Subcategorical phonetic mismatches and lexical access.

The place of phonetic analysis in the perception of words is unclear. While some theories assume fully specified phonemic strings as input, other theories assume that little analysis occurs. An earlier experiment by Streeter and Nigro (1979) produced evidence, based on auditorily presented words with misleading acoustic cues, that lexical decisions were based on mostly unanalyzed patterns, since word judgments were delayed by misleading information whereas nonword judgments were not. The present studies expand that work to a different set of cues, and to cases in which the overriding cue came first. An additional task, auditory naming, was used to examine the effects when the decision stage is less demanding. For the lexical decision task, misleading information slowed the responses, for both words and nonwords. In the auditory naming task, only the slower responses were affected. These results suggest that phonetic conflicts are resolved prior to lexical access.     

Gradient effects of within-category phonetic variation on lexical access

In order to determine whether small within-category differences in voice onset time (VOT) affect lexical access, eye movements were monitored as participants indicated which of four pictures was named by spoken stimuli that varied along a 0-40 ms VOT continuum. Within-category differences in VOT resulted in gradient increases in fixations to cross-boundary lexical competitors as VOT approached the category boundary. Thus, fine-grained acoustic/phonetic differences are preserved in patterns of lexical activation for competing lexical candidates and could be used to maximize the efficiency of on-line word recognition.     

The effects of graphemic,phonetic, and semantic relationships on access to lexical structures

The question of whether or not lexical information is accessed directly from a visual code or by a process of phonetic mediation was investigated in three lexical decision experiments. Phonetic similarity influenced decisions about visually presented words only when they were to be discriminated from orthographically regular nonwords. When consonant strings or random letter strings were used as nonwords, phonetic similarity effects were absent, and graphemic similarity exerted a powerful effect while evidence of semantic priming was found. This pattern was interpreted as evidence of direct lexical access, which is probably the normal processing mode for skilled readers. Phonetic coding, when it occurs, may be a storage strategy rather than a part of the addressing chain for lexical structures.     

Probabilistic constraint satisfaction at the lexical/phonetic interface: evidence for gradient effects of within-category VOT on lexical access

Research in speech perception has been dominated by a search for invariant properties of the signal that correlate with lexical and sublexical categories. We argue that this search for invariance has led researchers to ignore the perceptual consequences of systematic variation within such categories and that sensitivity to this variation may provide an important source of information for integrating information over time in speech perception. Data from a study manipulating VOT continua in words using an eye-movement paradigm indicate that lexical access shows graded sensitivity to within-category variation in VOT and that this sensitivity has a duration sufficient to be useful for information integration. These data support a model in which the perceptual system integrates information from multiple sources and from the surrounding temporal context using probabilistic cue-weighting mechanisms.     

Effect of lexical status on phonetic categorization

To investigate the interaction in speech perception between lexical knowledge (in particular, whether a stimulus token makes a word or nonword) and phonetic categorization, sets of [bVC]-[dVC] place-of-articulation continua were constructed so that the endpoint tokens represented word-word, word-nonword, nonword-word, and nonword-nonword combinations. Experiment 1 demonstrated that ambiguous tokens were perceived in favor of the word token and supported the contention that lexical knowledge can affect the process of phonetic categorization. Experiment 2 utilized a reaction time procedure with the same stimuli and demonstrated that the effect of lexical status on phonetic categorization increased with response latency, suggesting that the lexical effect represents a perceptual process that is separate from and follows phonetic categorization. Experiment 3 utilized a different set of [b-d] continua to separate the effects of final consonant contrast and lexical status that were confounded in Experiments 1 and 2. Results demonstrated that both lexical status and contextual contrast separately affected the identification of the initial stop. Data from these three experiments support a perceptual model wherein phonetic categorization can operate separately from higher levels of analysis.     

