Orthographic neighborhood effects during lateralized lexical decision are abolished with bilateral presentation.

Abstract

Words presented to the right visual field (RVF) are processed more rapidly than those in the left visual field (LVF), presumably because of more direct links to the language dominant left cerebral hemisphere. This effect is moderated by a word's orthographic neighborhood size (N), with LVF facilitation and RVF inhibition for words with a large N. Across two experiments, we sought to further examine lateralized N effects. Experiment 1 examined how hemispheric dominance for language influenced lateralized N effects, in 140 left-handers using a visual half-field task with bilateral presentation. Neither participants with a right ear advantage on a dichotic listening task nor participants with no right ear advantage showed the expected N effect, making the results ambiguous: it could be that left-handers fail to show N effects, or the effect could be abolished by some procedural aspect. Experiment 2 looked to test these options by testing 56 right-handers who responded to the same stimulus set under the original bilateral presentation condition and under unilateral presentation. N effects were found under unilateral but not bilateral presentation. We had adopted bilateral presentation because it had been recommended as better than unilateral presentation for controlling fixation and visual stimulation; our results indicate that this is not a minor methodological modification: it can dramatically affect lateralized N effects. Public Significance StatementWords presented in the right visual field are initially projected to the left cerebral hemisphere. Conversely, words presented in the left visual field are initially projected to the right hemisphere. Word-level properties, such as orthographic neighborhood size, differentially affect word identification across each cerebral hemisphere. In particular, having many neighbors facilities word identification in the right hemisphere whereas it inhibits word identification in the left hemisphere. We explored these asymmetries further across two studies where words were displayed in isolation or accompanied by a distractor. The data is conclusive in showing that presentation mode has nontrivial consequences for lateralized orthographic neighborhood effects: neighborhood effects are only detectable under unilateral presentation where words are displayed in isolation

Lexical processing across the visual field.

“…First, the experiments were conducted entirely online, limiting experimental control over participants’ viewing conditions, hardware, operating system, or browser, which all can potentially affect timing performance. However, recent studies have demonstrated comparable performance in online and laboratory studies of lateralized word processing (Mills et al, 2022; Parker et al, 2021; Veldre et al, 2022) and masked priming (Angele et al, 2022), suggesting that online data collection is suitable for paradigms requiring precise timing.…”

Opposite perceptual biases in analogous auditory and visual tasks are unique to consonant-vowel strings and are unlikely a consequence of repetition

“…The use of bilateral presentation had several advantages in the context of the current experiment compared to unilateral presentation: (1) it enabled direct comparison with Oltedal and Hugdahl (2017) who also employed bilateral presentation for the visual presentation of consonant-vowel strings; (2) its adoption allows a more direct parallel (compared to unilateral visual presentation) between the visual and the auditory modality, as bilateral visual presentation elicits competition between LVF and RVF (Hunter & Brysbaert, 2008;Hausmann et al, 2019); (3) it followed from Hunter and Brysbaert's (2008) observation that divided visual field reading effects are larger and more stable when bilateral presentation is adopted instead of unilateral presentation (Boles, 1987(Boles, , 1990(Boles, , 1994; see also Iacoboni & Zaidel, 1996; for more recent applications of this technique, see Willemin et al, 2016, Hausmann et al, 2019, and Mills et al, 2022; and (4) in the absence of explicit fixation control via eye tracking, the use of bilateral presentation can (by virtue of competition for attentional resources) reduce the probability of eye movements (Hunter & Brysbaert, 2008).…”

“…While the corpus callosum does allow for the transfer of information between the hemispheres, there is more efficient processing for linguistic stimuli arriving at the left hemisphere as there is an absence of transfer/processing costs from the non-dominant to the language dominant hemisphere (Bonandrini, Paulesu et al, 2023;Bourne, 2006;Hellige, 1993;Hunter & Brysbaert, 2008). It is not surprising then that many studies have produced a strong RVF advantage for the processing of written words (e.g., Bonandrini, Paulesu et al, 2023;Brederoo et al, 2019Brederoo et al, , 2020Hausmann et al, 2019;Mills et al, 2022;Parker et al, 2020;Perea et al, 2008;Willemin et al, 2016) despite using very different stimuli between studies.…”