Right Visual Field Research Articles

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

ABSTRACT Despite wide reporting of a right ear (RE) advantage on dichotic listening tasks and a right visual field (RVF) advantage on visual half-field tasks, we know very little about the relationship between these perceptual biases. Previous studies that have investigated perceptual asymmetries for analogous auditory and visual consonant–vowel tasks have indicated a serendipitous finding: a RE advantage and a left visual field (LVF) advantage with poor cross-modal correlations. In this study, we examined the possibility that this LVF advantage for visual processing of consonant–vowel strings may be a consequence of repetition by examining perceptual biases in analogous auditory and visual tasks for both consonant–vowel strings and words. We replicated opposite perceptual biases for consonant–vowel strings (RE and LVF advantages). This did not extend to word stimuli where we found RE and RVF advantages. Furthermore, these perceptual biases did not differ across the three experimental blocks. Thus, we can firmly conclude that this LVF advantage is unique to consonant–vowel strings and is not a consequence of the repetition of a relatively limited number of stimuli. Finally, a test of covariances indicated no cross-modal relationships between laterality indices suggesting that perceptual biases are dissociable within individuals and cluster on mode of presentation.

Familiarity with words modulates interhemispheric interactions in visual word recognition.

Bilateral redundancy gain (BRG) indicates superior performance in bilaterally presented word recognition in the left and right visual fields (RVFs) relative to word recognition given in either the left or the RVF. The BRG may be modulated by participants’ subjective familiarity with words as previous studies found smaller regional activations in the brain as they become proficient. It can be assumed that visual recognition of words with high subjective familiarity indicates skilled performance in visual recognition. Thus, this study examined the subjective familiarity effect of visual words on the BRG during lateralized lexical decision performances. It showed that the significant BRG of response times was only observed in the most familiar word condition (F4 level); on the other hand, accuracy results revealed the significant BRGs in all the subjective familiarity levels (F1, F2, F3, and F4 levels). These results suggest that the bilateral presentation of identical words with higher subjective familiarity facilitates the recognition led by cooperative interactions between cerebral hemispheres. Therefore, the subjective familiarity with visual words modulates the efficiency of hemispheric interactions in visual word recognition.

The examination of the visual-perceptual locus in hemispheric laterality of the word length effect using Korean visual word

ABSTRACT Greater word length effects have been reported when a word was presented in the left visual field (LVF) than when presented in the right visual field (RVF). The current study employed 2 experiments to examine the visual-perceptual loci of asymmetric word length effect while testing the physical and linguistic length effects and the effect of visual angle increase at the RVF. Experiment 1 showed significant effects on the number of strokes in both VHFs (visual half fields) with the added significance of the number of syllables in the LVF, suggesting both parafoveal fields were affected by the physical length factors in contrast with the linguistic length factors, inducing asymmetric word length effects in the symmetrically presented word recognition in parafoveal vision. Experiment 2 widened the visual angle of the RVF presentation to test the differential effects of the visual-perceptual difficulty across the VHFs. It showed successful interruption at the RVF word recognition and comparable word length effects between the LVF and RVF. Therefore, this study suggests that the asymmetric word length effects in the parafoveal word recognition are attributable to the greater visual-perceptual difficulty at the LVF than at the RVF.

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

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. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Lateralization of Color Discrimination Performance and Lexical Effects in Patients With Chronic Schizophrenia.

Introduction: Patients with schizophrenia experience various visual disturbances. However, information regarding color perception in these patients is rare. In this study, we used a lateralized color search task to investigate whether difference in color name affects color recognition in patients with schizophrenia.Methods: In a color search task, we controlled the position of the target that emerged from the left visual field (LVF) or right visual field (RVF) as well as the color category. In this task, both the target and the distractors had the same or different color name (e.g., blue or green).Results: Patients with schizophrenia showed faster performance in the color search task with different color names for target-distractors when the target emerged from the LVF than when it emerged from the RVF. However, the same laterality was not observed in healthy controls. This finding indicates that semantic processing for color name differences influenced visual discrimination performance in patients with schizophrenia more profoundly in the LVF than in the RVF.Conclusion: This lateralized performance could imply the failure of the left hemisphere language processing dominance in schizophrenia. A search paradigm combining target position and category may indicate that automatic language processing depends on imbalanced hemispheric function in schizophrenia.

