DMDX is a Win32 program designed to precisely time the presentation of text, audio, graphical, and video material and to enable the measurement of reaction times (RTs) to these displays with millisecond accuracy. It represents an extension of a suite of DOS-based programs known as DMASTR, developed and tested at Monash University in Australia over a period of 15 years, starting in 1975, by a team includingthe first author, Rod Dickinson, Wayne Murray, and Mike Durham. Graphics and sound capabilities were added in 1989 by Jonathan Forster, and the extension to a Windows 9x platform was carried out by Jonathan Forster at the University of Arizona in 1997.The purpose of the present article is (1) to inform the research community about the existence of the software and its capabilities, (2) to provide a nontechnical explanation of how the software works, and (3) to answer the skepticism expressed in some quarters about the possibility of using the Windows operating system in a real-time environment (see, e.g., Myors, 1999).First, a brief historical note. The DMASTR suite was originally developed by the first author in 1975 for a PDP-11 computer running under RT-11. It was written in assembler code (MACRO) and was an interrupt-driven program that synchronized the activity of the display program with the position of the raster in the display monitor, thereby enabling accurate measurement of the time interval between when the display actually appeared and when the subject responded to that display. The RT-11 operating system gave the programmer total control over all the operations of the computer, so that the programmer knew precisely when each display event occurred and when each response was made by the subject. With the advent of far cheaper IBM-compatible PCs, the switch was made in 1983 to a DOS-based program (DM) written in C with no loss of control over timing. This version of DMASTR was still purely text based. In 1989, the second author extended the system to include graphical displays and sound, using the Borland Turbographics C library. However, this program (DMTG) was restricted to a particular graphics format (not widely supported), a particular speech-editing system (BLISS, developed by J. Mertus at Brown University), and as a consequence, it was also limited to a narrow range of sound cards for which BLISS drivers had been written.As MacInnes and Taylor (2001) point out, attempting to stay with DOS means that researchers are restricted to outdated hardware and software, a problem that becomes more acute with each passing year. As the supply of sound cards suitable for DMTG began to dwindle (suppliers going out of business or completely changing the design of the card), it became clear that any new application having a life span of more than a year or two would have to be based on the de facto Windows standard. The idea was that if a piece of hardware worked with Windows, it would also work with DMASTR. In that way, we could keep abreast of new technologywithout having to write new device drivers for eve...

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 classification for words that are presented more than once during the experiment, even though considerable time may have elapsed between successive presentations (Forbach, Stanners, & Hochhaus, 1974;Kirsner & Smith, 1974; Scarborough, Cortese, & Scarborough, 1977). This phenomenon is referred to as the repetition effect.There are basically two different approaches to the repetition effect. On the one hand, it is seen as the product of a temporary modification to the process of lexical access (e.g., Forbach et al., 1974). As a result of recent activation, the lexical representation of a word is left in a state of increased accessibility. This priming effect can then be used as a powerful diagnostic tool for analyzing the

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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.

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 Morton's 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.

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.

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.