Over the last 10 years, the assimilation process referred to as vowel harmony has served as a test case for a number of proposals in phonological theory. Current autosegmental approaches successfully capture the intuition that vowel harmony is a dynamic process involving the interaction of a sequence of vowels; still, no theoretical analysis has offered a non-stipulative account of the inconsistent behavior of the so-called "transparent", or disharmonic, segments. The current paper proposes a connectionist processing account of the vowel harmony phenomenon, using data from Hungarian. The strength of this account is that it demonstrates that the same general principle of assimilation which underiies the behavior of the "harmonic" forms accounts as well for the apparently exceptional "transparent" cases, without stipulation.

One example of linguistic productivity that has been much discussed in the developmental literature is the verb inflection system of English. Opinion is divided on the issue of whether regular^rregular distinctions in surface behavior must be attributed to an underlying distinction in the mechanisms of production. Looking at the course of historical development in English, the current paper evaluates potential shortcomings of two competing approaches. T w o sets of simulations are presented. The first argues that a single-mechanism model offers a natural account of historical facts that would be problematic for a dual mechanism approach. The second addresses a potential problem for a single-mechanism account, the question of default behavior, and demonstrates that even in the absence of superior type frequency a network is capable of developing a "default" category. W e conclude that the single network account offers a more promising mechanism for explaining English verb inflection.'

This paper describes a technique developed for modeling historical change in connectionist networks, and Wefly reviews previous work applying that technique to the problem of the historical development of the regular verb system from early to late Old English. W e then broaden the scope of the simulations and ask what the effect would be of having such changes occur in a single mechanism which is processing both the regular and inegular verbs, and extended over a longer time period. A s w e shall see, the results are highly consistent with the major historical developments. Furthermore, the results are readily under- stood in terms of network dynamics, and provide a ratio- nale for the shape of the attested historical changes.

We used a cross-modal repetition priming task to investigate the mental representation of regular and irregular past tense forms in English. Subjects heard a spoken prime (such as walked) immediately followed by lexical decision to a visual probe (such as walk). W e contrasted three types of English verbs, varying in the phonological and morphological regularity of their past tense inflection. These were (i) Regular verbs {jump/jumped), with the regular 1-61 inflection and no stem change, (ii) Semi-Weak verbs {burn/burnt, feel/felt), with irregular alveolar inflection and some phonologically regular stem vowel change, and (iii) Vowel Change verbs {sing/sang, give/gave), which mark past tense through phonologically irregular changes in the stem vowel. T h e stem forms of these verbs were presented in three prime conditions ~ preceded either by the Identity Prime, a Past Tense Prime, or a Control Prime. T h e Identity Prime significantly facilitated lexical decision responses for all three verb classes, but the Past Tense Prime, while significantly facilitating responses in the Regular verb class, produced no overall effect for the Semi-Weak verbs, and significant interference for the Vowel Change verbs. W e conclude that phonological irregularity in the relation between a stem and an inflected form can lead to very different lexical structures than w e find for more regular phonological relationships.

In a series of experiments. Bock and colleagues have demonstrated that subjects show a reliable increase in the use of particular syntactic constructions after having heard and repeated that construction in an unrelated sentence. Aspects of the data seem to indicate that it is syntactic constituent structure, independent of meaning, that underlies the facilitation in these situations. In this study we investigate whether more semantic factors might also lead to priming, and specifically whether the assignment of a semantic role to a particular participant in a prime sentence can increase the probability of a target sentence whose structure allows a similar assignment. To test this we replicate Bock's study and include a further set of primes (provide-with primes) which have the syntactic constituent structure of the dative, but share semantic role assignment with the ditransitive. If syntactic priming were triggered by constituent structure alone, primes like this would lead to more dative responses, relative to a ditransitive prime. If semantic involvement were crucial, on the other hand, this prime should elicit more ditransitive responses. In this study we find significantly more ditransitive responses following the provide-with sentence than following a dative prime, and no difference between the provide-with and ditransitive primes, suggesting that semantic factors indeed play a role.