Attention effects on motion processing are larger in the left vs. the right visual field

What do lateralized displays tell us about visual word perception? A cautionary indication from the word-letter effect

The neural basis of the right visual field advantage in reading: An MEG analysis using virtual electrodes

In recognition of the ecological importance of processing the talking face and its potential role in the development of right hemisphere specialization for face processing, descriptive studies examined the effects of concurrent speech on hemispheric lateralization for face recognition. To explore the potentially special nature of the face-speech concurrence, the effect of speech on inverted face recognition was also examined. Separate groups of right-handed participants took part in each of 4 studies. In Study 1, participants were asked to identify which of 4 male faces was presented in tachistoscopic fashion via computer. Correct recognition of faces was significantly faster in the left visual field (LVF) than in the right visual field (RVF), and the majority of participants exhibited a LVF processing-speed advantage (ADV). However, those participants whose responses to faces were faster in the RVF (RVF ADV) were more accurate at recognizing faces. In Study 2, a spoken word was incidentally presented simultaneously with each face. This altered hemispheric lateralization for face recognition. There was no longer evidence for LVF responses being faster than RVF ones or for participants with a RVF ADV being better at recognizing faces. However, these participants were superior at an unannounced speech recognition test. Unexpectedly, concurrent processing did not diminish performance on face recognition. Good memory for the incidental speech was also evident during an unannounced speech recognition test, indicating that participants successfully did 2 things at once. It was hypothesized that the special nature of the face-speech combination was responsible for this. Concurrent processing of the nonecological combination of inverted faces and speech provided no evidence in support of this hypothesis.

A partial report procedure and a backward masking paradigm were employed to explore lateral asymmetries in components of letter recognition. Stimulus displays were displaced off-centre into the left visual field (LVF) or the right visual field (RVF). Visual field differences in the effect of a delayed backward mask indicated an RVF superiority in the rate of read-out or encoding. Comparison of masked and unmasked full report also yielded estimates of iconic persistence. The persistence of these peripheral displays was surprisingly brief, although it was significantly longer in the LVF (57 ms) than in the RVF (34 ms). Precueing by colour and by location produced a larger partial report advantage in the RVF, reflecting a superiority in selective sampling. With postcueing no partial report effect was obtained at any delay, and this failure was attributed to the briefness of the iconic persistence.

Face gender categorization and hemispheric asymmetries: Contrasting evidence from connected and disconnected brains

Directional biases in visual perception were examined for individual differences in sixty-five subjects on two tasks. One task required judgments of the onset asynchrony of pairs of dots presented at random, either one dot in each visual field, or both in the left visual field (LVF), or the right visual field (RVF). The second task required the recall of four letter strings presented randomly in either visual field. Dot-asynchrony judgments were influenced by two main biases: first, an outward from the centre bias in both visual fields, and second, a lateral bias which was significantly from left to right (L-R) in the total sample. A substantial minority of subjects were biased to judge the dots as occurring in right to left (R-L) order. Accuracy of letter report decreased fairly consistently from L-R in the RVF but varied in the LVF. Some subjects showed a L-R report gradient, some a R-L gradient, and some a U-shaped recall pattern. Significant correlations between measures of L-R and R-L biases on the two tasks show that the biases have some stable foundation. The findings suggest that there are directional biases affecting visual perception which are due neither to learned reading habits, nor to cerebral specialization of function.

