Studies of lexical processing have relied heavily on adult ratings of word learning age or age of acquisition, which have been shown to be strongly predictive of processing speed. This study reports a set of objective norms derived in a large-scale study of British children's naming of 297 pictured objects (including 232 from the Snodgrass & Vanderwart, 1980, set). In addition, data were obtained on measures of rated age of acquisition, rated frequency, imageability, object familiarity, picture-name agreement, and name agreement. We discuss the relationship between the objective measure and adult ratings of word learning age. Objective measures should be used when available, but where not, our data suggest that adult ratings provide a reliable and valid measure of real word learning age.

Six experiments are reported that contrasted the effects of frequency and age of acquisition on written word recognition. Age of acquisition affected word-naming speed when frequency was controlled (Experiment 1), but there was no effect of frequency when age of acquisition was controlled (Experiment 2). Experiments 3 and 4 found an effect of age of acquisition upon immediate but not delayed naming speed, but no frequency effect on either immediate or delayed naming once age of acquisition was controlled. Independent effects of frequency and age of acquisition were observed in the lexical decision task (Experiments 5 and 6). Implications for theoretical accounts of word recognition and the possible roles of age of acquisition and frequency in word recognition are discussed.The frequency with which a word occurs in the language is widely believed to affect the ease which that word can be recognized and responded to, with common, high-frequency words being recognized more rapidly and/or more accurately than less common, low-frequency words. This belief has been incorporated into cognitive models of word recognition which regard the capacity to explain frequency effects as an important aspect of a model's adequacy (see Monsell, 1991, for a review of both evidence and theories). We argue in this article that for several aspects of visual word recognition, this belief in the importance of word frequency is mistaken. We suggest that it has arisen because^f a consistent failure to disconfound the possible effects of word frequency from effects of other factors which correlate with frequency, most notably the age at which words are learned. High-frequency words tend to be learned earlier in life than low-frequency words, so that sets of words selected as being of high or low frequency of occurrence tend also to be sets of words which are early-or late-acquired, respectively. Despite evidence that age of acquisition (AOA) affects visual word recognition (see Brown & Watson, 1987;Gilhooly & Watson, 1981), most studies of word frequency have failed to control for it. Evidence from the existing

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Previous research on the effects of age of acquisition on lexical processing has relied on adult estimates of the age at which children learn words. The authors report 2 experiments in which effects of age of acquisition on lexical retrieval are demonstrated using real age-of-acquisition norms. In Experiment 1, real age of acquisition emerged as a powerful predictor of adult object-naming speed. There were also significant effects of visual complexity, word frequency, and name agreement. Similar results were obtained in reanalyses of data from 2 other studies of object naming. In Experiment 2, real age of acquisition affected immediate but not delayed object-naming speed. The authors conclude that age-of-acquisition effects are real and suggest that age of acquisition influences the speed with which spoken word forms can be retrieved from the phonological lexicon.

Word frequency is widely believed to affect object naming speed, despite several studies in which it has been reported that frequency effects may be redundant upon age of acquisition. We report, first, a reanalysis of data from the study by Oldfield and Wingfield (1965), which is standardly cited as evidence for a word frequency effect in object naming; then we report two new experiments. The reanalysis of Oldfield and Wingfield shows that age of acquisition is the major determinant of naming speed, and that frequency plays no independent role when its correlation with other variables is taken into account. In Experiment 1, age of acquisition and phoneme length proved to be the primary determinants of object naming speed. Frequency, prototypicality, and imageability had no independent effect. In Experiment 2, subjects classified objects into two semantic categories (natural or man-made). Prototypicality and semantic category were the only variables to have a significant effect on reaction time, with no effect of age of acquisition, frequency, imageability, or word length. We conclude that age of acquisition, not word frequency, affects the retrieval and/or execution of object names, not the process of object recognition. The locus of this effect is discussed, along with the possibility that words learned in early childhood may be more resistant to the effects of brain injury in at least some adult aphasics than words learned somewhat later.Treatments of word retrieval in general, and object naming in particular, commonly propose that word frequency is an important determinant of the speed and accuracy of lexical access in speech production (e.g., Monsell, Doyle, & Haggard, 1989;. It is widely accepted that the less frequent a word is in the English language, the slower one will be to name a pictorial representation of the object. The standard reference given in support of this assertion is Oldfield and Wingfield (1965), who reported an experiment in which 12 subjects named 26 line drawings of different objects. Oldfield and Wingfield found an inverse relationship between naming latency and frequency, such that the lower the frequency of a particular item (i.e., the less common its occurrence in English), the longer it took to name it. There are a number of reasons to be cautious about accepting the results of that study.First, Oldfield and Wingfield (1965) failed to consider variables that correlate highly with frequency, such as length, imageability, and the age at which a word is acquired (age of acquisition). Second, they used the Thorndike-Lorge (1944) frequency count. This is an American word count drawn from school books and other similar reading material, and it may not have been a good index of the true frequency of word use by Oldfield and Wingfield's subjects (9 of the 12 of whom were under-