Phonological recoding and lexical access

Four experiments are reported that examine the effects of homophony (e.g., SAIL/SALE) on response latency in a lexical decision task. The results indicated that an effect of homophony was evident only if the nonword distractors consisted of legal, pronounceable strings (e.g., SLINT), but that this effect disappeared if the nonwords sounded like English words (e.g., BRANE). An optional encoding strategy is proposed to account for this differential effect. It is suggested that while both graphemic and phonemic encoding occurred simultaneously, naive subjects tended to rely on the outcome of the phonological route. However, when such reliance produced a high error rate (i.e., when the nonwords sounded like English words),. these subjects were able to abandon a phonological strategy and rely on the graphemic encoding procedure instead. Two further aspects of the results are of interest. First, the less frequent member of a homophone pair was slower when compared with a control item if the nonword distractors were of the SLINT type, but not different if they were of the BRANE type. The high-frequency members did not differ from their controls in either nonword environment. Second, in a homophone “repetition” experiment, the frequency order of presentation within pairs of homophones (i.e., the high-frequency member followed by the low-frequency member, or vice versa) had a substantial effect. A spelling recheck procedure and a response-inhibitory mechanism are postulated to incorporate these effects into a dual-encoding direct-access model of word recognition.     

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.     

Effects of speaking rate and lexical status on phonetic perception

Among the contextual factors known to play a role in segmental perception are the rate at which the speech was produced and the lexical status of the item, that is, whether it is a meaningful word of the language. In a series of experiments on the word-initial /b/-/p/ voicing distinction, we investigated the conditions under which these factors operate during speech processing. The results indicated that under instructions of speeded responding, listeners could, on some trials, ignore some later occurring contextual information within the word that specified rate and lexical status. Importantly, however, they could not ignore speaking rate entirely. Although they could base their decision on only the early portion of the word, when doing so they treated the word as if it were physically short--that is to say, as if there were no later occurring information specifying a slower rate. This suggests that listeners always take account of rate when identifying the voicing value of a consonant, but precisely which information within the word is used to specify rate can vary with task demands.     

How social network heterogeneity facilitates lexical access and lexical prediction

People learn language from their social environment. As individuals differ in their social networks, they might be exposed to input with different lexical distributions, and these might influence their linguistic representations and lexical choices. In this article we test the relation between linguistic performance and 3 social network properties that should influence input variability, namely, network size, network heterogeneity, and network density. In particular, we examine how these social network properties influence lexical prediction, lexical access, and lexical use. To do so, in Study 1, participants predicted how people of different ages would name pictures, and in Study 2 participants named the pictures themselves. In both studies, we examined how participants’ social network properties related to their performance. In Study 3, we ran simulations on norms we collected to see how age variability in one’s network influences the distribution of different names in the input. In all studies, network age heterogeneity influenced performance leading to better prediction, faster response times for difficult-to-name items, and less entropy in input distribution. These results suggest that individual differences in social network properties can influence linguistic behavior. Specifically, they show that having a more heterogeneous network is associated with better performance. These results also show that the same factors influence lexical prediction and lexical production, suggesting the two might be related.     

Gender and lexical access in Bulgarian

Two procedures were used to explore the effects of semantic and grammatical gender on the recognition and processing of Bulgarian nouns, in relation to other factors that are known to affect lexical access. This study in a three-gender language was modeled on previous work in Italian, a two-gender language (Bates, Devescovi, Pizzamiglio, D'Amico, & Hernandez, 1995). Words were presented auditorily in randomized lists in two tasks: (1) repeat the word as quickly as possible and (2) determine the grammatical gender of the noun as soon as possible and indicate the decision by pressing a button. Reaction times in both tasks were influenced by phonological factors, word frequency, and irregularity of gender marking, but semantic and grammatical gender affected only gender monitoring. The significant contribution of semantic gender to processing in Bulgarian contrasts with previous findings for Italian. Also, we obtained an interaction between sex of the subject and noun gender, reflecting a bias toward one's own grammatical gender "counterpart" (especially for females). Reanalysis of the prior study in Italian showed a similar interaction but confirmed no effects of the semantic gender of the noun, suggesting that these two natural gender effects can dissociate. Possible reasons for cross-linguistic differences are discussed, with implications for comparative studies of gender and lexical access.     

