Kenneth I. Forster

DMDX: A Windows display program with millisecond accuracy

DMDX is a Windows-based program designed primarily for language-processing experiments. It uses the features of Pentium class CPUs and the library routines provided in DirectX to provide accurate timing and synchronization of visual and audio output. A brief overview of the design of the program is provided, together with the results of tests of the accuracy of timing. The Web site for downloading the software is given, but the source code is not available.

REPETITION PRIMING AND FREQUENCY ATTENUATION IN LEXICAL ACCESS

Repetition priming effects in lexical decision tasks are stronger for low-frequency words than for high-frequency words. This frequency attenuation effect creates problems for frequency-ordered search models that assume a relatively stable frequency effect. The suggestion is made that frequency attenuation is a product of the involvement of the episodic memory system in the lexical decision process. This hypothesis is supported by the demonstration of constant repetition effects for high- and low-frequency words when the priming stimulus is masked; the masking is assumed to minimize the influence of any possible episodic trace of the prime. It is further shown that long-term repetition effects are much less reliable when the subject is not required to make a lexical decision response to the prime. When a response is required, the expected frequency attenuation effect is restored. It is concluded that normal repetition effects consist of two components: a very brief lexical effect that is independent of frequency and a long-term episodic effect that is sensitive to frequency. There has been much recent interest in the fact that in a lexical decision experiment, where subjects are required to classify letter strings as words or nonwords, there is a substantial increase in both the speed and the accuracy of classificatio n for words that are presented more than once during the experiment, even though considerable time may have elapsed between successive presen

Lexical Access and Naming Time.

Naming times and word-nonword classification times (lexical decision times) for samples of words, nonwords, and unfamiliar words were compared. It was found that naming times for words were shorter than for nonwords, and that naming times for high frequency words were shorter than for low frequency words, indicating that word naming occurred as a result of a lexical search procedure, rather than occurring prior to lexical search. It was also found that there was a positive correlation between naming times and lexical decision times for words, but not for nonwords. The results are discussed in terms of their implications for the phonemic recoding hypothesis of Rubenstein, Lewis, and Rubenstein (1971) .

LEXICAL STORAGE AND RETRIEVAL OF PREFIXED WORDS

Three experiments are described which support the hypothesis that in a lexical decision task, prefixed words are analyzed into their constituent morphemes before lexical access occurs. The results show that nonwords that are stems of prefixed words (e.g., juvenate ) take longer to classify than nonwords which are not stems (e.g., pertoire ), suggesting that the nonword stem is directly represented in the lexicon. Further, words which can occur both as a free and as a bound morpheme (e.g., vent ) take longer to classify when the bound form is more frequent than the free form. Finally, prefixed nonwords took longer to classify when they contained a real stem (e.g., dejuvenate ), compared with control items which did not (e.g., depertoire ). A general model of word recognition is presented which incorporates the process of morphological decomposition.

Syntactically based sentence processing classes: Evidence from event-related brain potentials

Theoretical considerations and diverse empirical data from clinical, psycholinguistic, and developmental studies suggest that language comprehension processes are decomposable into separate subsystems, including distinct systems for semantic and grammatical processing. Here we report that event-related potentials (ERPs) to syntactically well-formed but semantically anomalous sentences produced a pattern of brain activity that is distinct in timing and distribution from the patterns elicited by syntactically deviant sentences, and further, that different types of syntactic deviance produced distinct ERP patterns. Forty right-handed young adults read sentences presented at 2 words/sec while ERPs were recorded from over several positions between and within the hemispheres. Half of the sentences were semantically and grammatically acceptable and were controls for the remainder, which contained sentence medial words that violated (1) semantic expectations, (2) phrase structure rules, or (3) WH-movement constraints on Specificity and (4) Subjacency. As in prior research, the semantic anomalies produced a negative potential, N400, that was bilaterally distributed and was largest over posterior regions. The phrase structure violations enhanced the N125 response over anterior regions of the left hemisphere, and elicited a negative response (300-500 msec) over temporal and parietal regions of the left hemisphere. Violations of Specificity constraints produced a slow negative potential, evident by 125 msec, that was also largest over anterior regions of the left hemisphere. Violations of Subjacency constraints elicited a broadly and symmetrically distributed positivity that onset around 200 msec. The distinct timing and distribution of these effects provide biological support for theories that distinguish between these types of grammatical rules and constraints and more generally for the proposal that semantic and grammatical processes are distinct subsystems within the language faculty.

Lexical storage and retrieval of polymorphemic and polysyllabic words.

