Ulrich Hans Frauenfelder

Constraining psycholinguistic models of morphological processing and representation: The role of productivity

Listeners can understand novel lexical forms without apparent difficulty. This ability to analyze and interpret an unfamiliar input string raises some important psycholinguistic questions. We are led to ask how this parsing is actually accomplished and what its role is in the recognition of familiar word forms. The Standard psycholinguistic answer to the latter question has been that the human parsing abilities at the lexical level are of only minor importance. Indeed, in modeling lexical processing, psycholinguists have not been particularly concerned with morphological productivity and its implications for lexical processing and storage. This neglect of productivity is clearly apparent in the default view of language comprehension which is assumed to be based upon two radically different processing mechanisms. The first is exploited during word recognition and involves retrieving information from a permanent memory store, the lexicon. The second mechanism allows the integration of the semantic and syntactic information associated with the individually recognized words and their order. These latter processes parse and construct novel sentential representations. Thus, the mechanisms that are capable of generating new linguistic structure are typically reserved for the post-lexical processes.

The process of spoken word recognition: An introduction

This introduction sets the stage for the papers making up this special issue. Its focus is on two major problems in the study of lexical processing-determining the phases involved in recognising a spoken word and identifying the nature of different types of contextual influences on these phases. An attempt is made to decompose the process of recognising a word into phases which have both theoretical and empirical consequences. A similar analytic approach is taken in the discussion of the problem of context effects by distinguishing qualitatively different types of context (lexical, intra-lexical, syntactic, semantic, and interpretative). We argue that such an approach is necessary to make explicit the relationship between a particular type of contextual information and the phase(s) of processing at which it has its impact.

Phoneme monitoring and lexical processing: evidence for associative context effects.

In this paper, we propose a new version of the phoneme monitoring task that is well-suited for the study of lexical processing. The generalized phoneme monitoring (GPM) task, in which subjects detect target phonemes appearing anywhere in the test words, was shown to be sensitive to associative context effects. In Experiment 1, using the standard phoneme monitoring procedure in which subjects detect only word-initial targets, no effect of associative context was obtained. In contrast, clear context effects were observed in Experiment 2, which used the GPM task. Subjects responded faster to word-initial and word-medial targets when the target-bearing words were preceded by an associatively related word than when preceded by an unrelated one. The differential effect of context in the two versions of the phoneme monitoring task was interpreted with reference to task demands and their role in directing selective attention. Experiment 3 showed that the size of the context effect was unaffected by the proportion of related words in the experiment, suggesting that the observed effects were not due to subject strategies.

Bidirectional grapheme-phoneme activation in a bimodal detection task.

A divided attention paradigm was used to investigate whether graphemes and phonemes can mutually activate or inhibit each other during bimodal processing. In 3 experiments, Dutch subjects reacted to visual and auditory targets in single-channel or bimodal stimuli. In some bimodal conditions, the visual and auditory targets were nominally identical or redundant (e.g., visual A and auditory /a/); in others they were not (e.g., visual U and auditory /a/). Temporal aspects of cross-modal activation were examined by varying the stimulus onset asynchrony of visual and auditory stimuli. Cross-modal facilitation--but not inhibition--occurred rapidly and automatically between phoneme and grapheme representations. Implications for current models of bimodal processing and word recognition are discussed.

Grapheme Context Effects on Phonemic Processing

This study investigated the structural and temporal relationship between graphemic and phonemic processing by means of a cross-modal priming procedure. Subjects made a forced choice on the identity of the vowel in an auditorily presented syllable. To determine if and when phonemic representations are automatically activated by graphemes, visual letter primes were presented before, during, or after presentation of the syllable. in the indirect priming condition, the relationship (congruent/incongruent) between the letter and the consonant adjacent to the vowel was manipulated, whereas in the direct priming condition that between the letter and the target vowel itself was varied. in two indirect priming experiments faster reaction times were obtained over the entire range of SOAs tested when the prime was congruent with the consonant of the syllable, than when it was not. in a third direct priming experiment SOA-dependent facilitation effects were found with respect to a bimodal baseline-condition when the prime was congruent with the target vowel, and inhibition effects when it was congruent with the competing target vowel. The results support the hypothesis of automatic grapheme-to-phoneme activation before word recognition.

Word recognition—uniqueness or deviation? A theoretical note.

The structure and distribution of entries in the lexicon impose strong constraints on word recognition. A construct of value in operationalizing such constraints is that of uniqueness point Computed by reference to a phonetic dictionary, it is the earliest moment at which a word can be uniquely distinguished from all others in terms of a sequential phoneme by phoneme comparison. There is empirical evidence that the uniqueness point bears a close relationship to the recognition point, the moment at which a word can actually be recognized on the basis of incoming acoustic information. In reality, recognition depends upon noisy and unreliable acoustic information, making categorial phonetic decisions difficult, and the value of a uniqueness point, questionable. Minimal deviation is proposed as a new construct to represent the extent of mismatch between a given word and the closest non-identical word in the lexicon. A computer analysis of a large phonetic dictionary shows that on average minimal deviation increases almost constantly with stimulus input subsequent to the uniqueness point. This simulation suggests that the empirical success of the uniqueness point as an indicator of word recognition performance may be accounted for by this subsequent increase in deviation in addition to the single mismatch at the uniqueness point itself

The Word Frequency Effect for Open- and Closed-Class Items

Abstract A previous attempt (Segui, Mehler, Frauenfelder,&Morton, 1982) to assess in French the putative computational asymmetry between open- and closed-class words failed to reveal a difference in frequency sensitivity for these two types of words. In the present paper, two further lexical decision experiments are presented. The experimental conditions were chosen to maximise the chances of finding differences in frequency sensitivity between the two word classes (speeded responses and stimulus masking). Both experiments revealed strong frequency effects for open- and closed-class items and thus no asymmetry in frequency sensitivity. The implications of these results for both normal and aphasic populations are discussed.

Modeling form similarity in the mental lexicon with self-organizing feature maps

This paper describes recent efforts to model the remarkable ability of humans to recognize speech and words. Different techniques for representing phonological similarity between words in the lexicon with self-organizing algorithms are discussed. Simulations using the Standard Kohonen algorithm are presented to illustrate some problems confronted with this technique in modeling similarity relations of form in the human mental lexicon. Alternative approaches that can potentially deal with some of these limitations are sketched.

Structure and Computation in the Human Mental Lexicon

This chapter examines some psycholinguistic issues raised in the study of language understanding. Questions concerning the structure of the mental lexicon and the nature of the computations that allow access to information stored in this lexicon are addressed. Research using the metaphor of lexical space and exploiting the lexical databases for Dutch and English is presented. The analysis of the similarity neighborhoods of words of different frequencies revealed a surprising pattern; common words have more neighbors than rare words and these neighbors are more frequent than those of rare words. This finding, when confronted with the word frequency effect, creates an apparent paradox that this paper attempts to resolve.