One could easily argue that the most commonly studied stimulus set in experimental psychology involves English words. The study of the memory and reading of words has been central to research since Cattell (1886). Words are well-described units that provide the link between perception and meaning, and so have been critical to developments in computational modeling (e.g., McClelland & Rumelhart, 1981), neuroimaging (e.g., Petersen, Fox, Posner, Mintun, & Raichle, 1989, and conceptions of attention and automaticity (e.g., Neely, 1977;Stroop, 1935), among many other research areas.Given the importance of words as a stimulus set, one might assume that there are relatively straightforward ways to study lexical processing, and that there is a wellconstrained set of findings to which one can appeal in building models of word processing. Although there has been considerable progress in understanding how people process words, there are some clear gaps in the available literature. This paper describes the English Lexicon Project (ELP), which provides a behavioral database for over 40,000 words and nonwords that will help fill some of these gaps. The present description will focus on visual word recognition, although, as described below, the current database has relevance for other aspects of word processing, such as memory and speech production. Before describing the ELP, we will briefly describe the behavioral measures in the database, the limitations in our current knowledge, and how this database will help address these limitations. LEXICAL DECISIONS AND NAMING AS THE BEHAVIORAL TARGETSAlthough there are multiple ways to measure lexical processing (e.g., eye-fixation data, probability of iden- The English Lexicon Project is a multiuniversity effort to provide a standardized behavioral and descriptive data set for 40,481 words and 40,481 nonwords. It is available via the Internet at elexicon.wustl.edu. Data from 816 participants across six universities were collected in a lexical decision task (approximately 3400 responses per participant), and data from 444 participants were collected in a speeded naming task (approximately 2500 responses per participant). The present paper describes the motivation for this project, the methods used to collect the data, and the search engine that affords access to the behavioral measures and descriptive lexical statistics for these stimuli.

Speeded visual word naming and lexical decision performance are reported for 2428 words for young adults and healthy older adults. Hierarchical regression techniques were used to investigate the unique predictive variance of phonological features in the onsets, lexical variables (e.g., measures of consistency, frequency, familiarity, neighborhood size, and length), and semantic variables (e.g. imageahility and semantic connectivity). The influence of most variables was highly task dependent, with the results shedding light on recent empirical controversies in the available word recognition literature. Semantic-level variables accounted for unique variance in both speeded naming and lexical decision performance, level with the latter task producing the largest semantic-level effects. Discussion focuses on the utility of large-scale regression studies in providing a complementary approach to the standard factorial designs to investigate visual word recognition.

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Age of acquisition (AoA) ratings were obtained and were used in hierarchical regression analyses to predict naming and lexical-decision performance for 2,342 words (from Balota, Cortese, Sergent-Marshall, Spieler, & Yap, 2004). In the analyses, AoA was included in addition to the set of predictors used by Balota et al. (2004). AoA significantly predicted latency performance on both tasks above and beyond the standard predictor set. However, AoA was more strongly related to lexical-decision performance than to naming performance. Finally, the previously reported effect of imageability on naming latencies by Balota et al. was not significant with AoA included as a factor. These results are consistent with the idea either that AoA has a semantic/lexical locus or that AoA effects emerge primarily in situations in which the input-output mapping is arbitrary.

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