Visual field asymmetries in attention vary with self-reported attention deficits

T151. Visuospatial processing load enhance the brain activity associated with motor preparation

Interhemispheric cooperation and non-cooperation during word recognition: Evidence for callosal transfer dysfunction in dyslexic adults

Observers are faster to detect a target among a set of distracters if the targets and distracters come from different color categories. This cross-boundary advantage seems to be limited to the right visual field, which is consistent with the dominance of the left hemisphere for language processing [Gilbert et al., Proc. Natl. Acad. Sci. USA 103, 489 (2006)]. Here we study whether a similar visual field advantage is found in the color identification task in speakers of Mandarin, a language that uses a logographic system. Forty late Mandarin-English bilinguals performed a blue-green color categorization task, in a blocked design, in their first language (L1: Mandarin) or second language (L2: English). Eleven color singletons ranging from blue to green were presented for 160 ms, randomly in the left visual field (LVF) or right visual field (RVF). Color boundary and reaction times (RTs) at the color boundary were estimated in L1 and L2, for both visual fields. We found that the color boundary did not differ between the languages; RTs at the color boundary, however, were on average more than 100 ms shorter in the English compared to the Mandarin sessions, but only when the stimuli were presented in the RVF. The finding may be explained by the script nature of the two languages: Mandarin logographic characters are analyzed visuospatially in the right hemisphere, which conceivably facilitates identification of color presented to the LVF.

ABSTRACTIn lateralized lexical decision tasks (LDTs), accuracy is higher and reaction times (RTs) are faster for right visual field (RVF) than left visual field (LVF) presentations. Visual field differences are thought to demonstrate the left hemisphere's (LH) dominance for language. The use of different tasks and words between studies and languages make direct comparisons difficult. We performed a lateralized LDT for which we selected four to six letter words that are used in three languages of Switzerland (French, German, and Italian) and English and Dutch. We accounted for the potential moderating roles of sex, handedness and multilingualism (early acquisition versus late acquisition of at least one second language). One hundred participants were tested at a French-speaking University in Switzerland. All performed a French vocabulary knowledge task [Brysbaert (2013). Lextale_FR a fast, free, and efficient test to measure language proficiency in French. Psychologica Belgica, 53(1), 23–27. Retrieved from http://hdl.handle.net/1854/LU-4373981]. Results showed a RVF over LVF advantage (accuracy, RTs and signal detection theory measures) for all groups, that is, irrespective of participants’ sex, handedness and how many languages they spoke. We observed, however, that enhanced vocabulary knowledge related to a right hemisphere shift in early bilinguals and a LH shift in late bilinguals. We discuss how the current observations can inform future studies suitable for the validation of the current task using an “international” vocabulary.

Cross-language tests of hemispheric strategies in reading nonwords.

Lateralization of attention in adults with ADHD: Evidence of pseudoneglect

The patterns of activation invoked in the two cerebral hemispheres by written words may be different. Two lexical decision experiments investigated several aspects of such activation patterns. Experiment 1 tested phonological and orthographic priming in the hemispheres, manipulating two levels of phonological and two levels of orthographic similarity. Orthographic priming in the left visual field (LVF) was significantly larger than in the right visual field (RVF). In Experiment 2, primes were phonologically identical to the targets (homophones) but differed in their orthographic similarity. For LVF targets, only orthographic priming was significant, whereas for RVF targets, the phonological primes were effective regardless of their orthographic similarity. The results imply that orthographic activation, though maintained by both hemispheres, is more characteristic of right hemisphere word recognition processes, whereas phonological priming is more characteristic of left hemisphere processes.

The right and left visual fields each project to the contralateral cerebral hemispheres. The current study aimed to investigate the extent of the functional overlap of the two hemifields along the vertical meridian. We applied repetitive transcranial magnetic stimulation (rTMS) over the left and right occipital cortex to investigate whether the foveal representation of words is bilaterally represented or is split between the two hemispheres. Employing a lateralized lexical decision task, we first showed a double dissociation between the stimulated cortical site and performance; right visual field (RVF) but not left visual field (LVF) performance was impaired when the left visual cortex was stimulated, and LVF but not RVF performance was impairred when the right visual cortex was stimulated. Unilateral stimulation also significantly impaired lexical decision latencies to centrally presented words. These findings support the suggestion that foveal representation of words is split. We discuss future strategies for the use of TMS in further tests of the split representation account.