Brain lateralization of face recognition in hearing-impairedindividuals

<p indent=0mm>Adults show the left-visual field/right-hemisphere advantage for the recognition of face. The experience of auditory deprivation and sign language in hearing-impaired individuals could reshape the function and structure of brain. Previous studies suggest that hearing-impaired individuals demonstrate the right-visual field or left-hemisphere superiority for visuospatial attention, visual motion information processing and facial expression processing. The present study aims to further investigate the brain lateralization for face processing in hearing-impaired adults by using behavioral and ERP measures. In experiment 1, the divided visual field paradigm was used and the accuracies and corrected reaction times of face processing in the left-visual field were found to be significantly higher and shorter than those in the right-visual field for hearing individuals, whereas there were no significant differences between left- and right-visual field in hearing-impaired individuals. However, both hearing and hearing-impaired individuals showed the same left-visual field superiority for word processing efficiency. In experiment 2, One-back task and ERPs were used to investigate the brain lateralization of face recognition in hearing and hearing-impaired individuals. The results showed that the N170 amplitude for face processing in the right hemisphere was significantly larger than that in the left hemisphere for hearing individuals. However, there was no significant difference in N170 amplitude between the left and right hemispheres for hearing-impaired individuals. As for word processing, hearing and hearing-impaired individuals both showed a bilateral activation. Therefore, the current study provided converging evidence that the left-visual field or right hemisphere superiority for face processing in hearing-impaired individuals disappeared. These findings not only expand our understanding of the face processing in hearing-impaired individuals, but also help us understand the hemispheric organization for face recognition.

Electrophysiological Correlates of Character Transposition in the Left and Right Visual Fields.

This study examined the brain activity elicited by the hemispheric asymmetries and morpheme transposition of two-character Chinese words (canonical and transposed word) and pseudowords using event-related potentials (ERPs) with a dual-target rapid serial visual presentation (RSVP) task. Electrophysiological results showed facilitation effects for canonical words with centrally presented visual field (CVF) and right visual field (RVF) presentations but not with left visual field (LVF) presentations, as reflected by less negative N400 amplitudes. Moreover, more positive late positive component (LPC) amplitudes were observed for both canonical words and transposed words irrespective of the visual fields. More importantly, transposed words elicited a more negative N400 amplitude and a less positive LPC amplitude compared with the amplitudes elicited by canonical words for CVF and RVF presentations. For LVF presentations, transposed words elicited a less negative N250 amplitude compared with canonical words, and there was no significant difference between canonical words and transposed words in the N400 effect. Taken together, we concluded that character transposition facilitated the mapping of whole-word orthographic representation to semantic information in the LVF, as reflected by the N250 component, and such morpheme transposition influenced whole-word semantic processing in CVF and RVF presentations, as reflected by N400 and LPC components.

Hemifield-Specific Rotational Biases during the Observation of Ambiguous Human Silhouettes

Both static and dynamic ambiguous stimuli representing human bodies that perform unimanual or unipedal movements are usually interpreted as right-limbed rather than left-limbed, suggesting that human observers attend to the right side of others more than the left one. Moreover, such a bias is stronger when static human silhouettes are presented in the RVF (right visual field) than in the LVF (left visual field), which might represent a particular instance of embodiment. On the other hand, hemispheric-specific rotational biases, combined with the well-known bias to perceive forward-facing figures, could represent a confounding factor when accounting for such findings. Therefore, we investigated whether the lateralized presentation of an ambiguous rotating human body would affect its perceived handedness/footedness (implying a role of motor representations), its perceived spinning direction (implying a role of visual representations), or both. To this aim, we required participants to indicate the perceived spinning direction (which also unveils the perceived handedness/footedness) of ambiguous stimuli depicting humans with an arm or a leg outstretched. Results indicated that the lateralized presentation of the stimuli affected both their perceived limb laterality (a larger number of figures being interpreted as right-limbed in the RVF than in the LVF) and their perceived spinning direction (a larger number of figures being interpreted as spinning clockwise in the LVF than in the RVF). However, the hemifield of presentation showed a larger effect size on the perceived spinning direction than on the perceived limb laterality. Therefore, as we already proposed, the implicit representation of others’ handedness seems to be affected more by visual than by motor processes during the perception of ambiguous human silhouettes.

