Although many models of word recognition have postulated loci for the simple effects of Context, Stimulus Quality, and Word Frequency, most of them are problematic in that they do not account for the pattern of joint effects among these factors. The experiments reported here show that, among other things, Word Frequency interacts with Context but is additive with Stimulus Quality in the context of a lexical decision experiment that also produces an interaction between Stimulus Quality and Context. The pattern of joint effects among these factors is accommodated by a multistage activation model that is based on the framework proposed by Besner and Smith (1992a).

The influence of semantic ambiguity on word identification processes was explored in a series of word naming and lexical-decision experiments. There was no reliable ambiguity effect in 2 naming experiments, although an ambiguity advantage in lexical decision was obtained when orthographically legal nonwords were used. No ambiguity effect was found in iexical decision when orthographically illegal nonwords were used, implying a semantic locus for the ambiguity advantage. These results were simulated by using a distributed memory model that also produces the ambiguity disadvantage in gaze duration that has been obtained with a reading comprehension task. Ambiguity effects in the model arise from the model's attempt to activate multiple meanings of an ambiguous word in response to presentation of that word's orthographic pattern. Reasons for discrepancies in empirical results and implications for distributed memory models are considered.Any comprehensive theory of mental representation and process must accommodate the complex means by which concepts are communicated through language. Through the course of history, humans have developed tools of communication that facilitate the relaying of ideas and concepts, such as a writing system or orthography. This mapping of concepts to orthography is not entirely one to one, however, resulting in some words that correspond to multiple concepts, which are known as semantically ambiguous words. When reading text, the context provided by preceding words and sentences provides a means of disambiguating such words. As a result, we may not even notice the ambiguity in words that we are reading in context. If, on the other hand, semantically ambiguous words are presented in isolation, their alternative meanings are readily accessible, and thus their ambiguous nature is noticed. In the research reported in this article, we compare performance on semantically ambiguous words with that of semantically unambiguous words in isolated word identification tasks and describe simulations of the empirical effects within the framework of a distributed memory architecture (Masson, 1995).The effect of semantic ambiguity on isolated word identification has usually been determined by comparing performance on unambiguous words (which are associated with only one Ron Borowsky and Michael E. J. Masson, Department of Psychology, University of Victoria, British Columbia, Canada.This research was supported by the Natural Sciences and Engineering Research Council of Canada. We thank Steve Lindsay for use of his equipment. We are grateful to Derek Besner and Paul Fera for suggesting that neighborhood density be examined in these experiments and to Rick Bourassa for suggesting the delayed naming experiment.Correspondence concerning this article should be addressed to Ron Borowsky, who is now at the Department of Psychology, 9 Campus Drive, University of Saskatchewan, Saskatoon, Saskatchewan, Canada STN 5A5, or to Michael E. J. Masson, Department of Psychology, University of Victoria, P.O. Box 3050, Victor...

Cross-education of strength is the increase in strength of the untrained contralateral limb after unilateral training of the opposite homologous limb. We investigated central and peripheral neural adaptations associated with cross-education of strength. Twenty-three right-handed females were randomized into a unilateral training group or an imagery group. A sub-sample of eight subjects (four training, four imagery) was assessed with functional magnetic resonance imaging (fMRI) for patterns of cortical activation during exercise. Strength training was 6 weeks of maximal isometric ulnar deviation of the right arm, four times per week. Peak torque, muscle thickness (ultrasound), agonist-antagonist electromyography (EMG), and fMRI were assessed before and after training. Strength training was highly effective for increasing strength in trained (45.3%; P < 0.01) and untrained (47.1%; P < 0.01) limbs. The imagery group showed no increase in strength for either arm. Muscle thickness increased only in the trained arm of the training group (8.4%; P < 0.001). After training, there was an enlarged region of activation in contralateral sensorimotor cortex and left temporal lobe during muscle contractions with the untrained left arm (P < 0.001). Training was associated with a significantly greater change in agonist muscle EMG pooled over both limbs, compared to the imagery group (P < 0.05). These results suggest that cross-education of strength may be partly controlled by adaptations within sensorimotor cortex, consistent with previous studies of motor learning. However, this research demonstrates the involvement of temporal lobe regions that subserve semantic memory for movement, which has not been previously studied in this context. We argue that temporal lobe regions might play a significant role in the cross-education of strength.

Most current models of the neurophysiology of basic reading processes agree on a system involving two cortical streams: a ventral stream (occipital-temporal) used when accessing familiar words encoded in lexical memory, and a dorsal stream (occipital-parietal-frontal) used when phonetically decoding words (i.e., mapping sublexical spelling onto sounds). The models diverge, however, on the issue of whether the insular cortex is involved. The present fMRI study required participants to read aloud exception words (e.g., 'one', which must be read via lexical memory) and pseudohomophones (e.g., 'wun', which must be read via sublexical spelling to sound translation) to examine the processing streams as well as the insular cortex, and their relationship to lexical and sublexical reading processes. The present study supports the notion of independent ventral-lexical and dorsal-sublexical streams, and further suggests the insular cortex to be sensitive to phonological processing (particularly sublexical spelling-sound translation). These latter findings illuminate the nature of insular activity during reading, which must be explored further in future studies, and accounted for in models of the neurophysiology of reading.

Single-word semantic context and stimulus degradation yield an overadditive interaction during word recognition for readers of alphabetic English (a deep orthography in which lexical access relies primarily upon orthographic information). Lukatela and Turvey reported that this overadditive interaction is absent when subjects read a shallow orthography like Serbo-Croatian. They argued that this arises because subjects rely upon a prelexical phonological code for lexical access. The present experiment on the reading of alphabetic English suggests that Lukatela and Turvey's results are due to their choice of a baseline against which priming is assessed. Some implications for models of word recognition are noted. This research was supported by Natural Sciences and Engineering Research Council of Canada Grant A0988 to Derek Besner. We thank L. Katz, C. Perfetti, and particularly A. Pollatsek for their comments on a previous version of this article. Thanks also to Keith McGowan for programming assistance and Eyal Reingold for trenchant comments.