Gender and lexical access in Italian

Two new procedures were employed to investigate the effects of semantic and grammatical gender on lexical access in Italian and to investigate the interaction of gender with other factors that are known to influence lexical access in other languages. The gender-monitoring task requires a conscious decision about the gender of each noun, whereas the word repetition task does not require explicit attention to gender. In both tasks, single words are presented out of context, under speeded conditions. Both procedures proved to be sensitive indices of word recognition, with reaction times that are closely tied to the point at which words can be uniquely identified (although some processing before and after the uniqueness point was seen). In both tasks, reaction times were strongly affected by phonological factors (e.g., length, number of syllables, and presence of frication on the initial consonant). Phonological transparency of gender marking had a reliable effect on gender monitoring but had no effect on word repetition, suggesting that explicit attention to gender may be a factor affecting utilization of this phonological cue. Semantic factors (including semantic gender) had no effect on performance. Frequency and age of acquisition had very small effects when other factors were controlled. Implications for current models of lexical access are discussed, with special reference to the role of gender.     

Orthographic neighborhood structure and lexical access

An experiment addressed whether lexical decision response latency and error rate are influenced by orthographic neighborhood structure. It was found that words with several higher-frequency neighbors were responded to more slowly and less accurately than words with fewer higher-frequency neighbors, even though the stimulus words were matched oh number of neighbors, word frequency, neighborhood frequency, number of higher-frequency neighbors, word length, and number of syllables. The results indicate that frequency is a relative effect dependent on the structure of the neighborhood. A word at the bottom of its neighborhood will be affected by the lexical representations of its higher-frequency neighbors. However, a word at the top of its neighborhood does not appear to be affected by the lexical representations of its neighbors.Preparation of this report was supported by a University Foundation Research Grant and an Affirmative Action Faculty Development Award from San Jose State University, to Laree Huntsman. The authors thank Brian Cronk, Katherine Lemkuil, Joseph Tajnai, Ruzica Udovicic, and Michael Weinborn for their assistance with stimuli development, Nadirah Ihsan and Jeffrey Limon for their assistance with data collection, and especially Guy Woffmdin for his invaluable programming assistance.     

Lexical morphology and lexical access.

Research on morphology in word recognition has been plagued by conflicting results (McQueen & Cutler, 1998, give a recent review). Some findings suggest that words are accessed as full forms, while others suggest that words are accessed in terms of their component morphemes. The answer may lie in the properties of the affixes themselves: Kiparsky's (1982) Lexical Phonology and Morphology assigns affixes in English to different "levels" of attachment, based on their productivity, order of attachment, and phonological interaction with roots. We present data suggesting that productive, phonologically neutral, semantically transparent "Level 2" suffixes are "decomposed" for analysis in some cases, but that words with idiosyncratic, structure-changing, semantically opaque "Level 1" suffixes are not.     

Recalibration of phonetic categories by lipread speech versus lexical information

Listeners hearing an ambiguous phoneme flexibly adjust their phonetic categories in accordance with information telling what the phoneme should be (i.e., recalibration). Here the authors compared recalibration induced by lipread versus lexical information. Listeners were exposed to an ambiguous phoneme halfway between /t/ and /p/ dubbed onto a face articulating /t/ or /p/ or embedded in a Dutch word ending in /t/ (e.g., groot [big]) or /p/ (knoop [button]). In a posttest, participants then categorized auditory tokens as /t/ or /p/. Lipread and lexical aftereffects were comparable in size (Experiment 1), dissipated about equally fast (Experiment 2), were enhanced by exposure to a contrast phoneme (Experiment 3), and were not affected by a 3-min silence interval (Experiment 4). Exposing participants to 1 instead of both phoneme categories did not make the phenomenon more robust (Experiment 5). Despite the difference in nature (bottom-up vs. top-down information), lipread and lexical information thus appear to serve a similar role in phonetic adjustments.     