Hemispheric Asymmetry in Visual Processing: An ERP Study on Spatial Frequency Gratings

A hemispheric asymmetry for the processing of global versus local visual information is known. In this study, we investigated the existence of a hemispheric asymmetry for the visual processing of low versus high spatial frequency gratings. The event-related potentials were recorded in a group of healthy right-handed volunteers from 30 scalp sites. Six types of stimuli (1.5, 3 and 6 c/deg gratings) were randomly flashed 180 times in the left and right upper hemifields. The stimulus duration was 80 ms, and the interstimulus interval (ISI) ranged between 850 and 1000 ms. Participants paid attention and responded to targets based on their spatial frequency and location. The C1 and P1 visual responses, as well as a later selection negativity and a P300 component of event-related potentials (ERPs), were quantified and subjected to repeated-measure analyses of variance (ANOVAs). Overall, the performance was faster for the right visual field (RVF), thus suggesting a left hemispheric advantage for the attentional selection of local elements. Similarly, the analysis of the mean area amplitude of the C1 (60–110 ms) sensory response showed a stronger attentional effect (F+L+ vs. F−L+) at the left occipital areas, thus suggesting the sensory nature of this hemispheric asymmetry.

Testing the interhemispheric deficit theory of dyslexia using the visual half-field technique.

A deficit in interhemispheric transfer has been proposed as a neuropsychological theory of dyslexia. Interactions between the hemispheres during word recognition can be studied using the visual half-field paradigm. The well-established recognition advantage for right visual field (RVF) words over left visual field (LVF) words is thought to reflect the additional processing costs associated with callosal transfer of LVF word representations to the language-specialised left hemisphere. In addition, a further gain in recognition for bilateral presentation of a word has been attributed to cooperative interactions between the hemispheres. These recognition advantages can therefore be seen as behavioural indices of the efficiency of callosal transfer. This study aimed to replicate the finding of an absence of the bilateral advantage in developmental dyslexia, previously reported by Henderson et al. In all, 47 dyslexic and 43 control adult participants were tested, and no significant difference was found in the size of the bilateral advantage between the two groups. Our data did however replicate the previous finding of an increased RVF-LVF difference in dyslexic participants caused by poorer accuracy for LVF words (i.e., a greater LVF cost). This evidence is compatible with the interhemispheric deficit theory of dyslexia, suggesting an impairment in the transfer of visual word information from the right to the left hemisphere during reading.

Lateralization of attention in adults with ADHD: Evidence of pseudoneglect.

We investigated whether adults with attention-deficit/hyperactivity disorder (ADHD) show pseudoneglect-preferential allocation of attention to the left visual field (LVF) and a resulting slowing of mean reaction times (MRTs) in the right visual field (RVF), characteristic of neurotypical (NT) individuals -and whether lateralization of attention is modulated by presentation speed and incentives. Fast Task, a four-choice reaction-time task where stimuli were presented in LVF or RVF, was used to investigate differences in MRT and reaction time variability (RTV) in adults with ADHD (n = 43) and NT adults (n = 46) between a slow/no-incentive and fast/incentive condition. In the lateralization analyses, pseudoneglect was assessed based on MRT, which was calculated separately for the LVF and RVF for each condition and each study participant. Adults with ADHD had overall slower MRT and increased RTV relative to NT. MRT and RTV improved under the fast/incentive condition. Both groups showed RVF-slowing with no between-group or between-conditions differences in RVF-slowing. Adults with ADHD exhibited pseudoneglect, a NT pattern of lateralization of attention, which was not attenuated by presentation speed and incentives.

Visual Search for Letters in the Right Versus Left Visual Hemifields.

The current study investigated the relationships between attention, word processing, and visual field asymmetries. There is a discussion on whether each brain hemisphere possesses its own attentional resources and on how attention allocation depends on hemispheric lateralization of functions. We used stimuli with lateralized processing in an attentional task presented across the two visual hemifields. Three experiments investigated the visual search for a prespecified letter in displays containing words or nonwords, placed left and right to fixation, with a variable target letter position within the strings. In Experiment 1, two letter strings of the same type (words or nonwords) were presented to both visual hemifields. In Experiment 2, there was only one letter string presented right or left to fixation. In Experiment 3, two letter strings of different type were presented to both hemifields. Response times and accuracy data were collected. The results of Experiment 1 provide evidence for letter-by-letter search within a word in the left visual field (LVF), within a nonword in the right visual field (RVF), and for position-independent access to letters within a nonword in LVF and within a word in RVF. Experiment 3 produced similar results except for letter-by-letter search within words in RVF. In Experiment 2, for all types of letter strings in both hemifields, we observed the same letter-by-letter search. These results demonstrate that presence of stimuli in both one or two hemifields and the readiness to process a certain string type might contribute to the search for a letter within a letter string.