Abstract Five experiments are deseribed which examine how polysyllabic words (e.g., DAY-DREAM, ATHLETE) are stored and retrieved from lexical memory. The first four experiments look at interference effects caused by the accessing of inappropriate lexical entries. It is found that compound nonwords whose first constituent is a word (e.g., DUSTWORTH, FOOTMILGE) take longer to classify as nonwords than compound nonwords whose first constituent is not a word (e.g., TROWBREAK, MOWDFLISK). Moreover, the presence of a word in the second constituent position appears to be irrelevant. These effects hold even when the boundary between constituents is unclear on an orthographic basis (e.g., TRUCERIN). It is also argued that first syllables, as opposed to last syllables, have independent status in the lexicon since nonword first syllables (e.g., ATH) show interference effects, while last syllables (e.g., CULE) do not. The fifth experiment reveals that the frequency of the first constituent of a compound word influences classification times. The results point to the conclusion that polysyllabic words, regardless of whether they are polymorphemic or monomorphemic, are accessed via their first syllable.

Priming and the effects of sentence and lexical contexts on naming time evidence for autonomous lexical processing

Models of language processing which stress the autonomy of processing at each level predict that the semantic properties of an incomplete sentence context should have no influence on lexical processing, either facilitatory or inhibitory. An experiment similar to those reported by Fischler and Bloom (1979) and Stanovich and West (1979, 1981) was conducted using naming time as an index of lexical access time. No facilitatory effects of context were observed for either highly predictable or semantically appropriate (but unpredictable) completions, whereas strong inhibitory effects were obtained for inappropriate completions. When lexical decision time was the dependent measure, the same results were obtained, except that predictable completions now produced strong facilitation. In a further experiment the inhibitory effects of context on lexical decision times for inappropriate targets were maintained, even though unfocussed contexts were used, in which no clear expectancy for a particular completion was involved. These results were interpreted in terms of a two-factor theory which attributes the facilitation observed with the lexical decision task to postaccess decision processes which are not involved in the naming task. The inhibitory effects were attributed to interference resulting from semantic integration. In contrast to the results for sentence contexts, lexical contexts of the doctor-nurse variety produced clear facilitation effects on naming time (but no inhibitory effects). It was also shown that relatively minor variations in the type of neutral context could completely alter the relative importance of facilitation and inhibition.

Masked priming with graphemically related forms: Repetition or partial activation?

Form-priming occurs when a prime that is graphemically similar to the target word facilitates processing of the target. In an activation model (such as Mortons logogen model), such an effect can be interpreted as a partial-activation effect. A prime that shares letters with the target must inevitably produce activation in the detectors for both the prime and the target. Alternatively, form-priming could be seen as a special case of repetition-priming, in which the prime actually accesses the entry for the target. It is shown that masked-priming effects in the lexical decision task can be obtained for graphemically related pairs such as bontrast-CONTRAST, but not for four-letter pairs such as bamp-CAMP. It is suggested that the priming effect is controlled by neighbourhood density, short words usually having many neighbours, long words having very few. This hypothesis is supported by the finding that form-priming does occur for four-letter words if the prime and target are drawn from low-density neighbourhoods. For a partial-activation theory, an inhibitory mechanism that is sensitive to the number of prime-neighbours is required to explain the results. Of the several versions of a repetition account considered, the “best match” hypothesis appears to be the most promising: this assumes that priming is limited to the stimulus that best matches the prime. It is also shown that prime-target pairs that are related in form and meaning (e.g. made-MAKE) produce the same priming effect as identical pairs, as predicted by a repetition account that assumes a common entry underlying both forms.

What can we learn from the morphology of Hebrew? A masked-priming investigation of morphological representation.

All Hebrew words are composed of 2 interwoven morphemes: a triconsonantal root and a phonological word pattern. the lexical representations of these morphemic units were examined using masked priming. When primes and targets shared an identical word pattern, neither lexical decision nor naming of targets was facilitated. In contrast root primes facilitated both lexical decisions and naming of target words that were derived from these roots. This priming effect proved to be independent of meaning similarity because no priming effects were found when primes and targets were semantically but not morphologically related. These results suggest that Hebrew roots are lexical units whereas word patterns are not. A working model of lexical organization in Hebrew is offered on the basis of these results.

Translation priming with different scripts : Masked priming with cognates and noncognates in Hebrew-English bilinguals

Hebrew-English cognates (translations similar in meaning and form) and noncognates (translations similar in meaning only) were examined in masked translation priming. Enhanced priming for cognates was found with L1 (dominant language) primes, but unlike previous results, it was not found with L2 (nondominant language) primes. Priming was also obtained for noncognates, whereas previous studies showed unstable effects for such stimuli. The authors interpret the results in a dual-lexicon model by suggesting that (a) both orthographic and phonological overlap are needed to establish shared lexical entries for cognates (and hence also symmetric cognate priming), and (b) script differences facilitate rapid access by providing a cue to the lexical processor that directs access to the proper lexicon, thus producing stable noncognate priming. The asymmetrical cognate effect obtained with different scripts may be attributed to an overreliance on phonology in L2 reading.