The divided visual world paradigm: Eye tracking reveals hemispheric asymmetries in lexical ambiguity resolution

Abstract

Eye tracking was combined with the visual half-field procedure to examine hemispheric asymmetries in meaning selection and revision. In two experiments, gaze was monitored as participants searched a four-word array for a target that was semantically related to a lateralized ambiguous or unambiguous prime. Primes were preceded by a related or unrelated centrally-presented context word. In Experiment 1, unambiguous primes were paired with concordant weakly-related context words and strongly-related targets that were similar in associative strength to discordant subordinate-related context words and dominant-related targets in the ambiguous condition. Context words and targets were reversed in Experiment 2. A parallel study involved the measurement of event-related potentials (ERPs; Meyer, A. M., and Federmeier, K. D., 2007. The effects of context, meaning frequency, and associative strength on semantic selection: Distinct contributions from each cerebral hemisphere. Brain Res. 1183, 91-108). Similar to the ERP findings, gaze revealed context effects for both visual fields/hemispheres when subordinate-related targets were presented: initial gaze revealed meaning activation when an unrelated context was utilized, whereas later gaze also revealed activation in the discordant context, indicating that meaning revision had occurred. However, eye tracking and ERP measures diverged when dominant-related targets were presented: for both visual fields/hemispheres, initial gaze indicated the presence of meaning activation in the discordant context, and, for the right hemisphere, discordant context information actually facilitated gaze relative to unrelated context information. These findings are discussed with respect to the activeness of the task and hemispheric asymmetries in the flexible use of context information. KeywordsLexical Ambiguity; Cerebral Hemispheres; Context Effect; Eye Tracking Most English words are ambiguous (Rodd, Gaskell, and Marslen-Wilson, 2004), having either multiple unrelated meanings (homonymy) or multiple related senses (polysemy). For example, the homonym bank can refer to a financial institution or the edge of a river, and the polysemous word lamb can refer to food or a living animal. Lexical ambiguity has been the subject of much research over the past several decades; many studies (e.g., Duffy et al., 1988;Simpson, Corresponding Author: Aaron M. Meyer, Beckman Institute, University of Illinois, 405 N. Mathews Ave., Urbana, IL 61801, meyeram@uiuc.edu, (217) 244-9638. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1981;Swinney and Hakes, 1976;Ta...

Event-related potentials reveal the effects of aging on meaning selection and revision

“…In contrast, the RH has been associated with a more flexible use of context (e.g., Bowden, Jung-Beeman, Fleck, & Kounios, 2005; Coulson and Williams, 2005; Meyer and Federmeier, 2008), and this flexibility could facilitate the generation of words that are unrelated to the expected sentence completion. Strikingly, higher functioning older adults – specifically, those with better inhibition and higher working memory spans – were more likely to show asymmetrical priming for subordinate associates.…”

Automatic and controlled aspects of lexical associative processing in the two cerebral hemispheres

“…For instance, prior work with behavioral and ERP measures revealed no evidence for hemispheric differences in the automatic activation of multiple, divergent meanings of words (Kandhadai & Federmeier, 2007, 2008) and even evidence for LH dominance in processing the secondary sense of words with multiple meanings (Meyer & Federmeier, 2007). However, measures of more effortful semantic analysis have found some data suggesting that meaning selection may be more focal in the LH (Meyer & Federmeier, 2008). …”

Context modulates hemispheric asymmetries in the resolution of lexical ambiguity

“…In general, the concept of mandatory interhemispheric collaboration that we offer is in line with Federmeier's ideas (Federmeier & Kutas, 1999;Lee & Federmeier, 2006;Meyer & Federmeier, 2008). Federmeier's data strongly suggest that normal language comprehension emerges from the joint operation of multiple mechanisms, arising not only from activity in classic left hemisphere language areas, but from a broader, bilateral network encompassing processes at several levels (e.g.…”

“…A complete understanding of the cognitive and neural mechanisms underlying normal language comprehension will require a further specification of not only the individual, but also the interactive contributions of each cerebral hemisphere. Current methods employing divided visual fields and brain imaging, including ERP (Meyer & Federmeier, 2008) and fMRI (Whitney et al, 2009) have attempted to characterise separate, dynamic networks that process lexical ambiguity, but the data from the two modalities is not yet integrated into one coherent model. Furthermore, the inability of both research methods to support causal models means the findings are restricted in scope.…”

“…In divided visual field studies it might be misleading to ignore responding hand effects since a visual fieldÁhand interaction is expected under some experimental conditions due to transfer time between the hemisphere that receives the stimulus and the hemisphere that generates the response (Marzi, Bisiacchi, & Nicoletti, 1991). Some EEG studies of lexical ambiguity have counterbalanced the responding hand (Federmeier & Kutas, 1999;Lee & Federmeier, 2006;Meyer & Federmeier, 2008). These studies generally support the claim that the LH is focused on the salient, or in their theoretical framework, on the predicted meaning while the RH integrates the perceived target with previously presented information, allowing less predicted targets such as subordinate meanings of ambiguous words to be judged correctly as relevant.…”