Music-reading expertise modulates the visual span for English letters but not Chinese characters.

Recent research has suggested that the visual span in stimulus identification can be enlarged through perceptual learning. Since both English and music reading involve left-to-right sequential symbol processing, music-reading experience may enhance symbol identification through perceptual learning particularly in the right visual field (RVF). In contrast, as Chinese can be read in all directions, and components of Chinese characters do not consistently form a left-right structure, this hypothesized RVF enhancement effect may be limited in Chinese character identification. To test these hypotheses, here we recruited musicians and nonmusicians who read Chinese as their first language (L1) and English as their second language (L2) to identify music notes, English letters, Chinese characters, and novel symbols (Tibetan letters) presented at different eccentricities and visual field locations on the screen while maintaining central fixation. We found that in English letter identification, significantly more musicians achieved above-chance performance in the center-RVF locations than nonmusicians. This effect was not observed in Chinese character or novel symbol identification. We also found that in music note identification, musicians outperformed nonmusicians in accuracy in the center-RVF condition, consistent with the RVF enhancement effect in the visual span observed in English-letter identification. These results suggest that the modulation of music-reading experience on the visual span for stimulus identification depends on the similarities in the perceptual processes involved.

Dynamics of electroencephalogram oscillations underlie right-eye preferences in predatory behavior of the music frog.

Visual lateralization is a typical characteristic of many vertebrates; however, its underlying dynamic neural mechanism is unclear. In this study, predatory responses and dynamic brain activities were evaluated in the Emei music frog (Nidirana daunchina) to assess the potential eye preferences and their underlying dynamic neural mechanism, using behavioral and electrophysiological experiments, respectively. To do this, when the prey stimulus (live cricket and leaf as control) was moved around the frogs in both clockwise and anticlockwise directions at constant velocity, the number of predatory responses were counted and electroencephalogram (EEG) absolute power spectra for each band were measured for the telencephalon, diencephalon and mesencephalon. The results showed that: (1) no significant differences in the number of predatory responses could be found for the control (leaf), but the number of predatory responses for the right visual field (RVF) was significantly greater than that for the left visual field (LVF) when the live cricket was moved into the RVF clockwise; (2) compared with no stimulus in the visual field and stimulus in the LVF, the power spectra of each EEG band were greater when the prey stimulus was moved into the RVF clockwise; and (3) the power spectra of the theta, alpha and beta bands in the left diencephalon were significantly greater than those of the right counterpart for the clockwise direction, but similar significant differences presented for the delta, theta and alpha bands in the anticlockwise direction. Together, the results suggested that right-eye preferences for predatory behaviors exist in music frogs, and that the dynamics of EEG oscillations might underlie this right eye/left hemisphere advantage.

Side Biases in Euro Banknotes Recognition: The Horizontal Mapping of Monetary Value.

Money is a special stimulus for humans, because of its relevance in everyday life. However, the basic mechanisms underlying money representation have not yet been fully investigated. Left-right asymmetries in the visual perception and evaluation of monetary value offer such a possibility. The pattern of these asymmetries can contribute to disentangle between numerical and emotional processes possibly involved in banknotes perception. In the present experiment, we tested the recognition of 5€and 100€ banknotes presented in the left and right visual fields. Results show that the 100€ banknote is recognized faster than the 5€ banknote in the Right Visual Field (RVF), while there is no difference in the Left Visual Field (LVF). Our interpretation is that this effect is due to the matching between the positive valence conveyed by the 100€ banknote and the side in which it is mapped (right-positive). We consider this result as evidence of a valence-based recognition of banknotes.