Language blocking and lexical access in bilinguals

Two experiments are described which compared the effects of mixed- and pure-language lists on lexical decision times with English-French bilinguals. Experiment 1 showed that reaction times are faster in the pure-language presentation than in the mixed-language presentation with words that are orthographically legal letter strings in the other language. The second experiment tested this pure-mixed effect more precisely by comparing different sequences of two successive items and by introducing the language-specific orthography factor. No pure-mixed effect was found for words with language-specific orthographies. The pure-mixed effect was restricted to words containing no language-specific orthographic cues and to the different language sequences, that is, on trials following a language change. These results are not compatible with a selective search process that it strategically modified by pure-language presentation. The role of language-specific orthography in bilingual word recognition is discussed with regard to recent models of word recognition.     

Phonological processing and lexical access in aphasia

This study explored the relationship between on-line processing of phonological information and lexical access in aphasic patients. A lexical decision paradigm was used in which subjects were presented auditorily with pairs of words or word-like stimuli and were asked to make a lexical decision about the second stimulus in the pair. The initial phonemes of the first word primes, which were semantically related to the real word targets, were systematically changed by one or more than one phonetic feature, e.g., cat-dog, gat-dog, wat-dog. Each of these priming conditions was compared to an unrelated word baseline condition, e.g., nurse-dog. Previous work with normals showed that even a nonword stimulus receives a lexical interpretation if it shares a sufficient number of phonetic features with an actual word in the listener's lexicon. Results indicated a monotonically decreasing degree of facilitation as a function of phonological distortion. In contrast, fluent aphasics showed priming in all phonological distortion conditions relative to the unrelated word baseline. Nonfluent aphasics showed priming only in the undistorted, related word condition relative to the unrelated word baseline. Nevertheless, in a secondary task requiring patients to make a lexical decision on the nonword primes presented singly, all aphasics showed phonological feature sensitivity. These results suggest deficits for aphasic patients in the various processes contributing to lexical access, rather than impairments at the level of lexical organization or phonological organization.     

Terminating and exhaustive search in lexical access

Two experiments which test predictions derived from the assumption that lexical access involves a search process are reported. In the first experiment, test items must be classified as ambiguous or unambiguous, and in the second experiment, they are classified according to their syntactic properties. In both experiments, it is shown that when the target of the search is a nonexistent entry, an exhaustive search is involved, even though the test items are words. Further, in these conditions, frequency of occurrence is no longer related to decision time, as it is in lexical decision experiments. It is concluded that the search model adequately explains the procedure whereby the most common meaning of a homograph is accessed, but that the less common meaning is accessed in some completely different manner.     

Measuring lexical access during sentence processing

The results from “on-line” investigations of sentence comprehension are often difficult to interpret since it is not always apparent what component processes are reflected in the response measure. The results of two experiments reported here indicate that response latencies from phoneme-triggered lexical decision (PTLD) reflect the time needed for lexical access during sentence processing. Listeners were presented with sentences and were asked to make a word/nonword judgment for items beginning with a particular word-initial target phoneme. Speed of lexical access was manipulated by varying the semantic predictability of the target-bearing word. WORD judgments were faster for words that were preceded by semantically related verbs than were WORD judgments for words that were preceded by neutral verbs. The present results are consistent with other studies showing semantic facilitation of lexical access during the processing of fluent speech. It is argued that the phoneme-triggered lexical-decision task is a more suitable measure of lexical access during sentence processing than phoneme monitoring (Foss, 1969) or word monitoring (Marslen-Wilson & Tyler, 19751. In addition, it is pointed out that the phoneme-triggered lexical-decision task lends itself to modifications which should enable investigators to study various aspects of on-line sentence processing.     

Context and lexical access: implications of nonword interference for lexical ambiguity resolution

To eliminate potential "backward" priming effects, Glucksberg, Kreuz, and Rho (1986) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al. to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al. were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al. is due to postlexical judgements of the congruence of the sentence context and the target, not to context constraining lexical access.