically appropriate with the preceding context can be criticized on at least two grounds. First, many of the syntactic contexts used were not truly restrictive, and, secondly, subjects may not have had time to integrate the context before processing the ambiguous word. In the present study, subjects listened to a sentence ending in an ambiguous word and then made a lexical decision to a target related to either the appropriate or inappropriate reading. Contexts were completely restrictive, and a pause was introduced between the context and the ambiguous word. Multiple access still obtained, providing further support for the claim that lexical access is not guided by syntactic context.     

汉语单字词的通达:词频和累计频率的作用

用字判断任务考察单字词的词频和累计频率(字频)的作用。实验一发现单字词有词频效应,词频和词素频率没有交互作用。实验二同时发现了累计频率和词频的作用。结果表明单字词的词素频率被部分累计,其词频和累计频率共同影响其加工,支持了汉语词汇加工的双频作用特点,也为匹配汉字频率提供了新的证据。