Language lateralisation measured across linguistic and national boundaries

The visual half-field technique has been shown to be a reliable and valid neuropsychological measurement of language lateralisation, typically showing higher accuracy and faster correct responses for linguistic stimuli presented in the right visual field (RVF) than left visual field (LVF). The RVF advantage corresponds to the well-known dominance of the left hemisphere (LH) in processing language(s). However, clinical and experimental neuroscientists around the globe use different variations of the visual half-field paradigm, making direct comparisons difficult. The current study used a word/non-word visual half-field paradigm with translingual stimuli. In total, 496 participants from seven European countries were investigated: Belgium (64), England (49), Germany (85), Italy (34), The Netherlands (87), Norway (51), and Switzerland (126), covering six international languages (Dutch, English, French, German, Italian, Norwegian). All language groups revealed a significant RVF/LH advantage in accuracy and reaction times that accounted for up to 26.1% of the total variance in performance. We found some variation in the degree of the RVF/LH advantage across language groups, accounting for a maximum of 3.7% of the total variance in performance. The RVF/LH advantage did not differ between subsamples speaking English, French or German as first or second languages or between monolingual and early/late bi/multilinguals. The findings suggest that the translingual lexical decision task (TLDT) is a simple but reliable measurement of language lateralisation that can be applied clinically and experimentally across linguistic and national boundaries.

Bi-lateralized Whorfian effect in color perception: Evidence from Chinese Sign Language

Abstract Converging behavioral and neural studies have shown a right visual field (RVF) advantage on language's effect on color categorical perception (the Whorfian effect). But little is known about the effect of sign language on deaf people's perception of color categories. To examine whether this lateralized effect also occurs in sign language systems, both behavioral and electrophysiological studies were conducted using visual search and oddball tasks respectively. The visual search results revealed that reaction times to targets were faster when the target and the paired distractor colors were easy to sign than when they were hard to sign, both in RVF and left visual field (LVF), and further, the LVF Whorfian effect was disrupted when participants performed the spatial interference secondary task. In the oddball task, the amplitude of the vMMN component evoked by the within-category deviant was significantly smaller than that evoked by the between-category deviant when displayed in either the RVF or the LVF. Both the behavioral and electrophysiological findings show that the language of the deaf affects their color perception bi-laterally, which suggests that the nature of language decides the pattern of the Whorfian effect.

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

Introduction A cortical region showing an event-related desynchronization (ERD) in the electroencephalographic (EEG) alpha power indicates that it is activated in preparation for voluntary movements. The aim of this study is to search for visual and spatial condition that degree and distribution of alpha band ERD by loading greater spatial attention with movement. Methods We measured movement-related ERD of scalp EEG over central to occipital areas. Just like Libet’s Clock paradigm, subjects were seated in front of a computer screen that displayed a clock rotating at 3 s per cycle. They were instructed to register in mind the onset time of the self-paced movement. After the movement, they reported the position of the clock when the movement took place. [Measurement 1] Two types of movement tasks were executed while the clock rotating direction is clockwise. In reaching trials, subjects reached the center of the screen with their right hand. In control trials, subjects performed a simple right wrist extension on the chair armrest. [Measurement 2] A wrist extension movement with right and left hand was performed in each of two kinds of rotating directions (clockwise and counterclockwise) of clock. Data analysis: We analyzed the effect of clock position, clock rotating direction, electrode position, side of hand, and type of movement to the EEG activity before the movement onset. The time-frequency representation of the EEG power was calculated using short-time Fourier transformation. Results [Measurement 1] In wrist extension, alpha band ERD was significantly greater in bilateral parieto-occipital area when clock position was in the left visual field (LVF) (while the clock is moving up) compared with the right visual field (RVF) (while the clock is moving down). Reaching trials showed the significant alpha band ERD in bilateral parieto-occipital area in both trials of LVF and RVF. [Measurement 2] There was a significant interaction between clock rotating direction and clock position that showed alpha band ERD in bilateral parieto-occipital area when the clock is moving up was significantly greater than that when the clock is moving down. This modulation is in common for the both left hand right hand movement. The common finding in measurement 1 and 2 is that alpha band ERD in the posterior area was greater in ipsilateral hemisphere to attended visual hemi-field compared with contralateral hemisphere. Conclusion We showed that alpha band power at motor preparation stage was significantly altered in posterior cortex by applying an appropriate spatial load in peripheral visual field without changing the movement itself.

