Novel word processing.

People who text messages often shorten words by eliminating internal letters (e.g., "climate, clmte"). Although these novel representations (i.e., subset word forms) are not true words, sentence context may prime semantic activation. We hypothesized that if participants are presented with a context sentence prime containing a subset form target word, then participants' performance should improve when the stimulus is presented to the left visual field/right hemisphere (LVF/RH) because the RH is less reliant on correct orthography than the left hemisphere (LH). We also hypothesized that participants' bias of processing novel stimuli is a function of visual field and hemisphere presentation. The results supported the hypothesis. When participants were shown subset word forms in the LVF/RH, their accuracy was significantly greater than when they were shown in the RVF/LH. Additionally, signal detection theory was applied to the results and substantiated the findings that participants' bias toward processing subset and orthographically correct words is a function of visual field and hemisphere presentation.

Knowledge-based inferences across the hemispheres: domain makes a difference.

Language comprehension occurs when the left-hemisphere (LH) and the right-hemisphere (RH) share information derived from discourse [Beeman, M. J., Bowden, E. M., & Gernsbacher, M. A. (2000). Right and left hemisphere cooperation for drawing predictive and coherence inferences during normal story comprehension. Brain and Language, 71, 310-336]. This study investigates the role of knowledge domain across hemispheres, hypothesizing that the RH demonstrates inference processes for planning knowledge while the LH demonstrates inference processes for knowledge of physical cause and effect. In experiment 1, sixty-eight participants completed divided-visual-field reading tasks with 2-sentence stimuli that relied on these knowledge areas. Results showed that readers made more planning inferences from the RH and more physical inferences from the LH, indicating inference processes occur from each hemisphere dependent upon the knowledge domain required to support it. In experiment 2, sixty-four participants completed the same reading task with longer, story-length stimuli to demonstrate the effect in a more realistic setting. Experiment 2 results replicated the findings from experiment 1, extending previous findings, specifying that hemispheric differences for inferences rely on knowledge domains.

Exploring cerebral asymmetries for the verb generation task.

This study investigated potential right hemisphere involvement in the verb generation task. Six divided visual field experiments explored cerebral asymmetries for word retrieval in the verb generation task as well as in rhyme generation and immediate and delayed word pronunciation. The typical right visual field/left hemisphere (RVF/LH) advantage was observed for pronunciation and rhyme generation. For verb generation, the RVF/LH advantage was obtained only when stimulus items had a single prepotent response and not when there were multiple response alternatives. A semantic priming experiment suggested that activation for less common, related verbs was maintained for a longer time course within the right than within the left hemisphere. The authors suggest that the right hemisphere may play a role in continued activation of semantically related response alternatives in word generation and discuss methodological implications of their findings.

Inference vs control sentences: are readers able to detect our intended differences?

The reliance of comprehension processes on knowledge to form explanatory inferences has been well established (Grasser, Singer, & Trabasso, 1994), yet the evidence that supports these studies is derived from sentence pairs that are largely unexamined. While some recent studies have suggested that the stimulus sentences utilized in comprehension research need further specification (Shears & Chiarello, 2004), there has been little 'normal reading' data provided that examines what readers are able to detect from traditional inference-requiring vs control sentence pairs. The current study utilized stimuli sentences that have historically been used to support inference research (Singer, 1995) as well as some newly developed sentences, to examine whether readers detect differences between control vs inference conditions, and to further examine whether readers could discern when inference sentences achieved an outcome or goal vs when these sentences did not achieve an outcome or goal.

Influence of word class proportion on cerebral asymmetries for high- and low-imagery words.

It has been claimed that the typical RVF/LH advantage for word recognition is reduced or eliminated for imageable, as compared to nonimageable, nouns. To determine whether such word-class effects vary depending on the stimulus list context in which the words are presented, we varied the proportion of high- and low-image words presented in a lateralized lexical decision task (0, 25, 50, 75, or 100% high image). Although the RVF/LH advantage for high-image words was unaltered by word-class proportion, a significant linear trend was obtained for the low-image words such that the RVF/LH advantage increased as the proportion of low-image words increased. We discuss the implications of these findings for models of how lexical processing is distributed across hemispheres.

Priming of strong semantic relations in the left and right visual fields: a time-course investigation.

Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical associates such as arm-leg) were employed in a low relatedness proportion lexical decision priming paradigm. A range of prime-target stimulus onset asynchronies (SOAs: 150-800 ms) was included. Only very weak evidence was obtained for a LVF priming lag at the briefest SOA, while priming was bilateral at moderately long SOAs. We consider these data in the context of previous time-course studies and suggest that, when highly semantically similar word pairs are used, a right hemisphere priming lag is, at best, a very small effect.

No go on neutrals? An interhemispheric account of semantic category priming.

In a divided-visual-field priming paradigm, participants made manual lexical decisions performing either go no-go responses, or yes-no responses, to related prime-target word pairs that were nonassociated, category members (DEER-PONY). Half of each response group received unrelated (ATTIC-PONY) baselines and half received neutral (BLANK-PONY) baselines. In the go no-go response, small but reliable priming was obtained in both target visual fields and there was a reliable slowing of response time in the right visual field/left hemisphere for participants receiving the neutral baseline. In the yes-no response, greater priming was obtained from a neutral baseline, as compared to an unrelated baseline. We show that under appropriate conditions priming for these stimuli occurs in both visual fields. We also report that cross-visual-field advantages emerged as cognitive task load increased across combinations of baseline and response variables. We conclude that task load may be as important a factor in priming asymmetries as SOA or type of semantic relationship.

Differential asymmetries for recognizing nouns and verbs: where are they?

To support categorical representation in the brain for grammatical class, it is necessary to show that noun-verb differences are attributable to parts of speech and not to covarying semantic factors. Prior visual-half field investigations of noun-verb processing have confounded grammatical class with imageability. The current study included numerous tests of differential noun-verb processing across visual fields for stimuli equated for imageability. Task (lexical decision, pronunciation) and list context (blocked vs. mixed lists) variables were examined in 168 right-handed participants. There was no reliable reduction of the right visual field advantage for moderately imageable nouns as compared with verbs. If there are qualitative hemisphere differences in single-word noun and verb recognition, these may be attributable to semantic dimensions that tend to covary with grammatical class.