Current Brain Research and the Composing Process: A Call For Interaction: Vol. 44, No. 2, January 1982

Current Brain Research and the Composing Process: A Call For InteractionVol. 44, No. 2, January 1982 Monica R. Weis I wish to God that some neurologist would sit down and figure out how the improviser's brain works, how he selects, out of hundreds of thousands of possibilities, the notes he does and at the speed he does—how, in God's name, his mind works so damned fast! and why, when the notes come out right, they are right…. Composing is a slow, arduous, obvious, inch-by-inch process, whereas improvisation is a lightning mystery. In fact, it's the creative mystery of our age.1 Alex Wilder's wish, quoted in a 1973 New Yorker, articulates for the field of jazz the basic question facing serious teachers of composition. What really happens in the composing process? Why does a flash of intuition often make the crucial difference between a merely artificial piece of writing and a sincere authentic voice? Not only why does it make a difference, but precisely how does it make a difference? In focusing on this question, I would like to summarize in this paper more briefly than good scholarship recommends, current areas of brain research that provide information about hemispheric asymmetry—information that should influence the direction of English education. It has long been suspected that the two cortical hemispheres of the brain are concerned with different operations or modes of knowing, i.e., the left hemisphere, which controls the production of speech, perceives the world logically, critically, and sequentially; whereas the right hemisphere is involved in intuitive, holistic patterning, visual, spatial, musical apprehension. Because thinking is such a complex operation of largely unmeasurable interacting elements, no precise and conclusive data really isolates and explains what happens. However, by examining patients who, for medical reasons, have only one operative hemisphere, neurosurgeons and scientists are discovering some surprising information about brain activity. Let me briefly cite a few examples. A.R. Luria, the Russian psychologist, worked with a musician who, after his stroke, composed better music than before his illness. Although he could no longer speak or write down the notes, he could play them and remember them. It would seem that some dimension of his musical ability was developed or released after his speech faculties were impaired. In effect, he was communicating in a [End Page 225] new way through music.2 Similarly, it is not unusual for a speech or physical therapist to succeed in getting some aphasic stroke victims to write, indicating that perhaps cerebral integration can overcome or bypass the injured site.3 Recently, at NY University of Rehabilitation, Andrea Glass taught an 84-year-old woman who could neither speak nor understand speech to communicate via shaped and colored plastic symbols.4 Experiments with split-brain individuals (epileptics who have undergone commissurotomy, which severs the corpus callosum between the cortical hemispheres to reduce the occurrence of seizures), support this data and provide the additional advantage of presenting problem-solving tasks to two separate and functioning brains. By using special contact lenses, information presented to the left visual field (LVF) is processed only in the right hemisphere (RH) and information presented to the right visual field (RVF) is processed only in the left hemisphere (LH). Milner and Taylor (1972) found that the right hemisphere demonstrated superior visuospatial performance. When a design was presented to the right hemisphere, the left hand drew more accurate pictures than when the design was presented to the left hemisphere for the right hand response.5 This is not just a case of better muscle coordination, as has been demonstrated in another experiment by Michael Gazzaniga. His split-brain patient was asked to duplicate an arrangement of blocks and then to duplicate a 3-D drawing of a cube. The right hand (responding to information processed by the left hemisphere) was unable to perform either task, that is, the left hemisphere could not process the visual and spatial information being presented to it.6 In addition to visuo-spatial perception, the right hemisphere seems capable of generating emotional reactions. Sperry and Gazzaniga flashed a picture of a nude to the LVF-RH of a split-brain...

Face inversion reveals holistic processing of peripheral faces

Face perception is accomplished by face-selective neural processes, involving holistic processing that enables highly efficient integration of facial features into a whole-face representation. It has been shown that in face-selective regions of the ventral temporal cortex (VTC), neural resources involved in holistic processing are primarily dedicated to the central portion of the visual field. These findings raise the intriguing possibility that holistic processing might be the privilege of centrally presented faces and could be strongly diminished in the case of peripheral faces. We addressed this question using the face inversion effect (FIE), a well-established marker of holistic face processing. The behavioral results revealed impaired identity discrimination performance for inverted peripheral faces scaled according to the V1 magnification factor, compared to upright presented faces. The size of peripheral FIE was comparable to that found for centrally displayed faces. Face inversion affected the early ERP responses to faces in two time intervals. The earliest FIE was most pronounced in the time window between 130 and 140 msec following stimulus presentation, for both centrally and peripherally displayed faces and in the latter case, it was present only over the contralateral hemisphere. The timing of the next component FIE corresponded closely with the temporal interval of the N170 ERP component and showed strong right hemisphere (RH) lateralization, both when faces were displayed in the left or right visual field (RVF). Furthermore, we also showed that centrally presented face masks impaired peripheral face identity discrimination performance, but did not reduce the magnitude of the FIE. These findings revealed robust behavioral and neural inversion effects for peripheral faces and thus suggest that faces are processed holistically throughout the visual field.